Vascular Hemodynamics

14:00         2825.     Flow Sensitive MRI in a Realistic Model System of the Thoracic Aorta with Aortic Coarctation

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Ramona Lorenz¹, Aurélien F. Stalder¹, Jelena Bock¹, Dominic Klausmann², Christoph Benk¹, Jürgen Hennig¹, Michael Markl¹

¹University Hospital Freiburg, Freiburg, Germany; ²University Freiburg, Freiburg, Germany

The purpose of this study was to establish a realistic model system for the evaluation of hemodynamics consequences of aortic coarctation with different stenosis grades. Flow sensitive 4D MRI was performed within a realistic rapid prototyping vascular model of the thoracic aorta with attached flexible stenosis in the descending aorta which was integrated into a pulsatile flow circuit. A novel approach for generating realistic pulsatile waveforms was realized by a pneumatically driven VAD (ventricular assistant device) pump system. The study presents an evaluation of the impact of stenosis grade on local and global flow dynamics.

14:30         2826.     Flow Sensitive 4D MRI: Descending Aortic Retrograde Flow and Embolization Risk in Acute Stroke Patients

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Michael Markl¹, Christoph Strecker², Patrick Dudler², Andrea Nußbaumer², Jelena Bock¹, Aurelien F. Stalder¹, Alex Frydrychowicz¹, Anna L. Stroh³, Cornelius Weiller², Jürgen Hennig¹, Andreas Harloff²

¹Dept. of Diagnostic Radiology, Medical Physics, University Hospital, Freiburg, Germany; ²Dept. of Neurology, University Hospital, Freiburg, Germany; ³Dept. of Cardiology, University Hospital, Freiburg, Germany

Flow-sensitive 4D MRI allows the detailed visualization of both physiological and pathological 3D aortic blood flow characteristics and was used to determine the role of retrograde flow in the descending aorta (DAo) in patients with acute embolic stroke. Our findings demonstrate a high incidence of retrograde flow in the proximal DAo suggesting that complex DAo plaques should be considered as a novel high-risk embolic source in patients with undetermined stroke etiology.

15:00         2827.     Analysis of 3D Flow Dynamics in a Ventricular Assist Device by Flow Sensitive 4D MRI

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Michael Markl¹, Ramona Lorenz¹, Jelena Bock¹, Christoph Benk², Dominic Klausmann², Alex Frydrychowicz¹, Jürgen Hennig¹, Friedhelm Beyersdorf²

¹Dept. of Diagnostic Radiology, Medical Physics, University Hospital, Freiburg, Germany; ²Dept. of Cardiovascular Surgery, University Hospital, Freiburg, Germany

The assessment of flow characteristics inside ventricular assist devices (VADs) using MRI techniques may provide insight into the mechanisms underlying the high rate of thrombo-embolic events after VAD implantation. These investigations may form the basis to optimize the device’s design and its need for anticoagulation. The purpose of this study was to integrate a clinical routine VAD into a flow circuit with realistic geometric and pulsatile inflow conditions. Flow sensitive Magnetic Resonance Imaging (MRI) at 3 Tesla permitted the detailed analysis of local and global 3D flow dynamics in a realistic environment.

15:30         2828.     Diameter-Dependence of Aortic Hemodynamics: Does Size Matter?

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Alex Frydrychowicz¹, Alexander Berger¹, Aurélien F. Stalder¹, Maximilian F. Russe¹, Andreas Harloff¹, Mathias Langer¹, Jürgen Hennig¹, Michael Markl¹

¹University Hospital Freiburg, Freiburg, Germany

It was the aim of this study based on flow-sensitive 4D MRI to analyze the diameter dependence of aortic hemodynamics with respect to characteristic blood flow patterns such as time to maximum arterial flow, duration of backward flow, number of vortices, and the presence of helical flow, which can be correlated to wall shear stress (WSS) and oscillatory shear index (OSI). The results of this study indicate the method¡¯s potential to identify characteristic, diameter dependent, aortic flow patterns. In a cohort of 62 individuals which were subgrouped by the diameter of the ascending aorta (SAD-group ¡Ü 3.5cm < LAD-group) we showed that the size of the aorta influences the hemodynamic properties.

14:00         2829.     Multi-Dimensional Velocity Field Reconstruction from Sparsely Sampled 3D Phase Contrast MRI

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Kartik Sivaram Sundareswaran¹, Dave Harold Frakes¹, Mark Fogel², Oskar Skrinjar¹, Ajit P. Yoganathan¹

¹Georgia Institute of Technology, Atlanta, Georgia, USA; ²Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA

A new technique for velocity field reconstruction is presented in this paper that utilizes blood flow incompressibility as a property for estimating continuous flow field representation in blood vessels using a stack of contiguous phase contrast MRI. The methodology has been tested on 15 in vivo datasets of patients with a single ventricle circulation, and the results indicate superior qualitative and quantitative velocity reconstruction compared to other traditional techniques for flow reconstruction from PC MRI. This opens up new avenues for higher order analysis (vortex structures, energy loss) of PC MRI flow fields.

14:30         2830.     In Vivo MR Determination of Flow Fields in Patients with Intracranial Aneurysms Using 7D PC-MRI

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Gabriel Acevedo-Bolton¹, Alastair Martin¹, Vitaliy Rayz¹, Loic Boussel¹, David Saloner¹,²

¹UCSF, San Francisco, California , USA; ²VAMC San Francisco, San Francisco, California , USA

7D PC-MRI was used to measure and map the blood flow within intracranial aneurysms in vivo. These flow results were compared  with in vitro reproductions and with the predictions of computational fluid dynamics(CFD) models. It was found to be essential to determine all three components of the velocity to adequately visualize the complex flow structures

15:00         2831.     Patient-Specific Hemodynamics of the Descending Aorta: Combination of CFD and 4D Flow-Sensitive MRI

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Aurélien F. Stalder¹, Zhenyu Liu², Michael Markl¹, Jürgen Hennig¹, Jan Korvink²

¹University Hospital Freiburg, Freiburg, Germany; ²University of Freiburg, Freiburg, Germany

Flow-sensitive 4D MRI allows in vivo 3D blood flow visualization and flow parameter estimation but is limited by spatio-temporal resolution and measurement errors. In contrast, Computational Fluid Dynamics (CFD) can compute very accurate flow fields from modeled arteries but depends on the validity of the hemodynamic model and boundary conditions. We show for the first time an integration of 4D flow-sensitive MRI and CFD into a single framework. A combination of those 2 complementary approaches offers reciprocal validation possibilities and has the potential to refine flow measurements which may result in more accurate quantification of complex in vivo hemodynamic phenomena.

15:30         2832.     4D Flow of the Whole Heart and Great Vessels at 3T Using Real Time Self Respiratory Gating

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Sergio Andres Uribe¹, Philipp Beerbaum¹, Allan Rasmusson², Thomas Sangild Sørensen², Reza Razavi¹, Tobias Schaeffter¹

¹Kings College London, London, UK; ²University of Aarhus, Aarhus, Denmark

We present an extension of a self-respiratory technique to acquire 4D flow data. Self-navigation is obtained from k-space center profiles and the breathing signal is used in real time to gate the scan. The method allows us to acquire an isotropic non-angulated volume, 4D flow encoded, of the whole heart and great vessel in a single free-breathing scan. Results showed a strong correspondence between flow patterns obtained using this technique and with 2D flow. This approach represents an important advance for the characterization of the flow hemodynamics in the whole heart and a step forward to simplify cardiac MR examinations.

Vessel Compliance

14:00         2833.     A New Methodology for Determining Aortic Pulse Wave Velocity Using 2D PCMR Velocity Data

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Samuel Fielden¹,², Brandon Fornwalt², Michael Jerosch-Herold³, Robert Eisner¹, Arthur Stillman¹, John Oshinski¹,²

¹Emory University, Atlanta, USA; ²Georgia Institute of Technology/Emory University, Atlanta, USA; ³Oregon Health & Science University, Portland, USA

A novel method for estimating aortic pulse wave velocity is presented.  This method uses 2D PCMR data to construct blood velocity magnitude images in order to determine multiple flow waveforms in the ascending, transverse, and descending sections of aorta.  The waveform at each location is compared to the most proximal waveform via cross correlation to determine the time delay of the wave at that location and thus the pulse wave velocity.  This method is more reproducible than either of two more established methods examined.

14:30         2834.     Measurement of Aortic Pulse Wave Velocity in Volunteers

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Neva Hiten Patel¹, Mark Butlin², Richard T. Black¹, Martin J. Graves,¹³, Stacey Hickson⁴, Carmel McEniery⁴, Ian B. Wilkinson⁴, David J. Lomas³

¹Addenbrooke's Hospital NHS Trust, Cambridge, UK; ²Macquarie University, Sydney, Australia; ³University of Cambridge, UK; ⁴University of Cambridge, Cambridge, UK

Aortic pulse wave velocity (PWV) can be used as an index of the increased risk of cardiovascular disease which is associated with aortic wall stiffness. A number of groups have looked at measuring PWV using MRI, however we are not aware of any reported studies addressing the best method of obtaining the transit-time used to calculate the PWV, and the reproducibility of PWV measurement. We have performed repeated MRI PWV measurements in healthy volunteers and investigated several different methods of transit-time calculations.

15:00         2835.     The Effect of Wall Compliance on Aortic Hemodynamics in the Mouse: Implications for AAA Pathogenesis

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Smbat Amirbekian¹, Robert C. Long¹, Jin Suo², W Robert Taylor¹,², Don P. Giddens², John N. Oshinski¹,²

¹Emory University, Atlanta, Georgia, USA; ²Georgia Tech, Atlanta, Georgia, USA

MRA and PC-MRI were used to provide geometric and flow boundary conditions for a computational study of the hemodynamics of the mouse aorta.  The study showed that incorporating vessel compliance changes the flow patterns seen in the aorta and that a rigid vessel creates areas of oscillatory wall shear stress.

15:30         2836.     Measurement of Common Carotid Artery Lumen Dynamics During Cardiac Cycle Using TrueFISP Cine MR Imaging

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Tracy Yee Mau Chow¹,², Jerry S. Cheung¹, Yin Wu¹, Ed X. Wu¹

¹The University of Hong Kong, Pokfulam, Hong Kong

Vascular MR imaging provides detailed anatomical information of blood vessels, yielding lumen size and wall thickness measurements. However, many of the studies often specify the morphology and composition of vessel walls without examining the dynamic pulsatile properties of these vessels. In this study, the vascular dynamics of the right and left common carotid arteries throughout the whole cardiac cycle was investigated using TrueFISP cine cardiac imaging. Consistent results and area waveform patterns were observed among the normal subjects. This lumen dynamics can better describe physiological behaviour correlated with other vascular parameters, therefore has potential clinical importance in differentiating abnormalities. Furthermore, TrueFISP cine MRI produces high contrast images, allowing high accuracy in area measurements and thus waveform tracing.

Myocardial T2 & T2* Imaging

14:00         2837.     Spiral T2 Quality Evaluation in Patients with Coronary Artery Disease

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Warren Foltz¹, Kim Alexander Connelly¹, Ram Vijayaraghavan¹, Venkat Ramanan, Gideon Paul¹, Graham Wright¹, Alexander Dick¹

¹Sunnybrook Health Sciences Centre, Toronto, Canada

T2 has proven to be a valuable contrast mechanism for myocardial characterization because it is a quantitative biomarker of acute and sub-acute inflammatory processes. Clinical integration of T2 relies on T2-weighted black-blood  fast-spin echo (FSE) imaging because cardiac-gated imaging is achievable in breath-hold scan times and with useful spatial resolutions.  However the information is semi-qualitative and the echo-train readout compromises T2 contrast. A magnetization-prepared spiral imaging method, termed T2prep, should improve reproducibility in clinical quantification of myocardial T2 relaxation because variability associated with coil shading is removed.  In the absence of gross relaxation fluctuations, current clinical myocardial FSE scanning is useful only to delineate cardiac margins. Quantitative T2prep mapping reduces variability towards physiological noise levels, providing more reproducible measurements with the potential for faster scan times at minor cost to spatial resolution and ROImin.

14:30         2838.     Using T2*-Maps as a Quantitative Indicator for Myocarditis

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Karl-Heinz Herrmann¹, Diane Renz¹, Pascal Baltzer¹, Ines Krumbein¹, Jürgen R. Reichenbach¹

¹Friedrich-Schiller-University, Jena, Germany

Diagnosis of myocarditis with standard sequences like late enhancement, T2 TSE or T2-weighted TIRM is not always conclusive because any through plane motion of the myocardium causes inhomogeneous signal due to the repeated slice selective inversion and excitation pulses. A quantitative T2*-map may be helpful in quantifying, delineating and detecting edema associated with myocarditis.

15:00         2839.     Retrospective Correction for Induced Magnetic Field Inhomogeneity in Measurements of   Large-Vessel Hemoglobin Oxygen Saturation by MR Susceptometry

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Michael Langham¹, Tom Floyd², Jeremy Magland¹, Felix W. Wehrli¹

¹University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA; ²Univesity of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA

The main source of error in MR susceptometry is the static field inhomogeneity that is characterized by low spatial-frequency modulation on the phase image. High-pass filtering has previously been used in conjunction with shimming. We propose an alternative method which acquires data without scanner-implemented default shimming, and fit, after appropriate weighting and masking, the static field inhomogeneity to a second-order polynomial. Compared to shimming, the retrospective correction technique improved agreement between hemoglobin saturations measured in different segments of a vessel (femoral versus popliteal artery and vein) from three standard errors to less than one.

15:30         2840.     Multislice Multiecho T2* Cardiovascular Magnetic Resonance Can Detect Heterogeneous Myocardial Iron Distribution in Thalassemia Patients

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Vincenzo Positano¹, Alessia Pepe¹, Anna Ramazzotti¹, Daniele De Marchi¹, Brunella Favilli¹, Eliana Cracolici², Maria Gabriella Brizi³, Maria Filomena Santarelli¹, Massimo Lombardi¹, Luigi Landini⁴

¹Institute of Clinical Physiology, Pisa, Italy; ²University of Palermo, Palermo, Italy; ³A. Gemelli University Hospital, Roma, Italy; ⁴University of Pisa, Pisa, Italy

In this study we investigate the relationship between segmental R2* heterogeneity assessed by multi-slice multi-echo MRI and iron overload progression in a large thalassemia major patient population. Real data were compared with a surrogate data sets obtained stating that the inhomogeneous segmental distribution of R2* would be generated by susceptibility artefacts. Inhomogeneities in R2* myocardial distribution in iron overloaded subjects cannot be explained by the effect of susceptibility artefacts, that are additive in the R2* domain and should vanish at high iron overload levels. A possible interpretation is that a true heterogeneity in iron overload distribution in TM patients exists.

Vessel Wall Imaging

14:00         2841.     An Optimized 3D Inversion Recovery Prepared Fast Spoiled Gradient Recalled Sequence with Multiple Echoes (IR FSPGR ME) for Carotid Plaque Imaging

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David C. Zhu¹, J Kevin DeMarco¹, Anthony T. Vu²

¹Michigan State University, East Lansing, Michigan, USA; ²GE Healthcare, Waukesha, Wisconsin, USA

An optimized 3D inversion recovery prepared fast spoiled gradient recalled sequence with multiple echoes (IR FSPGR ME) on a 3T scanner for carotid plaque imaging is presented.  It maintains the ability of its single-echo counterpart in blood and fat signal suppression at the carotid region as well as the benefits of high-resolution volumetric visualization and hemorrhage detection. The IR FSPGR ME sequence can potentially further characterizes hemorrhage types through the generated T₈* maps. In addition, combining images from the individual echoes provides a higher signal-to-noise ratio and thus improve image visualization.

14:30         2842.     Optimization of Motion Sensitized Driven Equilibrium (MSDE) Preparation Scheme for Multi Contrast 3D Vessel Wall Imaging at 3.0T

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Makoto Obara¹,², Masatoshi Honda³, Rie Nozaki², Marc Van Cauteren¹, Kagayaki Kuroda²

¹Philips Medical Systems, Minato-ku, Japan; ²Tokai University, Hiratsuka-shi, Japan; ³Tokai University Hospital, Isehara-shi, Japan

3D turbo field echo (TFE) sequence prepared by motion sensitized driven equilibrium (3D-MSDE-TFE) was optimized for T1W and T2W carotid artery wall imaging and compared to the conventional 2D double inversion recovery (DIR) turbo spin echo (TSE). T1 and T2 contrasts of 3D-MSDE-TFE were controlled by adjusting the MSDE preparation time, shot interval and acquisition flip angle. MSDE optimization was achieved by changing the number of refocusing pulses from 1 to 4 using MLEV scheme. Achieved T1 and T2 contrasts of the optimized 3D-MSDE-TFE were similar to those of conventional 2D-DIR while scan time was 2 times faster. Therefore, this approach may be appropriate for vessel wall screening.

15:00         2843.     Evaluation of the Relationship Between the Superficial Calcification and Intraplaque Hemorrhage in the Atherosclerotic Carotid Plaque by 3T High Resolution MRI

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Haiyue Ju¹, Xian Xu¹, Lin Ma¹, Zulong Cai¹, Youquan Cai¹, Xinjiang Wang¹, Jianming Cai¹

¹Chinese PLA General Hospital, Beijing, People's Republic of China

We aim to evaluate the relationship between the shape and location of superficial calcification and intraplaque hemorrhage in the atherosclerotic carotid plaque. One hundred and eighty three slices with superficial calcification in 51 patients were enrolled in this study. All the patients underwent 3T MRI examination with a contrast-enhanced multi-contrast weighted protocol. This study showed that the nodular type of superficial calcification in the atherosclerotic carotid plague has higher possibility of simultaneous occurrence with intraplaque hemorrhage than that of patchy type, whereas, in hemorrhage group, the percentage of either marginal or central type of superficial calcification is not significantly different from that in non-hemorrhage group.

15:30         2844.     Gadolinium Contrast Enhancement of Carotid Atherosclerotic Plaque is Associated with Symptomatic Status

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Jianming Cai¹, Niranjan Balu², Dongxiang Xu², Haiyue Ju¹, Xian Xu¹, Xihai Zhao¹, Chun Yuan²

¹Chinese PLA General Hospital, Beijing, People's Republic of China; ²University of Washington, Seattle, USA

Symptomatic carotid atherosclerosis is known to be associated with plaque neovasculature and inflammation. An increase in vasa vasorum accompanies the increased inflammation and plaque neovasculature of advanced atheorsclerosis. The increased blood supply from the vasa vasorum plexus surrounding the carotid artery may be reflected in contrast enhancement (CE) patterns of the outerwall. The association between outerwall CE on black-blood contrast-enhanced MRI (CE-MRI) and symptomatic status was investigated in 24 patients. Outerwall CE was clearly visualized by CE-MRI. Symptomatic status was found to be associated with a more homogenous outerwall CE compared to asymptomatic arteries.

14:00         2845.     DSCT and 3T MR for Characterization of Carotid Plaque in Patients

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John J. Sheehan¹, Natasha Berg², Timothy Carroll², Peter J. Weale³, Renate Jerecic³, James C. Carr²

¹Northwestern University, Chicago, Ireland; ²Northwestern University, Chicago, Illinois, USA; ³Siemens Medical Solutions, Chicago, Illinois, USA

Atherosclerotic disease is a significant cause of morbidity and mortality.  Recent studies have suggested that plaque composition is an important prognostic factor and may be more predictive of adverse outcomes than overall degree of stenosis.  Previous studies have attempted to characterize carotid plaque components using various imaging modalities.  In this small patient study, we looked at the relative efficacy of two new technologies, 3 Tesla (3T) MR and Dual Source CT (DSCT) to evaluate plaque components.  We hypothesized that these modalities could provide improved depiction of plaque components, which may have important diagnostic and therapeutic implications.

14:30         2846.     Single-Shot DENSE MRI of the Carotid Arteries

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Alexander Peter Lin¹,², Eric Bennett², Yuan Le², Scott Fraser¹, Han Wen²

¹California Institute of Technology, Pasadena, California , USA; ²National Institutes of Health, Bethesda, Maryland, USA

DENSE strain mapping of the carotid artery wall systolic distension provides regional stiffness measures. However, the scan lasts several minutes, and segmented k-space acquisition suffers from artifacts due to head-neck motion and turbulent in-plane blood flow. This problem is solved with a single-shot imaging sequence and rigid body image registration in postprocessing.

15:00         2847.     MRI-Based Biomechanical Imaging: Role of Hemodynamic Forces on the Early Plaque Remodeling

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Jie Zheng¹, Dana Abendschein¹, Ruth J. Okamoto², Deshan Yang¹, Kyle McCommis¹, Bernd Misselwitz³, Robert J. Gropler¹, Dalin Tang⁴

¹Washington University School of Medicine, Saint Louis, USA; ²Washinton University, Saint Louis, USA; ³Bayler Schering Pharma AG, Berlin, Germany; ⁴Worcester Polytechnic Institute, Worcester, Massachusetts, USA

Local hemodynamic forces play important roles in the regulation of early atherosclerosis progression and vessel remodeling. A MRI-based biomechanical imaging technique was developed and evaluated in vivo in a porcine atherosclerotic plaque model. A plaque targeted contrast-enhanced MR images provided plaque structure for the computational modeling in this technique. Progression and regression of the early plaques were observed and flow shear stress show consistent findings with other reports. Furthermore, structures stress and strain also demonstrated strong correlations with plaque progression and regression, indicating multi-factors of hemodynamic effect to the early atherogenesis.

15:30         2848.     Characterization of Ex Vivo Carotid Plaque with 3T MRI: A Comparison with Histology

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Natasha Berg¹, John Joseph Sheehan¹, Peter J. Weale², Mark Morasch¹, Nicole Mascheri¹, James C. Carr¹, Timothy Carroll¹

¹Northwestern University, Chicago, Illinois, USA; ²Siemens Medical Solutions, Chicago, Illinois, USA

Atherosclerotic disease of the carotid artery is a significant cause of morbidity and mortality.  Previous imaging techniques have focused on quantifying stenosis in the vessel, but recent research suggests that composition of plaque may be a more important prognostic factor.  Ex vivo studies of carotid plaques have attempted to characterize plaque using 1.5 T MR and have shown that 2D PDW, T1W and T2W sequences on MRI may have some utility in demonstrating areas of fibrous matrix and necrotic core. Here, we perform an intial evaluation of 3T MRI in the characterization of ex-vivo carotid plaque specimens.

14:00         2849.     High-Resolution Multi-Contrast MRI Characterization of Rabbit Atherosclerosis Using Clinical Pulse Sequences

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Andre Jean-Louis Belisle¹,², John A. Ronald,¹², Kem A. Rogers¹, Brian K. Rutt,¹²

¹University of Western Ontario, London, Canada; ²Robarts Research Institute, London, Canada

We used multi-contrast ex vivo 3T MRI of aortic specimens from defined regions of a low-level long-term cholesterol-fed rabbit model of atherosclerosis. The objective was to collect high-resolution images using clinically available pulse sequences to resolve the structural components of plaques and to provide histological verification. The most complex regions of plaque appear to be in the descending aortic arch which was demonstrated by all sequences and is especially evident when compared to T2w controls. Eventually this research could be used for visualizing the vulnerable plaque and direct further in vivo research by specifying imaging target regions in the aorta.

14:30         2850.     In Vivo & Ex Vivo Micro-MRI in Detection of Mouse Atherosclerotic Plaques: An MRI-Histopathology Correlation Study

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Daohai Xie¹,², Bensheng Qiu¹, Jiangyang Zhang³, Xiaoming Yang¹

¹University of Washington, Seattle, Washington, USA; ²Suzhou University School of Medicine, Suzhou, People's Republic of China; ³Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

Atherosclerotic cardiovascular disease remains the leading cause of death in the developed countries. Continuous efforts are warranted to understand more about the pathogenesis and management of atherosclerotic cardiovascular disease. High-field micro-MR technology offers both high spatial resolution and whole-body coverage. This study focused on evaluation of capability using in vivo and ex vivo micro-MRI to detect mouse atherosclerotic plaques, which was correlated with histopathology.  The results of the current study may encourage the continued efforts to develop high-field MR imaging techniques to characterize atherosclerotic plaques in vivo, so-called ¡°in-vivo plaque pathology,¡± which should become an essential imaging tool for early diagnosis and efficient treatment of atherosclerotic cardiovascular disease.

15:00         2851.     in vivo MRI and MRA Assessment of Patency in a Novel Model of Vascular Remodelling Using Patent Aortic Grafts

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King Kenneth Cheung¹,², Andrew R. Thompson³, H Hafez⁴, Andrew M. Taylor², Roger J. Ordidge¹, Stephen E. Humphries³, Mark F. Lythgoe²

¹University College London (UCL), London, UK; ²UCL, London, UK; ³Royal Free & University College London Medical School, London, UK; ⁴St Richards Hospital, Chichester, UK

Fibulin-5 (fbln-5) is an extracellular matrix protein that is central to elastic fibre maturation and vessel development. A novel model has been devised to investigate the role of fbln-5 in vascular remodelling in a patent vessel. As sustained graft patency is central to this model, we evaluated the accuracy of MRI and MRA for determining graft patency in vivo. MRI and MRA correctly identified all patent (n=8) and non-patent (n=3) grafts. The non-invasive and robust nature of MRI and MRA offers an excellent alternative to traditional assessment through repeated invasive surgery, thus improving survival and reducing animal usage.

15:30         2852.     Characterisation of Vascular Injury Responses Following Balloon Injury of the Rat Carotid Artery Using Combined in vivo Imaging and ex Vivo Microscopy

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King Kenneth Cheung*¹,², Manfred Junemann-Ramirez*², Pauliina Lehtolainen², Alan Rudiger², Mark Turmaine, David Sanz², Roger J. Ordidge¹, John F. Martin², Mark F. Lythgoe²

¹University College London (UCL), London, UK; ²UCL, London, UK

The vascular endothelium is crucial in regulating biological functions such as haemostasis. However this layer is often impaired in cardiovascular diseases. Understanding the evolution of vascular remodelling is therefore of great importance and may provide insights for the development of novel interventions. Here we present the use of in vivo MRI and vascular ultrasound in combination with ex vivo electron microscopy for extensive characterisation of the events involved in vascular remodelling following balloon angioplasty of the rat carotid artery over a 28 day follow-up period.

14:00         2853.     New Insights Into Ruptured Plaques: Enhanced Detection of Neovasculature and Fibrous Tissue by MRI

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Alkystis Phinikaridou¹, Kevin J. Hallock¹, Ye Qiao¹, James A. Hamilton¹

¹Boston University, Boston, Massachusetts, USA

We used the Constantinides New Zealand White rabbit model to study atherosclerosis and controlled plaque rupture associated with thrombosis. We combined contrast enhanced (Gd-DTPA) in vivo (3T) and magnetization transfer (MT) ex vivo (11.7T) MRI coupled to histology to identify features associated with vulnerable plaques. In vivo, Gd-DTPA uptake was associated with plaque regions rich in neovasculature as well as fibrous tissue. Ex vivo MT identified the location of fibrous cap rupture and fibrosis seen within organized thrombi. Further studies about the kinetics of Gd-DTPA within plaques together with the in vivo application of MT will provide insights about plaque vulnerability.

14:30         2854.     Enhancement of the Atherosclerotic Plaque and the Vessel Wall of the Carotid Artery After Injection of a Blood-Pool Contrast Agent
[Not Available]

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Sietske Rozie¹, Piotr A. Wielopolski¹, Mohamed Ouhlous¹, Wiro Niessen, Theo van Walsum, Aad van der Lugt¹

¹Erasmus Medical Center, Rotterdam, Netherlands

Purpose: We hypothesized that a blood-pool agent enhances the outer wall of the carotid artery and specific parts of the atherosclerotic carotid plaque

Methods: We studied 26 atherosclerotic plaques of 15 consecutive patients with severe carotid stenosis. On a 3.0T scanner a 3DT1-weighted scan was performed before injection and 20 minutes after injection.

Results: The mean enhancement on the 20 minute delay scan was 40.9% ± 32.5% in the non-calcified part of the plaque and 60.0% ± 21.7% in the vessel wall of the symptomatic carotid arteries.

Conclusions: Images obtained before and after contrast injection with Vasovist® may improve atherosclerotic plaque characterisation and quantification.

15:00         2855.     In Vivo and ex Vivo plaque Characterisation in the Aortic Arch of ApoE -/- Mice with High-Resolution Multi-Parametric Magnetic Resonance Imaging at 17.6 Tesla

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Gert Klug¹, Volker Herold¹, Marco Parczyk¹, Elisabeth Bauer¹, Thomas Schulze-Till¹, Eberhard Rommel¹, Peter Jakob¹, Wolfgang Bauer¹

¹University of Wuerzburg, Wuerzburg, Germany

High-Resolution plaque imaging in atherosclerotic apoE knock-out (-/-) mice has been recently shown to correlate closely with histology. However these results are limited to the aortic-root. We intended to further enhance the ability of high-field magnetic resonance (MR) to characterize plaque formation in murine models of atherosclerosis at microscopic levels. Our results demonstrate that high resolution multi-parametric plaque imaging at 17.6 Tesla is feasible with good correlation to HE histology but further studies are necessary to distinguish plaque components compared to a more comprehensive histology protocol.

15:30         2856.     Molecular Imaging of Atherosclerosis Using Paramagnetic Cy5.5-Labeled PEG-Micelles

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Sjoerd Hak¹, Geralda A.F. van Tilborg¹, Esad Vucice², Gustav J. Strijkers¹, Klaas Nicolay¹, Zahi A. Fayad², Willem Jan Menno Mulder²

¹Eindhoven University of Technology, Eindhoven, Netherlands; ²Mount Sinai School of Medicine, New York, New York, USA

In this study a new contrast agent for molecular imaging of atherosclerosis was used, paramagnetic Cy5.5-labeled PEG-micelles. The targeting ligand used was the RGD-peptide. In vivo MRI and ex vivo fluorescence techniques demonstrated active uptake of RGD-PEG-micelles into atherosclerotic plaque in apoE-knockout mice. The near infrared Cy5.5 fluorophore proofed to be very valuable for ex vivo fluorescence imaging as there is less autofluorescence and better penetration at higher wavelengths. The non-specific uptake of bare PEG-micelles in mouse plaques was very limited. This makes this contrast agent very attractive for molecular imaging of atherosclerosis, also when directed to other targets.

Cardiac Image Processing

13:30         2857.     Real-Time Cardiovascular Imaging Using a Combination of HYPR, McKinnon-Bates, and COM Gating Algorithms

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Lauren A. Keith¹, Dana C. Peters, Julia V. Velikina¹

¹University of Wisconsin - Madison, Madison, Wisconsin, USA

We use a combination of the HYPR and McKinnon-Bates algorithms along with center of mass self-gating in order to improve spatial resolution, signal-to-noise ratio and reduce artifact levels in real-time cardiovascular imaging.

14:00         2858.     Characteristics and Performance of the Karhunen-Loeve Transform Filter in Dynamic Cardiac Magnetic Resonance Imaging

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Yu Ding¹, Yiu-Cho Chung², Subha V. Raman³, Orlando P. Simonetti³

¹The Ohio State University, Columbus, Ohio, USA; ²Siemens Medical Solutions, Inc., Columbus, Ohio, USA; ³The Ohio State University, Columbus, Ohio, USA

We describe the characteristics and performance of a new temporal filter based on the optimal linear transform, the Karhunen-Loeve Transform. The filter is designed to suppress noise in dynamic cardiac MR images without compromising the sharpness of stationary or moving edges or other structures. We derive a simple mathematical formula for the noise reduction effect of this filter, and then verify it in real-time cardiac cine MRI with TSENSE acceleration factor 4 in normal volunteers.  A SNR gain of 144% was achieved after filtering without edge blurring or other artifacts.

14:30         2859.     Dyadic Wavelet-Based Image Noise Suppression and Enhancement in High-Speed Cardiac MR Parallel Acquisition

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Qi Duan¹, Jian Chen¹, Andrew Francis Laine¹, Vinay M. Pai²

¹Columbia University, New York, New York, USA; ²SUNY Upstate Medical University, Syracuse, New York, USA

An automated integrated denoising/enhancing approach was applied to images acquired by parallel acquisition techniques in cardiac imaging. In comparison with previous denoising only framework, this new proposed method could future increase the CNR of the denoised images. Quantitative evaluation on phantom and clinical data confirmed the benefit of this new method in terms of improving CNR on parallel MR images. Preliminary results suggested that this new integrated denoising/enhancing framework could further push the limits on the temporal resolution by improving the SNR and CNR simultaneously.

15:00         2860.     3D Right Ventricular Strain and Geometry in Pulmonary Hypertension and Normals

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Bharath Ambale¹, Steven Lloyd², Thomas Stewart Denney Jr.¹, Louis Dell'Italia², Raymond Benza², Himanshu Gupta²

¹Auburn University, Auburn, Alabama, USA; ²University of Alabama at Birmingham, Birmingham, Alabama, USA

Accurate assessment of right ventricular (RV) function is clinically important – particularly in pulmonary hypertension (PHTN).  Compared to the left ventricle (LV), however, analysis of RV function is relatively difficult.  Unlike the LV, the RV does not have geometric symmetry, precluding use of simple geometric models to calculate RV volumes and wall stress.  Also, in PHTN, higher systolic blood pressure in the RV can cause excursion of the interventricular septum into the LV cavity.  As a result, the LV cavity can also lose its geometric symmetry.  This abstract presents methods for reconstructing three-dimensional biventricular geometry and strain in both normal volunteers and PTN patients.

13:30         2861.     Direct Quantification of 3-D Myocardial Principal Strain Orientations: A New Insight Into Heart Regional Function Abnormality

Computer 2

Khaled Zakarya Abd-Elmoniem¹, Matthias Stuber¹, Amr A. Youssef¹, Tetsuo Sasano¹, Theodore P. Abraham¹, Xiaofeng Lui¹, Sandeep Mullur¹, Evert-Jan P. A. Vonken¹, M. Roselle Abraham¹, Jerry L. Prince¹

¹The Johns Hopkins University, Baltimore, Maryland, USA

We present afast algorithm for direct and complete characterization of 3-D time-course of principle strain orientations using data acquired with zHARP imaging protocol from SA slices without the need for LA data. Using this scheme, two or more SA slices are acquired and processed using zHARP and the 3-D strain tensor and principal strain angles are calculated.  Results from infarct swine model shows that strain orientations time-course can provide more information about heart dynamics, especially when combined with efficient 3-D motion imaging.

14:00         2862.     Quantification of Myocardial Strain at Early Systole in Mouse Heart:  Restoration of Undeformed Tagging Grid with Single Point HARP

Computer 2

Wei Li¹, Jia Zhong², Xin Yu²

¹Case Western Reserve University, Cleveland , Ohio, USA; ²Case Western Reserve University, Cleveland, Ohio, USA

Current MRI tagging analysis often employs the first tagging image as the reference frame. However, for a mouse heart, the first tagging image is frequently acquired at early systole with significant tag line deformation due to fast heart rate. In this study, a HARP-based method was develop to generate an undeformed tagging grids. Myocardial deformation at early systole was analyzed using this method.

14:30         2863.     Noise Measurement in Real-Time Cardiac Cine MRI Using Eigenvalues of Karhunen-Loeve Transform

Computer 2

Yu Ding¹, Yiu-Cho Chung², Subha V. Raman³, Orlando P. Simonetti³

¹The Ohio State University, Columbus, Ohio, USA; ²Siemens Medical Solutions, Inc., Columbus, Ohio, USA; ³The Ohio State University, Columbus, Ohio, USA

Noise measurement is difficult in real-time cine MRI using parallel acquisition techniques because of cardiac and respiratory motion and the spatially variant nature of both signal and noise.  In this work, we investigate using eigenvalues derived from the Karhunen-Loeve Transform to assess mean noise standard deviation in dynamic MR cardiac images. This method may have general application in the evaluation of dynamic imaging methods, and other situations other methods of noise measurement are difficult to apply.

15:00         2864.     DENSE-MR-Elastography for Cardiac Application

Computer 2

Benjamin Robert¹, Ralph Sinkus¹, Jean-Luc Gennisson¹, Mathias Fink¹

¹Laboratoire Ondes et Acoustique, Paris, France

Imaging of mechanical shear waves via MR-Elastography (MRE) allows the assessment of inherent viscoelastic tissue parameters. Cardiac MRE poses several technical challenges: small relaxation times, time dependant viscoelastic properties during the heart beat, respiratory motion. To overcome the short relaxation time and the externally induced mechanical wave problems, a MRE sequence has been adapted from a DENSE sequence.

MRA -Other Techniques

13:30         2865.     Increased Volume of Coverage for Abdominal Contrast-Enhanced MRA with 2D Autocalibrating Parallel Imaging: Initial Experience at 3.0T

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Darren Lum¹, Reed Busse², Christopher Francois¹, Anja Brau³, Philip Beatty³, Joshua Huff¹, Jean Brittain², Scott Reeder¹

¹University of Wisconsin - Madison, Madison, Wisconsin, USA; ²GE Healthcare, Madison, Wisconsin, USA; ³GE Healthcare, Menlo Park, California , USA

We utilize a 2D parallel imaging method (Autocalibrating Reconstruction for Cartesian sampling - ARC) with 3D contrast enhanced MRA for complete abdominal coverage within a breath hold.  An intra-individual comparison study between both parallel imaging accelerated and non-accelerated exams was performed in 6 healthy volunteers.  In addition 8 consecutive patients were evaluated with 2D-ARC MRA.  We find that the subjective image quality of exams with 2D-ARC to be essentially equivalent to those acquired without parallel imaging.  However, the 2D-ARC sequence provided a 3.5 fold increase in imaging volume and a 30% reduction in voxel size in the same acquisition time.

14:00         2866.     Whole-Body MR Angiography with Parallel Imaging – Benefit of a Dedicated 32 Channel Whole-Body MR Scanner Equipped with a Matrix Coil System at 1.5 and 3.0 Tesla

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Harald Kramer¹, Konstantin Nikolaou¹, Henrik J. Michaely², Christian Glaser¹, Maximilian F. Reiser¹

¹University Hospitals Munich - Grosshadern Campus, Munich, Germany; ²University Hospital Mannheim, Mannheim, Germany

Atherosclerosis is a systemic vessel disease. MRI offers the possibility of whole body MRA with excellent image quality and without ionizing radiation. First attempts to WB MRA suffered from MR system Hardware restrictions, recent developments in MR Hard- and Software like parallel imaging, dedicated coil systems and higher field strength helped to increase image quality of WB MRA exams significantly.

14:30         2867.     Comparison of Scoutless EZ-STEP and Conventional Contrast Enhanced Magnetic Resonance Angiography in Thoracic Aorta at 3T

Computer 3

Xiaohai Ma¹,², Zhaoqi Zhang¹, Yi He¹, Zhanming Fan¹

¹Beijing Anzhen Hospital, Beijing, People's Republic of China; ²Michigan State University, East Lansing, USA

Compared to conventional CE-MRA, EZ-STEP is a timesaving method for thoracic aorta imaging in 3T MR scanner, and also provides comparable image quality.

15:00         2868.     Calculating Peripheral MRA Bolus Timing Using Cine-Phase Contrast Flow Measurements

Computer 3

Grace Choi¹, Ryan Brown¹, Minh Chao¹, Yi Wang¹, Martin R. Prince¹

¹Cornell University - Weill Cornell Medical College, New York, USA

Total Gadolinium dose can be reduced on whole body and peripheral MRA by using 2D cine phase contrast MRA to calculate bolus velocity at 7 locations along the arterial tree.  Accuracy of this approach was confirmed by comparison to bolus transit measurements from 1.8s temporal resolution time-resolved MRA.  Example cases show diagnostic peripheral MRA with single dose gadolinium based contrast agent. These data also show a 2-fold reduction in bolus transit time with venous compression applied to thighs.

Time-resolved (YD) MRA

13:30         2869.     High Spatial and Temporal Resolution MRA of the Entire Peripheral Vascular System Using a New 3D Time-Resolved MRA Technique (TWIST)

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Florian M. Vogt¹, Stefan Maderwald¹, Knut Kroeger¹, Gerhard Laub², Randall Kroeker³, Joerg Barkhausen¹, Harald H. Quick¹

¹University Hospital, Essen, Germany; ²University of California Los Angeles, Los Angeles, California , USA; ³Siemens Medical Solutions, USA

Purpose was to develop a triple injection scan protocol for dynamic, high-resolution, isotropic MRA of the entire peripheral vascular system applying a recently developed time-resolved 3D MRA sequence (TWIST). Ten patients with PAD underwent contrast-enhanced MRA collecting dynamic 3D data sets at three consecutive stations. Catheter-based DSA served as standard of reference. For corresponding segments, the number of visible segments was equal to DSA. TWIST MRA provided identical functional information in regions with reduced arterial blood flow or increased venous enhancement. TWIST-MRA is a robust technique that combines functional with high spatial morphological information of the entire peripheral vascular system.

14:00         2870.     Leg MR Angiography with Cuff-Compression: Quantitative Dynamic Analysis

Computer 4

Marcel Koenigkam Santos¹, Puneet Sharma¹, Bobby Kalb¹, John Oshinski¹, Diego Martin¹

¹Emory University, Atlanta, USA

The purpose of this study is to evaluate quantitatively the effect of mid-femoral cuff compression on arterial inflow and venous outflow kinetics using high temporal resolution 3D CE-MRA of the calves. The arterial in-flow time was significantly reduced on the pressure cuff side in comparison to the control side and, in 2 of 4 subjects, no increased signal (above background) was observed in the veins with the pressure cuff after 300 seconds. Our findings quantitatively evaluate the delay in venous filling and indirectly show that this results from multi-factorial events that occur subsequent to supravenous-subarterial blood pressure cuff inflation.

14:30         2871.     Cartesian Acquisition with Projection-Reconstruction-Like Sampling (CAPR): An Optimum Sequence for Time-Resolved CE-MRA

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Clifton R. Haider¹, Houchun Harry Hu², Nobert G. Campeau¹, John Huston¹, Stephen J. Riederer¹

¹Mayo Clinic, Rochester, Minnesota, USA; ²Univ. of Southern California, California , USA

In time-resolved acquisitions there is a need for both high temporal and spatial resolution. The purpose of this work is to describe the incorporation of 2D SENSE acceleration into a view-shared CArtesian Projection Reconstruction-like (CAPR) acquisition, yielding a time-resolved sequence which has high SNR robustness, a high level of consistency, and high temporal fidelity. The sequence is capable of 1 mm3 isotropic resolution with sufficient temporal resolution to distinguish intracranial arterial and venous phases of contrast passage in whole-brain angiography.

15:00         2872.     Comprehensive Magnetic Resonance Imaging of Hands Vasculature at 3 Tesla: Preliminary Clinical Results

Computer 4

Ugur Bozlar¹,², Patrick T. Norton¹, Ahmed Mohamed Housseini¹,³, Thomas Huerta¹, Hendricks E. Daniel¹, Bobby Chhabra¹, David B. Drake¹, Peter B. Arnold¹, Klaus D. Hagspiel¹

¹University of Virginia Health System, Charlottesville, USA; ²Gulhane Military Medical Academy, Ankara, Turkey; ³Suez Canal University, Ismailia , Egypt

Comprehensive MR evaluation of the vasculature of the hand employing high resolution time resolved contrast enhance MRA (tr-ceMRA) and volume interpolated breath-hold examination (VIBE) was performed in patients with clinical symptoms attributable to vascular etiologies. This combine complimentary approach requires a single 20ml administration of contrast agent and utilizes the power of arterial-venous separation provided by the tr-ceMRA and high contrast to noise ratio of the VIBE sequence to allow for assessment of both proximal and distal arterial vessels of the hand. To the best of our knowledge, there is no published study which evaluates the hand vasculature at 3T in such a population.

13:30         2873.     4D Dynamic Contrast Enhanced MRA of the Pulmonary Vasculature with Isotropic Resolution Using a Combination of GRAPPA and TWIST Acceleration

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Robert C. Gilkeson¹,², Martin Blaimer³, Randall Kroeker⁴, Gerhard Laub⁴, Jeffrey L. Duerk¹,², Jeffrey L. Sunshine¹,², Robert O. Schilz², Mark A. Griswold¹,²

¹Case Western Reserve University, Cleveland, Ohio, USA; ²University Hopitals of Cleveland, Cleveland, Ohio, USA; ³University of Wuerzburg, Wuerzburg, Germany; ⁴Siemens Medical Solutions, Germany

14:00         2874.     Time-Resolved 3D MR-Angiography of the Thoracic Aorta at 3 Tesla: Comparison of First-Pass Imaging Characteristics of a Low Albumin-Binding and a Blood-Pool Contrast Agent

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Alex Frydrychowicz¹, Maximilian F. Russe¹, Aurélien F. Stalder¹, Alexander Berger¹, Andreas Harloff¹, Raoul Arnold¹, Mathias Langer¹, Jürgen Hennig¹, Michael Markl¹

¹University Hospital Freiburg, Freiburg, Germany

Gadofosveset trisodium has reached approval for diagnostic purposes in Europe as the first gadolinium-based blood-pool contrast agent. Its imaging characteristics have not been fully evaluated with respect to imaging at 3T and during time-resolved 3D MR-angiography. Therefore, it was the purpose of this study to compare the first-pass imaging characteristics of a blood-pool contrast agent (BPA) to a low albumin-binding standard contrast agent (SCA) in time-resolved contrast-enhanced 3-dimensional MR angiography (tr-CE-MRA) at 3T. Results show that first-pass imaging characteristics of the blood-pool agent are equally well suited for tr-CE-MRA at 3T.

14:30         2875.     Contrast-Enhanced MR Angiography Using Time-Resolved Interleaved Projection Sampling Along the 3D Cartesian Phase and Slice Encodings (TRIPPS)

Computer 5

Jiang Du¹, Nick Pinto¹, Michael S. Middleton¹, Claude Sirlin¹, Graeme M. Bydder¹

¹University of California, San Diego, San Diego, California , USA

Contrast-enhanced three-dimensional (3D) magnetic resonance angiography (CE-MRA) is a useful noninvasive method for evaluating the vascular system. Time-resolved imaging is of great importance in providing contrast dynamics and eliminating contrast timing. Here we present a novel technique called time-resolved interleaved projection sampling along the 3D Cartesian phase and slice encodings (TRIPPS), which is robust and provides high spatial and temporal resolution 3D images with minimal undersampling artifact.

15:00         2876.     The Effect of Time-Resolved K-Space Sampling on Contrast-Enhanced MRA: A Method to Optimize Imaging Parameters

Computer 5

Ting Song¹, Pippa Storey², Qun Chen², Henry Rusinek², Ruth Lim², Andrew F. Laine¹, Vivian S. Lee²

¹Columbia University, New York, New York, USA; ²NYU School of Medicine, New York, New York, USA

We have analyzed k-space sampling strategies for time-resolved MRA by studying the effects of varying (a) the center area of k-space assumed to be fully sampled and (b) the sampling density of k-space periphery. Outcome measures consist of vessel ringing artifacts and diameter measurement accuracy. Overall, we observed that for smaller vessels, higher sampling density of k-space periphery is more important than the size of the fully sampled center area, while for larger vessels, larger center areas gave better accuracy of diameter resolving ability.

13:30         2877.     Controlled Experimental Study Depicting Moving Objects in View-Shared Time-Resolved 3D MRA

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Petrice Marie Mostardi¹, Clifton R. Haider¹, Phil J. Rossman¹, Stephen J. Riederer¹

¹Mayo Clinic, Rochester, Minnesota, USA

The purpose of this work was to develop and use a computer-controlled motion phantom for study of the fidelity with which 3D time-resolved sequences with view-sharing can portray dynamic phenomena.  This allowed determination not only of such properties as ghosting, blurring, and undesired vascular enhancement, but also the fidelity of portraying a rapid influx of contrast into a vessel as well as the smooth passage of contrast across an extended field of view.  These studies helped to identify desirable characteristics of a pulse sequence used for time-resolved studies.

14:00         2878.     Three-Dimensional Time-Resolved Flow Quantification with Balanced SSFP

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Francesco Santini¹, Stephan G. Wetzel², Klaus Scheffler¹

¹University of Basel/University Hospital, Basel, Switzerland; ²Basel University Hospital, Basel, Switzerland

Balanced SSFP sequences do not suffer from spin saturation effects that result in signal loss for tissues with long T1. Their contrast is therefore optimal for the imaging of fluids (blood and CSF) and flow quantification, especially when inflow enhancement effects cannot be exploited, as in three-dimensional sequences. In this work, a three-dimensional, three-directional time-resolved phase contrast bSSFP sequence is presented, along with methods to minimize the artifacts commonly associated with bSSFP sequences, and the application to the study of cerebro-spinal fluid circulation is demonstrated.

14:30         2879.     Femoral Artery Compression in the Adductor Canal During Isometric Thigh Contraction Using a Rapid 3D Steady-State Free Precession Acquisition

Computer 6

Ryan Brown¹,², Thanh Nguyen¹, Martin R. Prince¹, Yi Wang¹,²

¹Weill Medical College of Cornell University, New York, USA; ²Weill Graduate School of Medical Sciences of Cornell University, New York, USA

A rapid 3D steady-state free precession (SSFP) sequence was implemented to image the femoral artery. A long section (15-20 cm) of artery was imaged during isometric thigh contraction to analyze artery compression. Sufficient resolution and contrast to visualize the artery lumen were achieved in a short scan time (approximately 22 sec), which was required for minimal motion artifacts during thigh contraction. Significant artery compression was observed in the adductor canal region, while the artery was less disturbed inferior and superior to the adductor canal.

15:00         2880.     Quantification of Hemodynamics in Abdominal Aortic Aneurysms During Rest and Exercise Using Magnetic Resonance Imaging and Computational Fluid Dynamics

Computer 6

Andrea Seba Les¹, Carlos Alberto Figueroa¹, Mary Therese Draney Blomme¹, Maureen M. Tedesco¹, Jinha M. Park¹, Adrianne Thompson¹, Ronald L. Dalman¹, Robert J. Herfkens¹, Charles A. Taylor¹

¹Stanford University, Stanford, California , USA

We hypothesize that exercise may slow the growth of abdominal aortic aneurysms (AAAs). A gadolinium-enhanced magnetic resonance angiography sequence (MRA) was used to image the aortas of three males with small AAAs using a 1.5T scanner. Infrarenal and supraceliac aortic blood velocities were also measured using a cardiac-gated phase contrast (PC-MRI) sequence. Blood flow was simulated by solving the Navier-Stokes equations on finite-element meshes generated from the MRA and using rest and exercise boundary conditions specified from the PC-MRI data. Mean wall shear stress was calculated at four locations. Infrarenal volumetric flow waveforms obtained from simulation and PC-MRI were compared.

Animal Cardiovascular Imaging

13:30         2881.     Multiple-Mouse Self-Gated Cardiac Cine MRI with Multiple Arrays of Receive Coils (MARCs)

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Emilio Esparza-Coss¹, Marc Stephen Ramirez¹, James Andrew Bankson¹

¹The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA

Simultaneous multiple-animal, self-gated cardiac cine MRI has been shown to drastically improve the imaging efficiency in small animal models of cardiac disease. Here we propose that further improvements can be achieved by dedicating a phased-array coil to each animal to increased SNR and achieve parallel imaging acceleration. Self-gated cardiac cine data was acquired with a four-channel spoiled gradient echo pulse sequence developed to acquire navigator information before application of readout gradients.  Preliminary results indicate that accelerated self-gated cardiac cine MRI using phased-array coils is both feasible and desirable since SNR enhancement can be achieved by averaging oversampled data.

14:00         2882.     Microembolization Contributes to Acute and Subacute Left Ventricular Dysfunction: MR Assessment of Left Ventricular Function and Strain

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Marcus Carlsson¹, Alastair J. Martin¹, Mark Wilson¹, Loi Do¹, David Saloner¹, Maythem Saeed¹

¹University of California San Francisco, San Francisco, California , USA

Microembolization causes microinfarction in patients with unstable angina pectoris and following PCI and CABG. It thought to explain part of decreased ejection fraction in patients. In this study, microembolization was simulated by selective injection of embolic agents in LAD. Cine and tagging MR imaging was used to assess the acute and subacute effects of microembolization on LV volumes, ejection fraction, systolic wall thickening and strain. Cine MRI showed persistent decline in wall thickening and strain associated with increased LV volumes and decreased EF; markers of LV remodeling. Thus, microembolization could be the cause of LV dysfunction in patients.

14:30         2883.     Self-Gated MR Cardiac Imaging of Developing Chick Embryos in the Egg

Computer 7

William Matthew Holmes¹, Christopher McCabe¹, Barrie Condon¹, Jim M. Mullin¹, Maureen M. Bain¹

¹University of Glasgow, Glasgow, UK

The chick embryo is a well-known animal model for cardiovascular research.  The lack of MRI application to chick embryos is partly due to the difficultly of monitoring chick ECG and respiration signals, which are conventionally essential in acquiring images free of motion artefact. In this study we remove these obstacles by employing a self-gated multi-slice CINE MRI protocol that incorporates a navigator-based retrospective gating technique, making possible for the first time cardiac MRI images of a chick embryo inside the egg.

15:00         2884.     Retrospective Gating Strategies for Small Animal MR Imaging at 9.4 Tesla

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S David Smith¹,², Shams Rashid³, Mark Wagshul³, Mei Yu¹, Helene Benveniste¹,³

¹Brookhaven National Laboratory, Upton, New York, USA; ²SA Instruments, Inc, Stony Brook, New York, USA; ³SUNY at Stony Brook, Stony Brook, New York, USA

A Data acquistion system with application software has been developed allowing the retrospective reodering of acquired MR data prior to reconstruction, and is used for the Cardiac Imaging of mice on a 9.4 T Bruker MRI system.  Waveforms for respiratory, Electrocardiogram, Blood pressure and Peripheral pulse measurements were acquired simultaneously to the MRI acquisiton, thereby allowing the same MRI dataset to be reconstructed using reodering schemes based upon each of the different physiological waveforms.  Quantitative evaluation of the cine images made using each of the monitoring waveforms is presented. Advanced strategies refining the reordering using data from multiple waveforms is also presented.

13:30         2885.     MRI Tagging of in Vivo Ventricular Function Reflects Histological and Cellular Changes in α-Dystrobrevin Knockout Mice

Computer 8

Wei Li¹,², Wei Liu³, Allen Ye⁴, Priyanajana Chaudhuri⁴, Suhanti Banerjee⁴, Xin Yu,²⁴

¹Case Western Reserve University, Cleveland , Ohio, USA; ²Cleveland, Ohio, USA; ³Philips Research North America, Bariarcliff Manor, New York, USA; ⁴Case Western Reserve University, Cleveland, Ohio, USA

Dystrophin-glycoprotein complex (DGC) maintains the structural integrity of myocardium. It also plays important signaling roles through nNOS.  α-Dystrobrevin deficiency leads to nNOS displacement from DGC, leading to the development of cardiac lesions at an older age. In the current study, the impact of impaired DGC signaling and the development of cardiac lesions on in vivo ventricular function was examined with MRI tagging in α-dystrobrevin knockout mice. Potential mechanisms responsible for altered ventricular function were explored by histological and cellular studies.

14:00         2886.     Functional Cardiac Phenotyping of Vasoactive Intestinal Peptide (VIP) Deficient Mice by MR Microscopy

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S. David Smith¹, Anthony Szema², Sami I. Said², Helene Benveniste¹,²

¹Brookhaven National Laboratory, Upton, New York, USA; ²Stony Brook University, Stony Brook, New York, USA

Mice with deletion of the gene for VIP exhibit spontaneous pulmonary arterial hypertension (PAH) and vessel remodeling in the absence of hypoxemia with pathology showing thickened pulmonary vessels. We hypothesized that VIP deficient mice with known spontaneous PAH would also develop a decreased functional capacity of their right ventricle. We tested this hypothesis using MR microscopy. Quantitative analysis of cardiac MR microscopy images of VIP deficient mice revealed dilated right ventricles and reduced ejection fractions.

14:30         2887.     Effect of Iron Oxides on Tag MRI at 1.5T in a Rat Myocardial Infarct Model

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Jean-Luc Daire¹, Jean-Noel Hyacinthe¹, Karin Montet-Abou¹, Jean-Pascal Jacob¹, Denis Morel¹, Jean-Paul Vallée¹, Xavier Montet¹

¹Geneva University Hospital, Geneva, Switzerland

This paper proves that despite high accumulation of iron oxides in myocardium infarct, Tag MRI at 1.5T can be realized and analysed in small rodent. The observed defect of contraction in circumferential strains corresponds to the hypointense region containing iron oxides.

15:00         2888.     A Spiral K-Space Trajectory Enables Phase Contrast Measurements of Blood Flow in Curved Sections of the Mouse Aorta

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Robert L. Janiczek¹, Brett R. Blackman¹, R. Jack Roy¹, Scott T. Acton¹, Craig H. Meyer¹, Frederick H. Epstein¹

¹University of Virginia, Charlottesville, Virginia , USA

Conventional rectilinear k-space trajectories can result in displacement artifacts due to movement of spins between excitation and data acquisition, and signal loss due to phase dispersion. Spiral trajectories have long been used for human MRI due to their desirable flow characteristics caused by their short echo-times and low gradient moments. However, these methods have yet to be applied to imaging small animals on high-field small-bore MRI systems. We present phase-contrast data at 7T in the mouse aorta and demonstrates these advantages allow PC data to be obtained in more regions of the mouse vasculature than a rectilinear trajectory.

13:30         2889.     Effect of SEA0400 on Cardiac Mn²⁺ Efflux Rates, Using T₁-Mapping Manganese-Enhanced MRI (MEMRI) in a Murine Model
[Not Available]

Computer 9

Ben Waghorn¹,², Yuhui Yang², Brianna Klein², Akemichi Baba³, Toshio Matsuda³, Nathan Yanasak², Tom Hu²

¹Georgia Institute of Technology, Augusta, Georgia, USA; ²Medical College of Georgia, Augusta, Georgia, USA; ³Osaka University, Osaka, Japan

The Na⁺/Ca²⁺ exchanger (NCX) is an important transporter for the regulation of intracellular Ca²⁺ concentration.  This study uses T₁-mapping of murine cardiac Manganese-Enhanced MRI to quantitatively assess the rate of signal decay post Mn²⁺ infusion. A 50% attenuation of the signal in the left ventricular free wall, normally enhanced by Mn²⁺, is observed within approximately 2.5 hours post infusion. By inhibiting the NCX with SEA0400, we can proceed to characterize a trend of Mn²⁺ efflux modulation. Future work to study the actions of the NCX in detail will be undertaken using various pharmaceutical agents.

Non-Contrast Enhanced MRA

13:30         2890.     The Non-Contrast-Enhanced Hepatic MR Angiography with True Steady-State Free-Precession and Time Spatial Labeling Inversion Pulse: Optimization of the Technique and Preliminary Results

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Kotaro Shimada¹, Hiroyoshi Isoda², Tomohisa Okada², Yoji Maetani², Shigeki Arizono², Yuusuke Hirokawa², Toshikazu Kamae², Kaori Togashi²

¹Kyoto University Graduate School of Medicine , Kyoto, Japan; ²Kyoto University Graduate School of Medicine, Kyoto, Japan

Our purpose is to delineate the hepatic arteries selectively by using respiratory-triggered three-dimensional true steady-state free-precession with time spatial labeling inversion pulse (T-SLIP). T-SLIP is a kind of arterial spin labeling which can provide quantitative and selective inflow information by placing the inversion pulse at any place independent of the imaging area before data acquisition and suppress background signal. 21 healthy volunteers were examined. As a result, selective and high contrast visualization of the hepatic arteries was acquired in 20 cases without exogenous contrast agent. We report our initial experience and describe the optimization of this protocol.

14:00         2891.     Renal Artery MRA at 3.0T: Initial Clinical Experience with Respiratory-Triggered Non-Contrast-Enhanced Phase Contrast with Vastly Under-Sampled Isotropic Projection Reconstruction (PC-VIPR)

Computer 1

Darren Lum¹, Christopher Francois¹, Kevin Johnson¹, Scott Reeder¹, Oliver Wieben¹, Thomas Grist¹

¹University of Wisconsin - Madison, Madison, Wisconsin, USA

In this study, we present our initial clinical experience with respiratory-triggered, non-contrast enhanced PC-VIPR MRA of the abdominal vessels at 3.0T.  We demonstrate comparable image quality between PC-VIPR and 3D contrast enhanced MRA.  Furthermore, PC-VIPR provides improved conspicuity of the segmental renal arteries due to the subtraction of stationary background tissues.  Finally, we find good agreement between the two techniques for measurements of vessel diameter.  In patients who cannot receive contrast secondary to the risk of nephrogenic systemic fibrosis, PC-VIPR may serve as an alternative to abdominal 3D contrast enhanced MRA. Further validation and optimization of this technique is ongoing.

14:30         2892.     ECG Triggered Acquisition Non-Contrast Enhanced (TRANCE) MRA at 3.0Tesla in Peripheral MRA

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Takeshi Ishimoto¹, Takayuki Ikeda¹, Naomi Yamamoto¹, momoe Kawakami¹, Masaru Ishihara², Eiji Okamoto³, Tomoyuki Okuaki⁴

¹Hyogo Brain and Heart Center, Himeji, Japan; ²Hyogo Prefectural Kakogawa Hospital, Kakogawa, Japan; ³Philips Electronics Japan, LTD., Osaka, Japan; ⁴Philips Electronics Japan, LTD., Minato-ku, Japan

Recently, non-contrast enhanced MRA techniques were clinically useful and widely use in routine examination, rapidly gaining in clinical importance. The purpose of this study was to evaluation the technical feasibility and clinical utility of ECG triggered acquisition Non-Contrast Enhanced (TRANCE) MRA at 3.0Tesla in patients with peripheral vascular disease. In peripheral MRA, TRANCE MRA at 3.0Tesla provided diagnostic images comparable with those of CTA and DSA without the administration of contrast agent. This technique will be noninvasive standard examination in the diagnosis of peripheral vascular disease as well as 1.5Tesla.

15:00         2893.     Visualization of the Lenticulostriate Artery with Flow-Sensitive Black-Blood Imaging in Comparison with Time-Of-Flight MR Angiography [Not Available]

Computer 1

K. Gotoh¹, T. Okada¹, Y. Miki¹, M. Ikedo², A. Ninomiya², T. Kamae¹, K. Togashi¹

¹Kyoto University Graduate School of Medicine, Kyoto, Japan; ²Toshiba Medical Systems, Ohtawara, Japan

We visualized lenticulostriate arteries (LSAs) by using Flow-sensitive Black Blood (FSBB) method, which is a variant of 3D-FE (field echo) and make it possible to attenuate the signal of arteries by applying very weak motion probing gradients to disturb refocusing of moving spins only. We compared FSBB with TOF on visualzed LSAs of 19 volunteers and had good results.

13:30         2894.     Non-Contrast-Enhanced MR Portography Using 3D Inversion Recovery-In Flow Iterative Spatial Saturation Pulses (IR-IFIS) Steady-State Free Precession (FIESTA) [Not Available]

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Motoyuki Katayama¹, Takayuki Masui¹, Kimihiko Sato¹, Hidekazu Seo¹, Megumi Ishii¹, Masayoshi Sugimura¹, Kazuhiko Ito¹, Mitsuharu Miyoshi², Naoyuki Takei², Tetsuji Tsukamoto²

¹Seirei Hamamatsu General Hospital, Hamamatsu, Japan; ²GE Yokogawa Medical Systems. Ltd, Hino, Japan

We optimized the parameters of IFIS FIESTA technique in normal volunteer, and applied this technique to the MR examinations in patients with hepatobiliary disorder. The non-contrast-enhanced 3D IR-IFIS FIESTA technique provides good image quality MR portography. When gadolinium is not usable, this sequence might be an alternative choice of method.

14:00         2895.     T1 Insensitive Background Saturation by Two Inversion Pulses for Flow-Prep Non-Contrast-Agent MR Angiography

Computer 2

Mitsuharu Miyoshi¹, Naoyuki Takei¹, Tetsuji Tsukamoto¹

¹GE Yokogawa Medical Systems, Hino, Japan

Flow-Preparation-pulse (Flow-Prep) is a preparation pulse that enhances flow signal and suppresses stationary signal. This is used for Non-Contrast-Agent MRA in this study. However, the stationary background signals remain because of T1 relaxation between the Flow-Prep preparation and the data acquisition. Although T2-Prep and Spectral IR can suppress the kidney and the fat signals, short-T1 intestinal contents remain high signal background. We developed Flow-Prep with two IR pulses, which enabled T1 insensitive background suppression. Aorta and renal artery signals were depicted in high contrast. Intestinal contents, kidney and fat signals were suppressed homogeneously.

14:30         2896.     Using Phase Contrast MRA for the Diagnosis of Pelvic Congestion Syndrome

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Luis Andres Meneses¹,², Cristian Tejos¹,³, Mario Fava¹, Marcelo Andia¹,³, Moshe Pincu⁴, Jorge Cifuentes⁴, Pablo Irarrazaval¹,³

¹Pontificia Universidad Catolica de Chile, Santiago, Chile; ²Biomedical Imaging Center, Santiago, Chile; ³Biomedical Imaging Center, Santiago, Chile; ⁴Hospital Sotero del Rio, Santiago, Chile

In Pelvic congestion syndrome (PCS) ovarian veins (OV) is characterized by abnormal blood flow. We evaluated the accuracy of flow velocity (measured with PC-MRA) as a diagnostic criterion. We studied 16 OV with PC-MRA and with direct venography (DV) as a reference test. PC-MRA showed the same results as DV for the 12 pathological veins. PC-MRA correctly identified 2 of the 4 normal veins. We believe that in the 2 cases with discrepancy, PC-MRA could to detect an early stage   of the PCS which DV could not to identify. PC-MRA provides useful diagnostic tools for the diagnosis of PCS.

15:00         2897.     Non-Contrast MRA Using ECG-Triggered 3D Valuable Flip Angle Fast Spin Echo for the Vessels of the Pelvis and Legs with Total Imaging Matrix Coil [Not Available]

Computer 2

Satoru Kitano¹, Shinji Hirohashi², Nagaaki Marugami¹, Junko Takahama¹, wataru higashiura¹, Toshiaki Taoka¹, Kimihiko Kichikawa¹

¹Nara Mediacl University, Kashihara, Japan; ²Osaka gyoumeikan Hospital, Osaka, Japan

The purpose of this study is to clearly 3D valuable flip angle TSE with Tim (Total imaging matrix) array coil system can be applied to 3D non contrast body MRA. 5 patients underwent 3D non contrast body MRA in a three step table feed technique. Pelvic, femoral and lower leg MRA were obtained ECG-triggered 3D valuable flip angle TSE (space).  3D non-contrast MRA with Tim coil system is a promising technique in the diagnosis of the arterial vascular system of the vessels of the pelvis and legs.

13:30         2898.     Non-Contrast MRA with FIESTA Using IR-IFIS for Selective Visualization the Renal Arteries [Not Available]

Computer 3

Takayuki Masui¹, Motoyuki Katayama¹, Kimihiko Sato¹, Hidekazu Seo¹, Kazuhiko Ito¹, Hiroki Ikuma¹, Masayoshi Sugimura¹, Naoyuki Takei², Mitsuaharu Miyoshi², Tetsuji Tsukamoto², Megumi Ishii¹, Akihiko Kutsuna¹

¹Seirei Hamamatsu General Hospital, Hamamatsu, Japan; ²GEYMS, Hino, Japan

Non-contrast MRA for the aorta and renal arteries was obtained using respiratory-triggered peripheral-gated 3D FIESTA with Inversion recovery-In Flow Iterative Spatial Saturation pulse (IR-IFIS), based on tagging of the blood in the heart and thoracic aorta, which is running through the abdominal aorta, with background suppression by non-selective inversion pulse. The optimal parameters for normal volunteers were evaluated and the abdominal aorta and renal arteries were successfully visualized. In the patients with suspected renal tumors, contrast MRA provide still better information of the aorta and renal arteries, non contrast MRA has potentials to visualize the selected arteries of interest.

14:00         2899.     Non-Enhanced MR Angiography of the Uterine Vessels; Optimization of the Sequence Parameters

Computer 3

Takashi Koyama¹, Tomohisa Okada², Koji Fujimoto², Toshikazu Kamae², Ayako Niyomiya³, Saori Satou³, Nobuyasu Ichinose³, Kaori Togashi²

¹Kyoto University Hospital, Kyoto, Japan; ²Kyoto University, graduate school of medicine, Kyoto, Japan; ³Toshiba Medical Systems, Tokyo, Japan

The purpose of this study is to evaluate the difference of depiction and contrast of the uterine vessels in different inversion time in non-enhanced MRA utilizing Time-SLIP. Nonenhanced Time-SLIP MRA was performed in eight healthy volunteers combining separately with SSFP and FASE at different TI times. With FASE, images the difference of contrast between arteries and veins dose not significantly differ, although images with longer TI tend to show better depiction of the uterine veins. With SSFP, TI of 1800ms provides best depiction of the both arteries and veins, and best contrast between them.

14:30         2900.     Non-Contrast Time-Resolved 2D Fresh Blood Imaging (FBI) [Not Available]

Computer 3

Mitsue Miyazaki¹,², Toshiro Fukuta², Girish Srinivasan¹, Robert Anderson³, nobuyasu Ichinose², Shinichi Kitane⁴

¹Toshiba Medical Research Institute, Vernon Hills, USA; ²Toshiba Medical Systems Corp., Otawara, Japan; ³Toshiba Medical Research Institute, Ohio, USA; ⁴Toshiba Medical Engineering Co., Japan

With the recent association of gadolinium contrast agent and nephrogenic systemic fibrosis (NSF) disease, there is growing interest in using non-contrast MRA techniques as alternatives for contrast enhanced (CE) MRA. As a result, there have been many non-contrast MRA techniques reported.  However, many of studies were limited to the morphology of the vessel lumen.  In this study, a new non-contrast time-resolved MRA technique, using a keyhole technique and parallel imaging, is proposed to shorten scan time. Furthermore, assessment of the proposed technique was investigated to obtain the peripheral arterial hemodynamic information.

15:00         2901.     Non-Contrast MRA of the Toes Using Time-Spatial Labeling Inversion Pulse (Time-SLIP) and Optimization of Flow-Spoiled Gradient Pulses for the Assessment of Foot Arteries in Flow-Spoiled Fresh Blood Imaging (FBI) [Not Available]

Computer 3

Jun Isogai¹, Mitsue Miyazaki², Takeshi Shimada¹, Hideo Hatakeyama¹, Takashi Yamada¹, Naoto Matsuo¹, Shizuaki Maejima¹, Kenji Yodo³, Tomoko Miyata³

¹Hasuda Hospital, Hasuda, Japan; ²Toshiba Medical Research Institute USA, Illinois, USA; ³Toshiba Medical Systems Corporation, Japan

Visualization of small arteries of the foot and toes is quite difficult in using conventional non-contrast MR angiography (MRA) techniques, including time-of-flight (TOF) and phase contrast MRA, due to tortuous vessels out of plane and slow velocity. In addition, Gadolinium-enhanced MRA has also several problems on an injection rate or the amount of contrast materials. Due to the recent concerns of Gadolinium-related Nephrogenic Systemic Fibrosis (NSF), non-contrast MRA solutions have gained interest. Non-contrast flow-spoiled fresh blood imaging (FBI) and time-spatial labeling inversion pulse (time-SLIP) were investigated for visualization of small arteries of the foot and toes.

13:30         2902.     FBI-Navi for Easy Determination of Diastolic and Systolic Triggering Phases in Non-Contrast Fresh Blood Imaging (FBI) [Not Available]

Computer 4

Naoyuki Furudate¹, Mitsue Miyazaki,¹²

¹Toshiba Medical Systems, Otawara, Japan; ²Toshiba Medical Research Institute USA, Vernon Hills, USA

Due to the recent association of gadolinium contrast agent dose and nephrogenic systemic fibrosis (NSF) disease, there have been increasing interests in MRA examination using non-contrast MRA techniques as alternatives. Cardiac gated FSE-based flow-spoiled fresh blood imaging (FS-FBI), allows separation of arteries from veins in peripheral MRA. To find the suitable systolic and diastolic delays, single-slice multiple phases (ECG-prep) images are acquired. However, the determination of systolic and diastolic triggering delays can be problematic. In this study, we propose a new software algorithm, (FBI-Navi), to determine the diastolic and systolic trigger delays to reduce the operational burden.

14:00         2903.     Optimization of Non-Contrast Renal MRA Using a TI-Prep Scan for Time-Spatial Labeling Pulse (Time-SLIP) in 3D Balanced SSFP [Not Available]

Computer 4

Junji Takahashi¹, Yoshinori Tsuji¹, Yusuke Hamada¹, Takashi Yoshida¹, Sachiko Isono², Ayako Ninomiya², Yoshimori Kassai³, Mitsue Miyazaki,³⁴

¹Toranomon Hospital, Tokyo, Japan; ²Toshiba Medical Systems, Tokyo, Japan; ³Toshiba Medical Systems Corp., Otawara, Japan; ⁴Toshiba Medical Research Institute USA, Vernon Hills, USA

Non-contrast-enhanced renal 3D MRA using time-spatial labeling inversion pulse (time-SLIP) is presented to depict the renal arteries. The contrast between the renal arteries and background signals was best visualized with a black blood inversion time (BBTI) of around 1100 msec. However, the depiction of the smaller renal branches depends on the flow speed in patients. We have applied a 2D BBTI preparation scan, which provides a series of single shot images with different BBTI times, prior to the 3D scan. Good correlation was obtained between the 2D BBTI preparation scan and 3D scan in both volunteers and patients.

14:30         2904.     The Value of CINE Bright Blood Sequences in the Evaluation of Cryptogenic Stroke [Not Available]

Computer 4

Larry Allen Kramer¹, Eduardo J. Matta², Anuradha T. Rao², Durga K. Pai², Khader M. Hasan²

¹University of Texas-Houston, Houston, USA; ²UT-Houston, Houston, USA

Magnetic Resonance Venography (MRV) of the pelvic venous system is utilized to evaluate for occult pelvic venous thrombosis in patients with crytogenic stroke.  Echocardiographic evidence of a right to left shunt and negative clinical exam or lower extremity venous doppler study results in investigation of the pelvic venous system with MRV.  Because of tortuosity of the pelvic venous system and valves flow artifacts are common.   To improve specificity CINE bright blood sequences were utilized to evaluate flow defects seen on the conventional 2D time-of-Flight gradient-echo sequences. Our results show that CINE sequences readily distinguishes clot from flow artifact.

15:00         2905.     Accelerated 3D Phase-Contrast MR Angiography Using Time-Interleaved Autocalibration (TCAL)

Computer 4

Anja C.S. Brau¹, Wei Sun², Philip J. Beatty¹

¹GE Healthcare, Menlo Park, California , USA; ²GE Healthcare, Waukesha, Wisconsin, USA

This work demonstrates the feasibility of time-interleaved autocalibration (TCAL) for improving the imaging efficiency of accelerated 3D PC MRA. By sharing the calibration burden across velocity-encoding measurements, TCAL reduces the calibration time penalty by 4x while retaining robustness to motion and compatibility with PC reconstruction.

13:30         2906.     Non-Contrast Enhanced Renal Artery Angiography with a Respiratory Gated 3D Radial Linear Combination SSFP Sequence

Computer 5

Jessica L. Klaers¹, Kevin M. Johnson¹, Christopher Francois¹, Ethan K. Brodsky¹, Youngkyoo Jung¹, Oliver Wieben¹, Walter F. Block¹

¹University of Wisconsin - Madison, Madison, USA

An ultrashort TR dual-echo 3D radial Linear Combination SSFP (LCSSFP) sequence is used in conjunction with a novel real-time adaptive expiratory respiratory gating method for high resolution renal non-contrast enhanced MRA.  This is especially applicable for use in patients with renal insufficiency in the wake of the recent discovery of the link between Nephrogenic Systemic Fibrosis (NSF) and Gd based contrast agents.  The promising initial results give excellent depiction of the renal arteries, including branch vessels, not typically seen in contrast enhanced exams.

14:00         2907.     Phase Contrast Stack of Stars Imaging

Computer 5

Steven Kecskemeti¹,², Kevin M. Johnson¹, Oliver Wieben¹, Charles Mistretta¹,²

¹University of Wisconsin , Madison, Wisconsin, USA; ²University of Wisconsin - Madison, Madison, Wisconsin, USA

A hybrid radial-Cartesian “stack of stars”(SOS) phase contrast (PC)method has been developed to overcome some of the limitations of conventional Cartesian based PC acquisitions, such as long scan times and artifacts from cardiac pulsatility and intravoxel dephasing.   The PC SOS method can be undersampled without aliasing artifact or a loss of resolution as in the Cartesian method, thereby reducing scan times.   In addition, the distributed nature and low frequency over sampling of this sequence reduces cardiac pulsatility artifacts.  We present results comparing the PC SOS images to those obtained with a clinical Cartesian PC sequence.

14:30         2908.     Non Contrast MRA of Renal Transplant Vasculature Using 3D TrueFISP

Computer 5

Natasha Berg¹, John Joseph Sheehan¹, Xiaoming Bi², Peter J. Weale², Randall Ramsay¹, Renate Jerecic², James C. Carr¹

¹Northwestern University, Chicago, Illinois, USA; ²Siemens Medical Solutions, Chicago, Illinois, USA

Contrast enhanced Magnetic Resonance Angiography (CEMRA) has previously been considered a safe alternative to CTA or conventional angiography in the assessment of the renal transplant patient. However, non contrast techniques may be more desirable in this population due to renal impairment. We examined a novel non contrast MRA (NCMRA) technique using a 3D True FISP sequence with selective inversion pulse to assess the renal vasculature in post-transplant patients.  The NCMRA technique demonstrated equivalent and superior imaging of post-transplant vasculature compared to CEMRA.  This technique may be clinically advantageous for renal transplant patients who are unsuitable candidates for contrast administration.

15:00         2909.     Clinical Evaluation of IR Prepared 3D TrueFISP for Non-Contrast Abdominal Angiography - A Comparison to Ce-MRA

Computer 5

Peter J. Weale¹, Natasha Berg², John Sheehan², Randall Ramsay², James Carr², Renate Jerecic¹, Xiaoming Bi¹

¹Siemens Medical Solutions, Chicago, Illinois, USA; ²Northwestern University, Chicago, Illinois, USA

A qualitative and quantitative comparison in patients referred for MRA of a non-contrast approach to abdominal angiography using a 3D IR prepared TrueFISP sequence with a selective IR preparation with spatial localization independent from the imaging volume.

Myocardial Function: Human Studies

13:30         2910.     Strain Encoding MRI (SENC) for the Quantification of Regional Ventricular Function in Pulmonary Arterial Hypertension

Computer 6

Monda L. Shehata¹,², Lynette Brown¹, Dirk Lossnitzer³, Jens Vogel-Claussen¹, Joao A. C. Lima¹, Reda E. Girgis¹, Paul M. Hassoun¹, David A. Bluemke¹, Nael F. Osman¹

¹Johns Hopkins University, Baltimore, USA; ²Ain Shams University, Cairo, Egypt; ³Universty of Heidelberg, Heidelberg, Germany

Right ventricular function evaluation and monitoring are considered important prognostic factors in many cardiac and/or pulmonary disorders especially pulmonary arterial hypertension (PAH)which eventually leads to RV dysfunction and failure. CMR is a versatile tool for global and regional ventricular function evaluation. Tagging has been used for LV function quantification . However, in RV, this technique is limited by thin wall. Strain encoding (SENC)MR is a technique that applies tags parellel to the imaging plane with narrow tag spacing yielding high spatial resolution images. Using 3T MRI, 5 PAH patients were imaged using SENC to quatify regional longitudinal strain (ELL) in RV and interventricular septum and we compared them to 6 healthy controls. Reduced ELL was noted at anterior RV free wall and septum (p<0.05). SENC MR can provide a rapid tool for RV function quantification and monitoring in PAH patients.

14:00         2911.     Imaging Cardiac Motion and Flow Simultaneously During Exercise Stress Studies Using SPAMM N' EGGS

Computer 6

Smita Sampath¹, John Andrew Derbyshire¹, Maria J. Ledesma-Carbayo, Elliot R. McVeigh¹

¹National Institutes of Health, Bethesda, Maryland, USA

Detecting myocardial mechanical dysfunctions and trans-valvular flow abnormalities during the stress of exercise provides early diagnostic indicators in patients with valvular diseases.  Since these events are transient in nature, the ability to acquire these measurements simultaneously is important.  In this study, we apply a new MR imaging technique called SPAMM n’ EGGS (spatial modulation of magnetization acquisitions with encoded gradients for gauging speed), that combines tagging and phase-contrast imaging principles to provide simultaneous measurements of longitudinal left ventricular compression and trans-mitral chamber blood velocity during exercise stress studies in normal volunteers.

14:30         2912.     Evaluation of CSPAMM with Steady State Free Precession for Myocardial Tagging at 3T

Computer 6

Jean-Noel Hyacinthe¹, Jean-Luc Daire, Joost P.A. Kuijer², Magalie Viallon¹, Pierre-Frederic Keller¹, Pierre Croisille³, Jean-Paul Vallée¹

¹Geneva University Hospital, Geneva, Switzerland; ²VU University Medical Center, Amsterdam, Netherlands; ³Université Claude Bernard lyon 1, Lyon, France

Imaging at 3T, using CSPAMM and/or SSFP are efficient means to improve myocardial tagging. In this study we evaluate the combination of all of them in 6 volunteers and 10 patients. CSPAMM with balanced SSFP at 3T combines gain of absolute CNR from the field strength with improved relative tag contrast, easing thus the post processing, and sensitivity to typical SSFP banding artefacts is drastically reduced. Moreover, the technique shows no loss of accuracy in strain measurements, and an accurate diagnosis was performed in patients.

15:00         2913.     Real-Time Cine Imaging at Peak Exercise Stress with a 32-Channel Cardiac Array, TGRAPPA, and Karhunen-Loeve Image Filtering

Computer 6

Mihaela Jekic¹,², Yu Ding², Eric Foster¹,³, Subha V. Raman¹,², Orlando P. Simonetti¹,²

¹The Ohio State University, Columbus, USA; ²Dorothy M. Davis Heart and Lung Research Institute, Columbus, USA; ³Dorothy M. Davis Heart and Lung Research Institiute, Columbus, USA

Rapid heart rates and heavy breathing associated with exercise stress testing demand higher temporal resolution than is attainable by current methods. Our standard exercise stress protocol utilizes a 12-channel coil and parallel acceleration rate 4, resulting in temporal resolution of approximately 52 msec, but further gain in temporal resolution is desired. We investigated the performance of real-time cardiac imaging immediately after maximal treadmill exercise by the combined application of a 32-channel cardiac array coil, TGRAPPA rate 5 acceleration, and KLT filtering, and quantitatively compared SNR to our standard method. We successfully increased temporal resolution to 43.7 msec without compromising spatial resolution or SNR.

13:30         2914.     Image Based Real-Time Monitoring of Cardiac Parameters for Stress Testing or Interventions

Computer 7

Corinna S. Maier¹,², Peter Kellman³, Michael Bock², Wolfhard Semmler², Christine H. Lorenz⁴

¹Siemens Corporate Research, Princeton, New Jersey, USA; ²German Cancer Research Center (dkfz), Heidelberg, Germany; ³National Institutes of Health, Bethesda, Maryland, USA; ⁴Siemens Corporate Research, Baltimor

The proposed framework provides a method for real-time monitoring and detecting changes for regional and global ejection fraction (EF) and heart rate (HR) during a cardiovascular intervention or dobutamine stress test under MRI. Basal, mid and apical MRI left ventricular (LV) short axis images are acquired. End systolic and end diastolic volumes are estimated in each heart cycle based on the results of an Expectation-Maximization segmentation algorithm. EF and HR are calculated continuously, are corrected and smoothed and a change detection algorithm is applied. Estimated EF and HR are compared to the offline calculated EF and the recorded ECG, respectively.

14:00         2915.     Left Ventricular Internal Flow in Patients with Dyssynchronous Heart Failure: Quantification by Cine MRI

Computer 7

Brandon K. Fornwalt¹,², Patrick C. Gonzales¹, Jana G. Delfino¹,², Robert L. Eisner¹,³, Angel R. León¹,³, John N. Oshinski¹,²

¹Emory University, Atlanta, Georgia, USA; ²Emory/Georgia Institute of Technology, Atlanta, Georgia, USA; ³The Carlyle Fraser Heart Center, Atlanta, Georgia, USA

Better methods to quantify left ventricular dyssynchrony are needed to identify candidates for cardiac resynchronization therapy (CRT). Dyssynchrony creates abnormal displacement of blood within the left ventricle, and this “internal flow” may represent the most direct measure of dyssynchrony. We hypothesized that internal flow could be quantified from cine-MRI and would be increased in patients undergoing CRT compared to controls. Systolic internal flow was 21±10% in 10 patients and 2±2% in 10 controls (p<0.001). A threshold systolic internal flow of 6% discriminated patients from controls with 100% accuracy. MRI-based quantification of ventricular internal flow may be useful in diagnosing dyssynchrony.

14:30         2916.     Saturation-Band Cine MRI Improves Detection of Intracardiac Shunt

Computer 7

Wiphada Patricia Bandettini¹, Andrew Ernest Arai¹

¹National Institutes of Health, Bethesda, Maryland, USA

Saturation-bands interleaved with gradient echo cine MRI provides “tagged” blood, but its use in the assessment of congenital intracardiac shunt has been limited. The technique is easily implemented and can be added to a standard congenital imaging protocol.   The purpose of this study was to demonstrate the utility of adding a saturation pulse to gradient recalled echo cine MRI to assist in the identification and anatomic delineation of  intracardiac shunts.

15:00         2917.     Assessment of Left Ventricular Volume and Mass at 3.0T Using SSFP and FLASH Cine Imaging

Computer 7

Neil Woodhouse¹, Dan Hagger¹, Jim M. Wild¹

¹University of Sheffield, Sheffield, UK

SSFP is the accepted standard for cine imaging of cardiac function at 1.5 T. Recent work at 3T suggests SSFP offers increased contrast to noise ratio (CNR) over spoiled gradient echo methods (FLASH). Left ventricular (LV) measurements were evaluated at 3.0T using SSFP and FLASH sequences in 6 healthy volunteers. Significant differences in both mass and volume were demonstrated between both imaging methods. FLASH systematically overestimated mass and underestimated volume (p<0.05) when compared to SSFP although it was significantly lees affected by magnetic susceptibility artefact. FLASH appears to be the more robust sequence at 3.0T despite having a lower CNR.

MRA Contrast Agents

13:30         2918.     High Resolution Arterial MRA of the Lower Limb by Hybrid K-Space Reconstruction Before and After Administration of Vasovist Bloodpool Constrast Agent

Computer 8

Egbert Gedat¹, Rainer Kirsch², Mojgan Mohajer¹, Bernhard Meyer¹, Bernd Frericks¹

¹Charité Universitätsmedizin Berlin, Berlin, Germany; ²Siemens Medical Solutions, Erlangen, Germany

High resolution CE MRAs of the lower limb were acquired in the steady state phase after administration of bloodpool contrast agent gadofosveset trisodium. To remove the veins and facilitate the assessment of the arteries they were computationally combined with first pass image volumes by replacing central k-space. 18 patients were examined yielding resulting MIPs of the lower limbs’ arteries of good quality for 8 patients. The veins were mostly removed and the high resolution was preserved. For the other patients either the distribution of the contrast agent was inappropriate or patient motion had occurred.

14:00         2919.     MR Phlebography with a Blood Pool Contrast Agent in Patients with Peripheral Arterial Occlusive Disease

Computer 8

Guido Matthias Kukuk¹, Dariusch Reza Hadizadeh¹, Markus Moehlenbruch¹, Kai Wilhelm¹, Arne Koscielny¹, Frauke Verrel¹, Hans Heinz Schild¹, Winfried Albert Willinek¹

¹University of Bonn, Bonn, Germany

Contrast-enhanced MR angiography is routinely used for evaluation of peripheral arterial occlusive disease (PAOD). The introduction of the intravascular contrast agent Gadofosveset Trisodium allows for longer acquisition times with high T1 relaxivity resulting in higher spatial resolution imaging of both arteries and veins during the steady state phase. 139 patients were referred to MRA for evaluation of PAOD at 1.5T. In 46/139 patients (33%) we incidentally found clinically relevant venous diseases including deep vein thrombosis, varicosis or arteriovenous fistula. In conclusion, the combination of MRA and MR phlebography appears to be a promising clinical application for blood pool contrast agents.

14:30         2920.     Gadofosveset-Enhanced Steady State MRA of the Peripheral Vessels with Dixon Fat-Saturation

Computer 8

Henrik Jakob Michaely¹, Ulrike I. Attenberger², Harald Kramer², Maximilian F. Reiser², Stefan O. Schoenberg¹

¹University Hosptial Mannheim, Mannheim, Germany; ²University of Munich, Munich, Germany

In this study the feasibility and image quality of a two-point Dixon MRA during the steady state after the injection of gadofosveset was compared to a MRA with conventional spectral fat-saturation. Using the Dixon technique a significantly higher SNR and CNR were achieved due to a more homogenous fat-suppression than with spectral fat-suppression.

15:00         2921.     Comparison of Renal MRA and Angiography Data in the CORAL Study

Computer 8

Honglei Zhang¹, Alan Matsumoto², Timothy Murphy, Don Cutlip³, Katie Wade³, Christopher J. Cooper⁴, Lance Dworkin⁵, Martin R. Prince¹

¹Weill Medical College of Cornell University, New York, New York, USA; ²Virginia University, USA; ³Harvard Clinical Research Institute, USA; ⁴University of Toledo College of Medicine, Toledo, Ohio, USA

Fifty-five renal MRAs were reviewed by MRA core lab for randomization in to CORAL study, of which 26 (47%) were diagnosed as having > 60% stenosis.  For the 7 randomized to balloon angioplasty and stent therapy, angiography confirmed that MRA correctly identified 8 lesions as hemodynamically significant with an accuracy of 100%.  In 35 MRAs with local reports, MRA readings by coral lab were consistent with the readings by local radiologist in 19 patients (54%).  These included 15 positive studies and 4 negative studies.  In the remaining 16 patients, local radiologists overestimated the severity of renal artery stenoses.

Coronary MRA

13:30         2922.     Whole Heart Coronary MR Angiography Acquired with 32-Channel Cardiac Coils for the Detection of Coronary Artery Disease

Computer 1

Motonori Nagata¹, Hajime Sakuma¹, Nanaka Ishida¹, Tairo Kurita¹, Yoko Mikami¹, Hiroshi Nakajima¹, Katsuya Onishi¹, Masaaki Ito¹, Kan Takeda¹

¹Mie university hospital, Tsu, Japan

Use of 32 channel coils allows for acquisition of whole heart coronary MRA in a reduced imaging time and with high study success rate, which resulted in considerably improved overall detection rate of CAD in subjects who underwent coronary MRA.

14:00         2923.     Signal-To-Noise Ratio Enhancement in Coronary MRA Using Parallel Imaging

Computer 1

Jing Yu¹, Michael Schär¹, Evert-jan P.A. Vonken¹, Sebastian Kelle¹, Matthias Stuber¹

¹Johns Hopkins University, Baltimore, Maryland, USA

Coronary MRA with short acquisition windows is limited by SNR. We propose a method to enhance SNR based on parallel imaging in conjunction with a reduced number of radiofrequency excitations while the scanning time remains unchanged. A practical method to quantify SNR on images obtained with parallel imaging was developed as well. Numerical simulations predict that the SNR gain using the proposed method is greatest for very short acquisition windows. These theoretical findings are in good agreement with in vitro and in vivo results obtained in this study.

14:30         2924.     Contrast-Enhanced MR Angiography: A Helpful Methodology to Detect Coronary Atherosclerotic Plaque

Computer 1

Xihai Zhao¹,², Xin Liu³, Liuquan Cheng², Li Yang², Zulong Cai², Chun Yuan¹

¹Vascular imaging lab. , Seattle, Washington, USA; ²deparment of radiology, Beijing, People's Republic of China; ³Departments of Radiology, Chicago, Illinois, USA

This study focus on using contrast-enhanced MR angiography to improve the SNR and CNR of MR images and to increase the detection rate of coronary atherosclerotic plaque.

15:00         2925.     Contrast-Kinetics-Resolved Whole-Heart Coronary MRA Using 3DPR

Computer 1

Peng Lai¹, Feng Huang², Sonia Nielles-Vallespin³, Xiaoming Bi⁴, Andrew C. Larson¹, Renate Jerecic⁴, Debiao Li¹

¹Northwestern University, Chicago, Illinois, USA; ²Invivo Corporation, Gainesville, Florida, USA; ³Siemens AG Medical Solutions, Erlangen, Germany; ⁴Siemens Medical Solutions, Chicago, Illinois, USA

In contrast-enhanced coronary MRA, a bolus scan is usually necessary to estimate the transit time from contrast injection to peak arterial enhancement. However, optimal timing of data acquisition often remains elusive due to variations of heart rates and respiratory gating efficiency as well as simultaneous myocardial enhancement. In this work a contrast-kinetics-resolved technique using 3DPR was developed which eliminates the tedious planning task and enables retrospective selection of the optimal coronary artery visualization for different coronary artery segments. Also, the center-k-space magnitude change could be used to approximate contrast kinetics during a scan, enabling automatic selection of optimal time frames.

13:30         2926.     Contrast-Enhanced Coronary MR Angiography with Gd-DTPA Slow Infusion

Computer 2

Liuquan Cheng¹, Tao Li¹, Haiyue Ju¹, Xihai Zhao¹,², Yuangui Gao¹, Yi Wang³

¹Chinese PLA General Hospital, Beijing, People's Republic of China; ²Northwestern University Medical School, Chicago, USA; ³Weill Medical College of Cornell University, New York, USA

The navigator-gated FIESTA coronary MRA was acquired during the slow infusion of Gd-DTPA. The SNR and image quality could be improved and it is more accurate than the non-contrast study in stenosis detection.

14:00         2927.     Breath-Hold Whole-Heart Coronary MR Angiography (CMRA) by 2D-Parallel Acquisition Compared with Respiration-Gated CMRA Using a Multi-Element Body Coil

Computer 2

Tomohisa Okada¹, Shotaro Kanao¹, Shigehide Kuhara², Ikuo Aoki², Ayako Ninomiya², Saori Satou², Toshikazu Kamae¹, kimio Gotoh¹, Kaori Togashi¹

¹Kyoto University Graduate School of Medicine, Kyoto, Japan; ²Toshiba Medical Systems Corporation, Ohtawara, Japan

The multi-element phased-array body coil is now widely available in clinical practice. It has capability of 2D-parallel imaging, which may largely reduce scan time. This study investigated the attainable quality of coronary MRA in breath-hold (BH) compared with respiration-gated (RG) CMRA. Examination of 14 healthy subjects resulted in scan time reduction approximately from 12 minutes to 34 seconds. The average quality score of visualization (0-4) was reduced by 0.93, however, proximal segments (#1-2, #5-7, #11) showed average scores over 2, which was considered usable for clinical evaluation.

14:30         2928.     Whole Heart Coronary Vein Imaging

Computer 2

Christian Stoeck¹,², Dana C. Peters², Yuchi Han², Beth Goddu², Warren J. Manning², Sebastian Kozerke³, Reza Nezafat²

¹ETH Zurich, Zurich, Switzerland; ²Beth Israel Deaconess Medical Center Harvard Medical School, Boston, Massachusetts, USA; ³Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland

Transvenous BiV lead implantation in cardiac resynchronization (CRT) therapy is preferred to surgical placement. However, for the transvenous approach, knowledge of the coronary vein anatomy is needed prior or during the implantation procedure. Recent studies showed the strength of cardiovascular MR in assessing coronary vein anatomy. In this study we investigated the use of MT-SSFP whole heart imaging to assess coronary vein anatomy.

15:00         2929.     2D Spin-Labeling Coronary MR-Angiography with Cartesian and Radial K-Space Sampling

Computer 2

Marcus Katoh¹,², Matthias Stuber³, Arno Buecker¹, Rolf W. Gunther², Elmar Spuentrup²,⁴

¹University Hospital Saarland, Homburg, Germany; ²RWTH Aachen University Hospital, Aachen, Germany; ³Johns Hopkins University Medical School, Baltimore, Maryland, USA; ⁴University Hospital Köln, Köln, Germany

3D spin-labeling coronary MR-angiography (cMRA) allows selective visualization of the coronary arteries. This technique is limited by a long scanning time as two 3D data sets must be subtracted. In this study, the value of a 2D approach was investigated. The coronary arteries of 8 volunteers were imaged on a 1.5 T MR-system using a navigator-gated and cardiac-triggered 2D SSFP cMRA sequence with Cartesian and radial k-space sampling. 2D spin-labeling cMRA allowed for selective visualization of the left and right coronary system within a minute. Radial k-space sampling proved to be superior with respect to artifact suppression, SNR, CNR and vessel border definition.

Contrast-Enhanced Myocardial Perfusion Imaging

13:30         2930.     Free Breathing Myocardial Perfusion Using Navigator Slice Tracking and TSENSE

Computer 3

Bryan Kressler¹, Pascal Spincemaille², Thanh D. Nguyen², Jonathan W. Weinsaft², Martin R. Prince², Yi Wang¹

¹Cornell University, Ithaca, USA; ²Weill-Cornell Medical College, New York, USA

Conventional contrast enhanced myocardial perfusion imaging relies on a prolonged breath hold to eliminate respiratory motion.  However, the contrast enhancement time course may be too long for patients to successfully suspend respiration, resulting in breathing motion and rendering image analysis difficult.  In this work, navigator slice tracking is applied to myocardial perfusion, eliminating the need to perform breath holding and enabling acquisition of the entire contrast enhancement time course with minimal breathing motion.  TSENSE acquisition and processing are applied to increase the number of slices that can be acquired.  The technique is demonstrated in healthy volunteers and patients.

14:00         2931.     Dual Bolus Myocardial Stress Perfusion Quantification in Normals

Computer 3

Yi Wang¹,², Raphael Hazel¹, Bin Luo¹, Marguerite Roth¹, Jing Han¹, Nathaniel Reichek¹,²

¹St. Francis Hospital, Roslyn, New York, USA; ²SUNY, Stony Brook, New York, USA

We studied Fermi model-based quantitative perfusion quantification methods in dual bolus myocardial adenosine stress perfusion and evaluated their absolute perfusion values at different dose in 16 normal volunteers.  The results showed significant difference in average perfusion values both under stress (5.64 ml/min/g) and at rest (2.30 ml/min/g) at 0.05mM/kg standard contrast dose versus stress perfusion (2.07 ml/min/g) and rest perfusion (0.69 ml/min/g) when 0.005mM/kg contrast dose blood signal was used as the arterial input function. However, their flow reserves both dual bolus or standard dose only were significantly associated and their means were close (2.49 at SD versus 2.31 at DB). The flow reserve values showed good correlation with subject age and are consistent with PET findings in normals.

14:30         2932.     First-Pass Myocardial Perfusion: Comparison Between Full-Dose Hybrid-EPI and Half-Dose Balanced-SSFP

Computer 3

Peter D. Gatehouse¹, Chiara Bucciarelli-Ducci, Jonathan C. Lyne, David N. Firmin, Dudley J. Pennell

¹Royal Brompton Hospital, London, UK

Comparisons of these sequences at the same dose have shown abundant myocardial SNR for myocardial perfusion balanced SSFP compared to hybrid-EPI, but with more dark-rim subendocardial artefact in bSSFP. This study compared the two sequences for stress perfusion in 8 subjects, using reduced contrast agent dose for bSSFP to reduce one potential source of artefact (B0 distortion). While myocardial SNR with bSSFP remained equivalent or superior to hEPI, dark-rim artefact also occurred in normal segments more frequently in half-dose bSSFP than full-dose hEPI.

15:00         2933.     Myocardial Magnetic Resonance Stress Perfusion Imaging at 3T Using a 1-Molar Contrast Agent

Computer 3

Bernhard Daniel Klumpp¹, Christina Doesch¹, Achim Seeger¹, Joerg Doering¹, Tobias Hoevelborn¹, Ulrich Kramer¹, Michael Fenchel¹, Andreas May¹, Claus D. Claussen¹, Stephan Miller¹

¹Eberhard-Karls-University of Tuebingen, Tuebingen, Germany

Myocardial stress perfusion MR imaging (MRSPI) at 1.5T is limited by low SNR. This can be compensated by an increase of field strength and contrast agent concentration. Aim of our study was the evaluation of MRSPI at 3T using a 1-molar contrast agent. MRSPI was assessed in 57 patients with suspected coronary artery disease (CAD) using a 2D sr GRE sequence (0.1 mmol Gadobutrol / kg BW). Standard of reference was invasive coronary angiography. Sensitivity for coronary artery stenoses >70% was 97%, specificity 81%, diagnostic accuracy 93%. MRSPI under such optimized conditions provides increased sensitivity / specificity for CAD.

13:30         2934.     Myocardial Perfusion Quantification: Effects from Contrast Dose, Imaging Plane and Sequence

Computer 4

Yi Wang¹,², Raphael Hazel¹, Bin Luo¹, Marguerite Roth¹, Jie Jane Cao¹, Nathaniel Reichek¹,²

¹St. Francis Hospital, Roslyn, New York, USA; ²SUNY, Stony Brook, New York, USA

The quantification of myocardial perfusion using MRI is an important research and clinical tool for evaluating ischemia. However, its dependence to contrast dosages, imaging sequences and imaging orientation has not been thoroughly investigated. We studied 14 normal volunteers using a dual bolus approach with 3 different sequences to acquire perfusion images in both long and short axis, and evaluated the regional absolute perfusion values. The objective of this study was to determine whether the resting perfusion quantification using the dual bolus approach is dependent on the MRI pulse sequence or imaging plane orientation.

14:00         2935.     Value of First Pass Perfusion and Delayed Contrast Enhancemed MR Imaging in Detecting Microinfarction: Histopathologic Confirmation

Computer 4

Marcus Carlsson¹, David Saloner¹, Alastair J. Martin¹, Loi Do¹, Juha Koskenvuo¹, Maythem Saeed¹

¹University of California San Francisco, San Francisco, California , USA

Coronary microembolization is a frequent complication of coronary interventions. We determined the effects of microembolization on perfusion and visualization of microinfarction 1hr and 1week after delivery of embolic agents. First pass perfusion and delayed contrast enhanced (CE) MR imaging was used to non-invasively monitor the serial changes in regional perfusion and viability. Histopathology was used to confirm the presence of microinfarction. The embolic agents were visualized in coronary tree surrounded by microinfarction. Acute and subacute microinfarction showed perfusion deficit. CE-MR imaging delineated subacute microinfarction due to the loss of membrane integrity of ischemic myocytes, but not all discrete acute microinfarction.

14:30         2936.     Multislice Single Shot Spin Echo EPI Perfusion Imaging with Zone-Selection and Parallel Imaging

Computer 4

Pedro Ferreira¹, Peter Gatehouse², David Firmin¹, Chiara Bucciarelli-Ducci¹, Ricardo Wage²

¹Imperial College, London, UK; ²Royal Brompton Hospital, UK

Myocardial perfusion images are often affected by a subendocardial Dark Rim Artifact (DRA). A sequence has been designed with the underlying ethos of greater robustness against the DRA, by reducing the echo train length and nulling the signal in the left ventricle blood pool. The sequence is a single-shot spin-echo EPI with zonal excitation and parallel imaging techniques.

Preliminary results show no evidence of myocardial dephasing, or distortion by cardiac motion or field nonuniformity during first pass of contrast agent; although TSENSE is proving challenging to include with saturation recovery due to low SNR.

15:00         2937.     Compressed Sensing Cardiac Perfusion Imaging

Computer 4

Viton Vitanis¹, Robert Manka¹,², Urs Gamper¹, Peter Boesiger¹, Sebastian Kozerke¹

¹ETH Zurich, Zurich, Switzerland; ²German Heart Institute Berlin, Berlin, Germany

This work demonstrates the feasibility of accelerating perfusion imaging using Compressed Sensing and compares the method to k-t SENSE. Based on computer simulations and actual in-vivo measurements it is shown that Compressed Sensing yields lower reconstruction errors up to a net acceleration factor of three. Beyond this factor k-t SENSE outperforms with respect to root-mean-square reconstruction error. The lower error is, however, associated with some temporal low pass filtering of signal-intensity curves. In conclusion, both methods tested seem suitable to accelerate cardiac perfusion imaging up to net acceleration factors of five without compromising signal-intensity perfusion curves significantly.

13:30         2938.     First-Pass Cardiac Perfusion MRI with 50%-Reduced Contrast Agent Dosage

Computer 5

Daniel Kim¹

¹New York University, New York, New York, USA

While first-pass cardiac perfusion MRI is a promising modality for the assessment of coronary artery disease, there are safety concerns associated with Gadolinium-based MRI contrast agents, especially in patients with renal insufficiency. One strategy to reduce the contrast agent dosage is to achieve maximal myocardial contrast-to-noise ratio (CNR) through pulse sequence optimization and trade off a portion of CNR to reduce the dosage. The purpose of this study is to optimize the pulse sequence with optimal k-space trajectory and variable flip angles to achieve comparable image quality at 50%-reduced dosage to that produced by a convention sequence at standard dosage.

14:00         2939.     Perfusion Phantom for Quantitative Imaging

Computer 5

Behzad Ebrahimi¹,², Scott D. Swanson, Timothy E. Chupp,²

¹University of Michigan, Ann Arbor, USA; ²Focus Center, Ann Arbor, USA

A perfusion phantom with unique features and a wide variety of applications in MR and other imaging modalities is presented. The phantom is especially suited to tissue perfusion simulation with diffusible and non-diffusible MR tracers. A network of micro-channels in the scale of actual capillaries replicates the blood flow in tissues. Using microfabrication technique, networks with any desired pattern can be generated. Since the geometry of networks is known, flow rate, delay, dispersion and other fluid parameters can be exactly calculated, using finite elements numerical methods. These calculated results can be used to investigate the accuracy of experimental measurements and the precision of mathematical models.

14:30         2940.     Quantitative Assessment of the Dark Rim Artifact in First Pass Perfusion Images: Effect of Stress and Rest, and Sequence Dependence

Computer 5

Raphael Delano Hazel¹, Nathaniel Reichek¹, Yi Wang¹

¹St Francis Hospital, Roslyn, New York, USA

Dark Rim Artifact (DRA) in Gadolinium enhanced saturation recovery TrueFISP cardiac first pass perfusion images from normal volunteers collected during stress and rest, show similar frequency affecting 12.5% of the rest and 10.2% of stress images, with comparable severity represented by signal loss of 32.9 % (rest) and 31.5 % (stress) in the endocardium. The duration and severity of the DRA coincides with the maximum contrast agent concentration and susceptibility difference between LV and myocardium. A comparison of three pulse sequences shows that TrueFISP is most affected by the DRA, followed by TFL while EPI shows no artifact.

15:00         2941.     The Relationship Between Signal Intensity and Myocardial Gadolinium Concentration for Three MR Perfusion Pulse Sequences: Implications for Measuring Absolute Myocardial Blood Flow

Computer 5

Daniel C. Lee¹,², Nils P. Johnson¹, Kathleen R. Harris¹

¹Northwestern University, Chicago, Illinois, USA

Calculation of absolute myocardial blood flow from magnetic resonance first-pass perfusion studies by deconvolution requires a linear relationship between signal intensity (SI) and gadolinium concentration [Gd] in both the blood pool and the myocardium. We measured this relationship in canine myocardium for three common perfusion pulse sequences. Inversion recovery-prepared single-shot steady-state free-precession demonstrates excellent myocardial signal enhancement and a linear SI-[Gd] relationship. Saturation recovery-prepared segmented echo-planar-imaging and saturation recovery-prepared turbo fast low-angle shot exhibit less robust myocardial signal enhancement and a curvilinear SI-[Gd] relationship. This nonlinear signal response may result in underestimation of absolute myocardial blood flow.

Cardiac Diffusion Tensor Imaging

13:30         2942.     Myofiber Developmental Plasticity in Fetal Hearts Delineated with Diffusion Tensor MRI

Computer 6

Lei Zhang¹, Junjie Chen¹, Allyson Gibson¹, Mark R. Holland¹, Gregory M. Lanza¹, Samuel A. Wickline¹

¹Washington University in St. Louis, St. Louis, Missouri, USA

Cardiac functions in prenatal and postnatal phases are different. We hypothesized that myocardial fiber structures in fetal hearts may also differ from that of the adult hearts. Diffusion tensor MRI was used to delineate myocardial fiber structures in fetal pig hearts. Balanced contributions from both left ventricle and right ventricles to the septal myofibers and a thick right ventricle free wall (RVFW) in fetal hearts were observed. In contrast, adult hearts showed thinner RVFW and a dominant contribution to the septal fibers from left ventricle. These structural differences may reflect the plasticity of myocardial fiber development in response to the programmed differential contractile functions before and after birth.

14:00         2943.     A Study of Variability of the Mouse Myocardial Fiber Structure Obtained by MR Diffusion Tensor Imaging

Computer 6

Yi Jiang¹, Sarang Joshi², Kumar Pandya³, Oliver Smithies³, Edward W. Hsu²

¹Duke University, Durham, North Carolina, USA; ²University of Utah, Salt Lake City, Utah, USA; ³University of North Carolina, Chapel Hill, North Carolina, USA

Principal component analysis (PCA) was used to assess the variability of the mouse myocardial fiber helix angle and fractional anisotropy obtained by MR diffusion tensor imaging (DTI). Leave-one-out tests indicate that structural variability of the normal mouse hearts can be represented by as few as 6 DTI datasets. Moreover, PCA successfully distinguished hypertrophic hearts from the normal group. These findings suggest a rather low degree of intra-group variability and lend validity to atlas-based representation and modeling of the myocardial fiber structure.

14:30         2944.     Diffusion Tensor MRI Reflects Age-Associated Changes in Normal and Cardiomyopathic Syrian Hamsters

Computer 6

Wen Li¹,², Allen Ye¹, Ming Lu¹, Suhanti Banerjee¹, Xin Yu¹

¹Case Western Reserve University, Cleveland, Ohio, USA

The purpose of this study is to explore the potential of diffusion tensor MRI (DTMRI) in evaluating aging and cardiomyopathy (CM)-associated myocardial remodeling in Syrian hamsters.  DTMRI were performed on formalin-fixed hearts of both normal and CM hamsters. Our results suggest that DTMRI is sensitive to microscopic structural changes associated with aging and disease progression.

15:00         2945.     Interspecies Variability in the Myocardial Fiber Structure Acquired Using MR Diffusion Tensor Imaging

Computer 6

Lindsey Healy¹, Sarang Joshi¹,², Yi Jiang³, Edward Hsu¹

¹University of Utah, Salt Lake City, Utah, USA; ²Salt Lake City, USA; ³Duke University, Durham, North Carolina, USA

The variability in the fiber helix angle of mouse, rabbit, and sheep, obtained using MR diffusion tensor imaging (DTI), was assessed using principal component analysis (PCA).  A significant difference was found between each of the rabbit and sheep hearts compared to the mouse hearts.  The sheep and rabbit hearts were not significantly different.  The significant difference between the rabbit and mouse and sheep and mouse hearts suggest that larger hearts cannot be directly scaled down to replace the structure of smaller animals.

Myocardial Viability

13:30         2946.     Quantitative Assessment for Late Gadolinium Enhancement in Normal Myocardium [Not Available]

Computer 7

Atsushi Kono¹,², Naoaki Yamada¹, Masahiro Higashi¹, Suzu Kanzaki¹, Teruo Noguchi¹, Kazuro Sugimura², Hiroaki Naito¹

¹National Cardiovascular Center, Suita, Japan; ²Kobe University Graduate School of Medicine, Kobe, Japan

Current assessment of delayed gadolinium enhancement in myocardium has limitation in detection of diffuse myocardial disease as based on relative signal intensity to the apparently non-enhanced myocardium. Normalization of myocardial signals by lumen signals in delayed enhancement (M/L) is useful to cancel out sensitivity inhomogeneity of surface coil. We demonstrate that normal M/L is invariable in a wide range of time after gadolinium administration, heart rate, hematocrit, and renal function (serum creatinine). On the basis of the results, M/L can detect abnormality of diffuse myocardial disease such as cardiac amyloidosis and Fabry disease.

14:00         2947.     Three Dimensional Phase Sensitive Inversion Recovery (PSIR) TurboFLASH for Evaluation of Left Ventricular Myocardial Scar

Computer 7

Aya Kino¹, John Sheehan¹, Sven Zuehlsdorff², Peter Weale², Xin Liu¹, Randal Ramsey¹, Renate Jerecic², James Carr¹

¹Northwestern University, Chicago, Illinois, USA; ²Siemens Medical Solutions, Chicago, Illinois, USA

Delay enhanced (DE) imaging is a well-established method for detection of myocardial scar. 2D PSIR TurboFLASH is a widely accepted viability imaging technique and a 3D viability strategy, incorporating respiratory gating, have been shown to detect small myocardial scars compared to 2D approaches. The purpose of this study was to assess a 3D PSIR TurboFLASH imaging technique for detecting left ventricular myocardial scar and compare it to a conventional 2D PSIR TurboFLASH. This study demonstrated the navigator-gated 3D PSIR sequence shows equivalent results for the assessment of myocardial scar, quantitatively and qualitatively compared to routine segmented 2D-PSIR techniques

14:30         2948.     Clinical Evaluation of Free-Breathing 3D Delayed Enhancement Imaging for Myocardial Viability Assessment: Comparison with Routine Breath-Hold 2D Imaging

Computer 7

Thanh D. Nguyen¹, Matthew D. Cham¹, Pascal Spincemaille¹, Martin R. Prince¹, Jonathan W. Weinsaft¹, Yi Wang¹

¹Weill Medical College of Cornell University, New York, New York, USA

The objective of this study was to prospectively compare a recently developed free-breathing navigator-gated 3D (3DNAV) delayed enhancement MRI (DE-MRI) with routine breath-hold (2DBH) DE-MRI in patients with confirmed myocardial infarction. 23 patients were imaged with both techniques at 1.5T. Compared to 2DBH imaging, 3DNAV imaging provided significantly better image quality in 33% less scan time. 2DBH and 3DNAV imaging identified 90 and 91 involved segments and 22 and 24 transmural segments, respectively. There were a strong correlation and narrow limits of agreement between the two techniques with respect to detected infarct volumes.

15:00         2949.     LV Infarct Size and Peri-Infarct Zone Measurements: A Comparison of High Resolution 3D and Conventional 2D Late Gadolinium Enhancement Imaging

Computer 7

Dana C. Peters¹, Evan A. Appelbaum¹, Reza Nezafat¹, Yuchi Han¹, Kraig V. Kissinger¹, Beth Goddu¹, Warren J. Manning¹

¹Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA

A high spatial resolution 3D late gadolinium enhancement sequence was used to image seven patients with prior myocardial infarction.  The results show a clearer picture of scar morphology compared to 2D images, demonstrating features such as islands of viability, subendocardial infarcts not visualized on the 2D images, and improved papillary muscle scar detection.   The scar volume by 3D correlated well with 2D measurement, but the peri-infarct zone was larger by 2D.  This 3D higher spatial resolution imaging may be a step towards correlating infarct morphology with arrhythmias.

13:30         2950.     Signal Intensity in Myocardial Scars Detected by Delayed-Enhancement MRI Differs in Subjects with and Without Previously Known Myocardial Infarction

Computer 8

Raquel Espregueira Themudo¹,², Lars Johansson¹,³, Charlotte Ebeling Barbier¹, Lars Lind¹, Håkan Ahlström¹, Tomas Bjerner¹

¹Uppsala University Hospital, Uppsala, Sweden; ²Hospital Geral Santo António, Porto, Portugal; ³AstraZeneca, Gothenburg, Sweden

This study comprised signal intensity analysis of myocardial scars in delayed-enhancement Magnetic Resonance Imaging aiming to investigate if there was any difference between clinically recognized myocardial infarctions and clinically unrecognized myocardial scars. There was a significant difference between the signal intensity ratio between these 2 groups, suggesting that it might represent a difference in the scar tissue composition.

14:00         2951.     Low Dose Dobutamine Adds Incremental Value to Delayed Enhancement Cardiac MR in the Prediction of Adverse Remodelling Following Acute Myocardial Infarction

Computer 8

Anne Elizabeth Scott¹, Scott Ian Semple¹, Thomas Redpath¹, Graham Hillis¹

¹Aberdeen University, Aberdeen, UK

The development of left ventricular dilatation in the months following acute myocardial infarction (AMI) is known as ‘adverse remodelling’ and confers a poor prognosis.  Adverse remodelling is measured as changes in left ventricular end diastolic volume (LVEDV).  We examined the relative utility of delayed enhancement (DE) and low dose dobutamine (LDD) CMR parameters, recorded 2 to 6 days post AMI, as predictors of changes in LVEDV six months later. LDD parameters added incremental value to DE parameters and were independently predictive of adverse remodelling.

14:30         2952.     Cardiac Phase-Resolved Acute Myocardial Infarct Imaging in Swines

Computer 8

Rohan Dharmakumar¹, Nirat Beohar¹, Jain Mangalathu Arumana¹, Zhouli Zhang¹, Debiao Li¹,²

¹Northwestern University, Chicago, Illinois, USA; ²Evanston, Illinois, USA

This work examines the feasibility of cardiac phase-resolved acute myocardial infarct imaging.  Experimental studies performed in animals show that cardiac SSFP cine imaging can be used to determine the presence of acute MI.

15:00         2953.     Delayed Enhancement of the Peri-Infarct Border Zone is Significantly Affected by Partial Volume Averaging: Insights from Ex Vivo Rat Heart Images at a Near-Cellular Resolution

Computer 8

Li-Yueh Hsu¹, Erik B. Schelbert¹, Stasia A. Anderson¹, Bibhu D. Mohanty¹, Syed M. Karim¹, Peter Kellman¹, Anthony H. Aletras¹, Andrew E. Arai¹

¹National Institutes of Health, Bethesda, USA

We hypothesized that the intermediate signal intensity in the peri-infarct border zone between normal and infarcted myocardium maybe explained by partial volume averaging. Using 3D ex vivo rat heart MRI at an isotropic voxel resolution equivalent to 3 cardiomyocytes, we quantified the volume of peri-infarction on the acquired isotropic 3D high resolution images and on post-hoc slab averaged low resolution images.

13:30         2954.     Detection of Recent Myocardial Infarction Using CINE SSFP Imaging

Computer 9

James William Goldfarb¹, Lenore Barhak¹, Jing Han¹

¹Saint Francis Hospital, Roslyn, USA

In this study, use of conventional CINE SSFP imaging for the detection of myocardial edema resulting from recent MI was investigated. The signal behavior of infarcted and viable myocardium as well as the LV bloodpool was investigated as a function of cardiac phase to determine the image parameters for optimal imaging of myocardial edema. In CINE SSFP images, the LV bloodpool and myocardial signal intensities vary normally with cardiac phase. Myocardial edema can be best detected at the end of systole when its contrast with adjacent myocardium is the greatest.

14:00         2955.     Fat/Water Separated Delayed Hyperenhanced (DHE) Myocardial Infarct Imaging

Computer 9

James William Goldfarb¹

¹Saint Francis Hospital, Roslyn, USA

A three-point DIXON acquisition and reconstruction was combined with an inversion recovery gradient-echo pulse sequence.  This allowed fat/water separation along with contrast-enhanced T1 sensitive delayed hyperenhanced myocardial infarct imaging.  The technique was demonstrated in phantom experiments and subjects with chronic myocardial infarctions. Areas of infarction were well defined as conventional hyperenhancement in water images.  Fatty deposition of myocardial infarction detected using this novel sequence was confirmed by precontrast opposed phase imaging.

14:30         2956.     T2-Component of Conventional Cine SSFP Sequences is Sufficient to Detect Myocardial Edema in Patients with Acute Reperfused Myocardial Infarction

Computer 9

Andreas Kumar¹, Rohan Dharmakumar², Jordin D. Green³, Jacqueline Flewitt¹, Matthias G. Friedrich¹

¹University of Calgary, Calgary, Canada; ²Northwestern University, Chicago, Illinois, USA; ³Siemens Canada, Calgary, Canada

T2 spin echo sequences are commonly used to detect edema in acute myocardial infarction. Here, we show that the inherent T2 weighting of cine SSFP sequences used for functional imaging of the heart may be sufficient to detect edema. This may abolish the need for a dedicated T2 spin echo sequence in the imaging protocol for acute myocardial infarction.

15:00         2957.     Improved Myocardial Viability Imaging with T2-Prepared Inversion Recovery (T2PREP-IR)

Computer 9

Chia-Ying Liu¹, Oliver Wieben¹, Jean H. Brittain², Scott Brian Reeder¹

¹University of Wisconsin-Madison, Madison, Wisconsin, USA; ²GE Healthcare, Madison, Wisconsin, USA

The clinical applications of delay-enhanced (DE) MRI using inversion recovery (IR) preparation are increasingly important for evaluation of myocardial viability. However, due to the similar T1 values of blood and infarcted tissue (MI), the contrast between the ventricular blood and subendocardial MI is often limited, adversely impacting the detection and evaluation of infarcted tissue. Exploiting differences between blood and myocardial T2, we propose a method that combines IR and T2 preparation into a single magnetization-prepared sequence (T2Prep-IR) to achieve T1 and T2 contrast within a single imaging acquisition to improve differentiation of enhancing subendocardial infarction and blood.

13:30         2958.     Free-Breathing Delayed Contrast-Enhanced Three-Dimensional Viability MR Imaging of the Myocardium at 3T: A Feasibility Study

Computer 10

Yasuo Amano¹, Morimasa Takayama², Yoshio Matsumura³, Yuriko Suzuki⁴, Shinichiro Kumita¹

¹Nippon Medical School, Tokyo, Japan; ²Sakakibara Memorial Hospital, Tokyo, Japan; ³Nippon Medical Schhol, Tokyo, Japan; ⁴Philips Medical Systems, Tokyo, Japan

Free-breathing delayed contrast-enhanced three-dimensional (3D) viability imaging of the myocardium at three-tesla (3T) magnetic resonance was compared with breath-hold two-dimensional (2D) viability imaging for assessments of CNR and extensions of damaged myocardium. A k-space weighted navigator and cardiac gating were used. This 3D imaging technique depicted 83.8 % of hyperenhancing myocardia with high CNR between hyperenhancing myocardium and blood and excellent agreement for transmural extension of the damaged myocardia (k = 0.875). Free-breathing delayed contrast-enhanced 3D viability imaging was feasible for the evaluation of the hyperenhancing myocardium at 3T.

14:00         2959.     Simulation of Artificial Delayed Hyperenhancement Resulting from Signal Modulation in the Phase Encoding Direction

Computer 10

Amol S. Pednekar¹

¹Philips Medical Systems, Bothell, Washington, USA

An artificial mid-spetal hyperenhancement often appears on the inversion recovery prepared interleaved segmented gradient recalled echo (IRISGRE) sequence with a low-high phase encoding order. In this simulation we studied the imaging artifacts resulting due to the signal modulation across the phase encode direction in the IRISGRE sequence. These hyperenhancement artifacts capable of leading to the spurious diagnosis of myocardial scarring, can be avoided by using liner phase encoding order.

14:30         2960.     T1 Pulse Sequence Optimization in a Diabetic Cohort

Computer 10

Warren Foltz¹, Kim Alexander Connelly¹,², Venkat Ramanan, Gideon Paul¹, Graham Wright¹, Alexander Dick¹

¹Sunnybrook Health Sciences Centre, Toronto, Canada; ²St Michael's Hospital, Toronto, Canada

Quantitative MRI measurements of left ventricular remodeling have the potential to facilitate earlier diagnosis and allow therapeutic monitoring of patients with diabetic cardiomyopathy. The Gd-DTPA partition coefficient or λ, defined as the tissue-to-blood ratio of extra-cellular volume fractions, should be valuable because changes in λ from control values of 0.3 reflect alterations in the extra-cellular volume, such as that seen in pathological ventricular remodeling.  We performed quantitative λ measurements within a diabetic cohort using a cardiac-gated but free-breathing single-point spiral T1prep strategy.  Mean λ appears to be elevated to 0.44 from control levels. The spiral methodology appears to provide reproducibility in global λ quantification which is on the order of 10%, which is the sensitivity target for monitoring diabetic remodeling.

15:00         2961.     Myocardial T_1ρ Mapping at 3T Using a Novel Spin-Locking Technique

Computer 10

Benjamin Edward Northrup¹,², Xiang He¹, Kyle Stephan McCommis¹, Jie Zheng¹

¹Washington University School of Medicine, St. Louis, USA; ²Dartmouth Medical School, Hanover / Lebanon, USA

A new spin-locking technique was used in conjunction with segmented gradient-recalled echo and TrueFISP acquisitions on a 3T MRI system to acquire cardiac T1-weighted images in a single (~20 second) breath-hold.  This facilitated the calculation of single-section myocardial T_1ρ maps with minimal intra-scan motion artifacts.  No significant difference between GRE and TrueFISP myocardial T_1ρ signal values was observed.  No difference in T_1ρ values among the three spin-locking frequencies was observed.  This study provided baseline myocardial T_1ρ mapping data in normal subjects, which will be useful for the evaluation of myocardial function with T_1ρ techniques in the future.

Safety:  Acoustic Noise

14:00         2962.     Experimental Reduction of Acoustic Noise Through Cancellation of Impulsive Forces

Computer 9

Xin Chen¹, Xingxian Shou¹, Jamal J. Derakhshan¹, Shmaryu M. Shvartsman,¹², Jeffrey L. Duerk¹,³, Robert W. Brown¹

¹Case Western Reserve University, Cleveland, Ohio, USA; ²Hitach Medical Systems, Twinsburg, Ohio, USA; ³University Hospitals, Cleveland, Ohio, USA

MRI acoustic noise is a long-standing problem exacerbated by higher field strengths and faster imaging.  We investigate the idea of using the impulsive forces produced by gradient ramping to cancel each other.  Guided by string simulations, we conduct experiments to test pulse sequences incorporating these cancellations.  As examples of appropriate timings, combinations of trapezoid or “quadratic” pulses or pairs of trapezoids are shown to cancel three frequencies and their harmonics.  All results are in good agreement with the simulations and Fourier theory.  A rich variety of possibilities in sequence design, including the TR freedom, may be optimized for noise control.

14:30         2963.     Analysis of Acoustic Noise Transfer Function in MRI: Multi-Center Trial

Computer 9

Takashi Hamaguchi¹, Tosiaki Miyati², Masaya Hirano³, Yasuhiro Fuziwara⁴, Hirohiko Kimura⁴, Hiroyasu Takeda⁵, Yasuo Takehara⁵, Kenro Nagashima⁶, Yuriko Suzuki⁶, Jousei Ueda²

¹Kanazawa University Hospital, Kanazawa, Japan; ²Kanazawa University, Kanazawa, Japan; ³GE Medical Systems, Hino, Japan; ⁴University of Fukui Hospital, Japan; ⁵Hamamatsu University School of Medicine,

We determined a gradient-pulse-to-acoustic-noise transfer function (GPAN-TF) at various MRI centers. We measured sound pressure levels in the frequency domain in six clinical super-conducting MRI systems, and calculated a GPAN-TF in each gradient coil. GPAN-TF at a high frequency range was larger than that at low frequency for all MR scanners. For high frequency, the 3.0-T MR scanner had a larger GPAN-TF than that of 1.5-T. MR scanner with a vacuum chamber reduced GPAN-TF at a lower frequency. GPAN-TF analysis enables to obtain more detailed information on acoustic noise properties independent of pulse sequences or imaging parameter in MR scanner.

15:00         2964.     Experimental Study of Active Acoustic Noise Control with MRI Compatible Headphones and Microphones in a 4T MRI Scanner

Computer 9

Jing-Huei Lee¹, Brent W. Rudd¹, Mingfeng Li¹, Jeffrey Osterhage¹, Teik C. Lim¹

¹University of Cincinnati, Cincinnati, USA

Typical speakers and microphones utilizing magnetic components are unable to be used in the vicinity of the MRI scanner.  In this study, we reproduced MRI noise in a sound quality chamber while measuring SPL and running a feed-forward control system targeting one of the dominant frequencies. The noise reduction performance of a high fidelity headphone/microphone containing magnetic components is compared with an MRI compatible combination utilizing piezoelectric speakers and an optical microphone.  In this report, the results from the sound quality chamber show that the MRI compatible system produces results that are comparable to that of the high fidelity system.

15:30         2965.     Sound Pressure Level Prediction of Arbitrary Sequences

Computer 9

Sebastian Schmitter¹, Lothar Rudi Schad²

¹German Cancer Research Center, Heidelberg, Germany; ²University of Heidelberg, Mannheim, Germany

During MR image acquisition huge sound pressure levels are generated, which can tamper the results of auditory fMRI experiments. A prediction of the generated acoustic noise and its spectrum is necessary in order to adapt auditory stimuli to the scanning sequence. In this work the linearity between gradient amplitude and sound pressure is verified in a wide range between 60 and 115dB. This linearity is exploited in a simulation program which predicts the SPL of an arbitrary sequence.

A loud and a silent sequence were exemplarily simulated, the results deviate only 1.8dB from the measured values.

Safety: Implants & Devices

13:30         2966.     An Evaluation of the Potential Extent of Catheter Heating During MR Imaging

Computer 10

Alastair Martin¹, Bryant Baek², Gabriel Acevedo-Bolton², Randall Higashida¹, John Comstock², David Saloner¹,²

¹University of California, San Francisco, California , USA; ²San Francisco VA Medical Center, San Francisco, California , USA

An obstacle to the incorporation of MR methods in endovascular procedures is the potential for focal heating near catheters and guidewires.  This study investigated the magnitude of heating near endovascular devices in a tissue mimicking phantom.  A fiber-optic temperature sensing system was used to measure temperature changes in an assortment of geometric conditions and with SAR levels up to 4W/kg.  Heating was found to be amplified near these devices and was a function of immersed device length, position within the bore, and SAR.  SAR limits are proposed as sufficient for safely imaging catheterized patients without concern for thermal injury.

14:00         2967.     MR Safety and Compatibility of Cardiac and Peripheral Stents at 7T

Computer 10

Ivan Emilov Dimitrov¹,², Aman Haider³, Emmanouil Brilakis², Subhash Banerjee³, Craig Malloy²,³

¹Philips Medical Systems, Cleveland, Ohio, USA; ²University of Texas Southwestern, Dallas, Texas, USA; ³Dallas VA Medical Center, Dallas, Texas, USA

We investigated the magnetic interactions (translational attraction, torque), RF heating, and artifact levels for five coronary and four peripheral stents (Express, Cypher, Ultra, Palmaz are made of stainless steel; Vision, Driver  -  cobalt chromium; Sentinol, Precise -  nitinol) at 7T. With the exception of Palmaz, all stents showed deflection less than 45 degrees. All stents exhibited no torque and insignificant RF heating (0.1 – 0.2 0C). Artifact levels were different for the different stents, all of them creating a void few times their geometrical sizes. All stents, with the exception of the large stainless steel Palmaz, are MR safe at 7T.

14:30         2968.     Evaluation of RF and Resistive Heating of Magnetically- Assisted Remote Control (MARC) Steering Coils in Endovascular Interventional MRI

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Fabio Settecase¹, Timothy P. L. Roberts², Walter Kucharczyk³, Steven Hetts¹, Mark Wilson¹, Ron Arenson¹

¹University of California San Francisco, San Francisco, California , USA; ²Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; ³University of Toronto, Toronto, Canada

Catheters can be steered in interventional MRI using magnetic moments induced by applying current to orthogonally arranged wire coils at a catheter tip.  Nonferromagnetic conducting wires, however, can cause significant radiofrequency (RF) heating in MRI. This study demonstrates, in a worst case scenario without convective blood flow, RF-induced temperature increases using a MARC-steered catheter are less than 1ºC after 15 min of real-time MRI. Physiologically significant resistive heating (greater than 4ºC) occurs only above 200 mA for 30 s in multiple coils. MARC steering may be an attractive alternative to catheter navigation with heating safety concerns arising only at higher currents using this prototype.

15:00         2969.     MR-Safety and Compatibility of Silver Based Wound Dressings at 7T

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Steffen Sammet¹, Zaid Chaudhry¹, William TC Yuh¹, Rebecca Coffey¹, Andrew Crockett¹, Sidney Miller¹, Michael Vincent Knopp¹

¹The Ohio State University, Columbus, USA

The purpose of this study was to determine whether silver based wound dressings are compatible with MRI imaging by investigating if ultra high field MRI and silver based dressings produce either increased body surface temperature and/or caused distortions in the resulting MR image. All tested silver containing wound dressings are both safe and compatible with MRI at 7T.

RF Receive Coils

13:30         2970.     Reduction of SNR Losses Due to RF Coil Coupling Via Coil Current Sensing

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Randy Duensing¹

¹Invivo Corporation, Gainesville, Florida, USA

This method employs a new paradigm in multi-channel RF coils in which coupling (in moderate amounts) is not detrimental as long as it is measurable, thus permitting algebraic inversion. Two preamplifiers are utilized in each loop, one preamplifier with the impedance mismatched used to provide inductive decoupling, but the other matched to produce minimal impact on the loop impedance.  This second non-damping preamplifier measures the residual current in the loop and therefore a model of voltage coupled in other nearby coils.  Utilization of this additional signal improves the SNR over standard methods when the coupling is moderate.

14:00         2971.     Transmission Line Effects on the Noise Correlation Matrix for Multiple RF Coils

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Ryan Brown¹,², Yi Wang¹,²

¹Weill Medical College of Cornell University, New York, USA; ²Weill Graduate School of Medical Sciences of Cornell University, New York, USA

The original noise correlation formula derived by Redpath showed correlation depends on the real part of the impedance matrix.  In this work, we introduce a more generalized formula to include effects from transmission lines and preamplifier impedance mismatch.  This formula is used to calculate correlation between two-channel circuits connected to preamplifiers using several transmission line lengths.  The calculated correlation matches well with that measured on the MR scanner and suggests transmission line length can be utilized as an additional degree of freedom for coil decoupling, and can be adjusted to achieve zero noise correlation.

14:30         2972.     An Eigenvalue/eigenvector Analysis of Decoupling Methods and Its Application at 7T MR Imaging

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Zhentian Xie¹, Xiaoliang Zhang¹,²

¹UC San Francisco, San Francisco, California , USA; ²UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco & Berkeley, California , USA

this work, we report an eigenvalue/eigenvector analysis method for designing non-overlapped coil arrays and one of its immediate applications as a novel decoupling method. The proposed microstrip array coil for 7T MRI, consisted of 2 microstrip resonators and one microstrip decoupling line, was built on a Teflon cylinder. Bench test and preliminary imaging results show that the proposed design provides a robust approach to design of parallel imaging arrays at ultrahigh fields.

15:00         2973.     An 8-Channel Microstrip Array Coil for Mouse Parallel MR Imaging at 7T by Using Magnetic Wall Decoupling Technique

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Zhentian Xie¹, Xiaoliang Zhang¹,²

¹UC San Francisco, San Francisco, California , USA; ²UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco & Berkeley, California , USA