Traditional Posters : Cardiovascular Imaging
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Cardiovascular Image Processing

 
Tuesday May 10th
Exhibition Hall  13:30 - 15:30

1171.   Observation of cardiovascular dynamics by field recording with an NMR probe  
Klaas Paul Pruessmann1, Benjamin Emanuel Dietrich1, and Christoph Barmet1
1Institute for Biomedical Engineering, University and ETH Zürich, Zurich, Zurich, Switzerland

 
In this work, field measurements with an NMR field probe are explored as a means of observing cardiovascular dynamics. Using an optimized probe and custom-built transmit and receive hardware, field measurements were performed at different position on a volunteer’s chest. The measurements were found to reveal detailed and highly periodic field dynamics at the cardiac frequency, indicating that these reflect actual dynamics of heart motion and blood flow.

 
1172.   Automatic Segmentation of Short-Axis Cardiac MRI Using a Biventricular Deformable Model with an Explicit Thickness Prior 
Paul A. Yushkevich1, Hui Sun1, Federico M. Sukno2, Catalina Tobon-Gomez2, Hongzhi Wang1, and Alejandro F. Frangi2
1PICSL, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2CISTIB, Universitat Pompeu Fabra, CIBER-BBN, Barcelona, Spain

 
This new approach overcomes some of the challenges in automatic cardiac MRI segmentation of by modeling the myocardium using a deformable model that explicitly describes the skeleton of the myocardium and its thickness. This geometrical model is coupled with an appearance model and statistical shape prior learned from training data. The proposed approach achieves high accuracy compared to manual segmentation on end-diastole MR images of patients with common pathologies.

 
1173.   Myocardial T1 Mapping with Synthetic Image Estimation based Motion Correction 
Hui Xue1, Saurabh Shah2, Andreas Greiser3, Christoph Guetter1, Christophe Chefdhotel1, Marie-Pierre Jolly1, Sven Zuehlsdorff2, Jens Guehring1, and Peter Kellman4
1Imaging and Visualization, Siemens Corporate Research, Princeton, NJ, United States, 2CMR Research and Development, Siemens Medical Solutions USA, Inc., Chicago, IL, United States,3Imaging & IT Division, Siemens AG, Healthcare Sector, Erlangen, Germany, 4National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States

 
The state-of-art technique for cardiac T1 mapping is the modified Look-Locker Inversion Recovery (MOLLI) which acquires multiple images across several heart-beats. Its clinical applicability is often limited by frequent myocardial motion because of imperfect breath-hold or varying R-R interval. A fully automated motion correction directly utilizing MOLLI images is highly challenging due to significantly varying image contrast. We therefore propose a novel registration algorithm based on estimating motion-free synthetic images presenting similar contrast to original MOLLI data by solving a variational energy minimization problem. The validation was performed in vivo on a large cohort of patient datasets.

 
1174.   Cardiac Diffusion Tensor Imaging Registration 
Carla S Gil1, Niall Colgan1, A J Bakermans2, B J van Nierop2, G J Strijkers2, H C van Assen3, and Kathleen M Curran1
1School of Medicine and Medical Sciences, University College of Dublin, Dublin, Belfield, Dublin 16, Ireland, 2Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands, 3Biomedical Image Analysis, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands

 
The purpose of this paper is to register ex-vivo cardiac diffusion tensor images using affine transformations and the preservation of the principal direction reorientation strategy. We have successfully registered cardiac DTI and compared five different similarity measures: relative anisotropy difference, modulus difference, tensor difference, normalized tensor difference and principal direction difference. Results indicate that the principal direction difference is superior to the other similarity measures, followed by the normalized tensor difference and tensor difference. For cardiac DTI registration, measures sensitive to the full tensor perform better than scalar derived measures.

 
1175.   Accuracy of Automatic Contour Detection for Quantification of Left Ventricular Volumes, Mass and Ejection Fraction 
Gilion Hautvast1, Carol Salton2, Michael Chuang2,3, Marcel Breeuwer1,4, Christopher O'Donnell3,5, and Warren Manning2
1Philips Healthcare, Best, Netherlands, 2Beth Israel Deaconess Medical Center, Boston, MA, United States, 3National Heart, Lung and Blood Institute, Framingham, MA, United States,4Eindhoven University of Technology, Eindhoven, Netherlands, 5Massachusetts General Hospital, Boston, MA, United States

 
In this work we examine cine CMR data derived from a large, community-based cohort to determine: 1) the contribution of the basal LV slice(s) at ED to LV volumes and EF and 2) the effect of manual correction of automatically-detected LV contours on global LV functional parameters. Our results show that automatic myocardial contour detection for determination of LV volumes and EF is feasible and accurate in a large, population-based sample of adults. After inclusion of basal slice data, further manual corrections to the automatically-detected contours have minimal effect on the final outcome of global functional parameters.

 
1176.   Dark Regions of No-Reflow on LGE-MRI Result in Permanent Scar Post Atrial Fibrillation Ablation 
Christopher J McGann1, Eugene G Kholmovski1, Joshua J.E. Blauer1, Sathya Vijayakumar1, Thomas S Haslam1, Joshua E Cates1, Nazem W Akoum1, Edward V.R. Dibella1, Nathan S Burgon1, Alton J Alexander1, Marcelinus Prastawa1, Dennis Parker1, Rob MacLeod1, and Nassir F Marrouche1
1CARMA Center, Salt Lake City, Utah, United States

 
When LGE imaging is performed immediately post-ablation, heterogeneous injury is seen with both bright (hyperenhancing) and dark (non-enhancing) lesions. The relationship between the acute injuries seen on LGE and late scar formation has not been well studied. Ten patients presenting for AF ablation underwent 3D LGE MRI immediately post ablation (IPA) and three months post-ablation (3moPA) on a 3T scanner. The IPA injuries were evaluated and categorized as either hyperenhancing (HE) or non-enhancing (NE) lesions and compared to scar 3moPA. The NE lesions demonstrate 'no-reflow' characteristics and may improve prediction of final scar at 3 months.

 
1177.   Preserved Ejection Fraction in the Presence of Reduced LV Wall Strain in Hypertension: A Geometric Explanation Validated by MRI 
Wei Zha1, Steven Lloyd2, Himanshu Gupta2, Louis Dell’Italia2, and Thomas S. Denney1
1ECE, Auburn University, Auburn, AL, United States, 2Medicine and Radiology, University of Alabama at Birmingham, Birmingham, AL, United States

 
This abstract derives a relationship between ejection fraction as a function of wall thickening, radius thickness ratio, longitudinal shortening and circumferential shortening. Validated using cine and tagged MRI of 458 human subjects, the derived expression suggests that in hypertension, the preserved ejection fraction in the presence of reduced circumferential shortening can be explained by the geometric effects of concentric remodeling.

 
1178.   Improved Cardiac MRI of Preterm Infants using Retrospective Cardiac and Respiratory Gating 
Anthony N Price1, Shaihan J Malik1, Kathryn M Broadhouse1, Francesco Padormo1, Giuliana Durighel1, David J Cox1, A David Edwards1, Alan M Groves1, and Jo V Hajnal1
1Robert Steiner MRI Unit, Imaging Sciences Department, MRC Clinical Sciences Centre, Hammersmith Hospital, Imperial College London, London, United Kingdom

 
Cardiac MRI has the scope to significantly advance understanding of circulatory function in newborn infants. Previously, image quality in these infants has been degraded by respiratory and whole body motion since infants are not sedated or anesthetised during scanning. In this study imaging was performed with monitoring of respiratory and whole body motion using a pressure sensor placed on the abdominal wall. Real time SSFP imaging was utilised to demonstrate that abdominal pressure sensing accurately predicts diaphragmatic position. Rejection and binning of k-space data according to whole body motion and respiratory phase produced significant improvements in cine SSFP image quality.

 
1179.   Segmentation of Carotid Plaque using Multi-Contrast 3D Gradient Echo MR Imaging 
Wenbo Liu1,2, Niranjan Balu2, Xihai Zhao1, Huijun Chen2, Chun Yuan1,2, Huilin Zhao3, Jianrong Xu3, Guangzhi Wang1, and William S. Kerwin2
1Biomedical Engineering & Center for Biomedical Imaging Research, School of Medicine, Tsinghua University, Beijing, China, People's Republic of, 2Radiology, University of Washington, Seattle, WA, United States, 3Radiology, Shanghai Jiao Tong University, Shanghai, China, People's Republic of

 
To evaluate the use of 3D gradient echo imaging techniques to identify plaque components, we sought to compare performance of an automatic segmentation algorithm based on Morphology-Enhanced Probabilistic Plaque Segmentation (MEPPS) using traditional 2D spin echo images versus 3D gradient echo images. The results show in principle a protocol based on 3D gradient echo contrast weightings provides sufficient information to quantitatively characterize calcification, necrotic core, and loose matrix in carotid atherosclerotic plaque. The advantage of this approach is especially well represented by the 3D visualization results. The isotropic segmentation results permit visualization of plaque structure in arbitrarily reformatted cuts.

 
1180.   Free-breathing Technique for Myocardial T2* Measurement with GRE multi-echoes Pulse Sequence 
Suwit Saekho1,2, Uten Yarach1, Petai Buttakote1, Siriphan Luxsakhum1, Arintaya Phrommintikul3, and Nipon Chattipakorn4
1Radiological Technology, Chiang Mai University, Muang, Chiang mai, Thailand, 2Biomedical Engineering Center, Chiang Mai University, Muang, Chiang Mai University, Thailand, 3Internal Medicine, Chiang Mai University, Muang, Chiang Mai, Thailand, 4Cardiac Electrophysiology Research and Training Center, Chiang Mai University, Muang, Chiang Mai, Thailand

 
Accuracy, reproducibility and selected curve fitting model for the T2* measurement depend on SNR and resolution of MR images. Currently, single breath-hold technique has been used in most centers. The limitation of this technique is that acquisition time is constrained by the breath-holding capability in each individual resulting in limited SNR and resolution on images. We propose free-breathing technique to assess myocardial T2* employing a navigator pre-pulse to reduce motion artifact. This technique improved the resolution and SNR by approximately 40% resulting in better inter-study and intra-observer reproducibility, as well as less dependent to the curve fitting algorithms.

 
1181.   Optimal Image Combination with Minimal Total Deformation (MTD) Constrain To Improve Signal-Noise-Ratio (SNR) For Free-Breathing Cardiac Magnetic Resonance Imaging 
Hui Xue1, Ding Yu2, Saurabh Shah3, Christoph Guetter1, Marie-Pierre Jolly1, Orlando P. Simonetti2, Peter Kellman4, and Jens Guehring1
1Imaging and Visualization, Siemens Corporate Research, Princeton, NJ, United States, 2The Ohio State University, Columbus, Ohio, United States, 3CMR Research and Development, Siemens Medical Solutions USA, Inc., Chicago, IL, United States, 4National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States

 
Recent development in cardiac MR shows that improved SNR can be achieved by averaging the motion-corrected free-breathing images using non-rigid image registration. To motion correction induced artifacts, previous studies heuristically exclude some frames from final averaging. However, non-rigid image registration can lead to variant accuracy for different frames and different regions within a frame. We therefore propose a novel image combination algorithm, computing optimal weights for image combination by minimizing the total amount of deformation brought into the averaging. Compared to uniform averaging, our approach achieves good noise suppression and provides better tolerance to artifacts possibly introduced by motion correction.

 
1182.   Calculation of Mechanical Properties of the Inter-luminal Septum in DeBakey Type III Aortic Dissection from the Behavior of P-Waves Detected by cine MRI : Application of Seismic Technology onto Medical Image Data 
Pietro Valsecchi1, Christof Karmonik2,3, Jean Bismuth2, Mark G Davies2, Dipan J Shah2, Bill E Kline1, and Alan B Lumsden2
1ExxonMobil Upstream Research Company, Houston, TX, United States, 2The Methodist DeBakey Heart & Vascular Center, Houston, TX, United States, 3The Methodist Hospital Neurological Institute, Houston, TX, United States

 
High post-treatment mortality rates in DeBakey type III aortic dissections (AD) (20% in 3 years after hospital discharge) necessitates a better understanding of biomechanical properties of true (TL) and false lumen (FL) wall for the development of effective treatment. In an effort to create synergy between know-how in the energy industry and the medical community, we took advantage of established seismology techniques to estimate stiffness of the AD intra-luminal septum (IS) using the wall pressure wave. From this, Young's modulus of the IS was found to be approximately a factor 50 lower compared to literature values for healthy aortic wall.

 
1183.   Clinical T1 mapping in the heart - improved T1 map image quality by automated motion correction for Modified Look-Locker Inversion-recovery (MOLLI) 
Martin Ugander1, Hui Xue2, Jens Guehring3, Saurabh Shah4, Li-Yueh Hsu1, Andrew E Arai1, and Peter Kellman1
1National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States, 2Siemens Corporate Research, Princeton, NJ, United States, 3Siemens AG Healthcare Sector, Erlangen, Germany, 4Siemens Medical Solutions, Chicago, IL, United States

 
T1 mapping is emerging as a tool for quantitative assessment of myocardial disease. Quantitative T1 mapping can be undertaken using a Modified Look-Locker Inversion-recovery (MOLLI) sequence. We developed a fully automated motion-correction algorithm for MOLLI images. In 649 paired image comparisons from 178 patients, automated T1 map image quality following motion correction was assessed by a physician as unchanged in 91.8% of cases, improved in 7.6% of cases and worsened in 0.6% of cases. Automated motion correction in MOLLI imaging improves the image quality of both pre-contrast and post-contrast T1 maps of the heart in clinical patients.

 
1184.   Phase Unwrapping of PCMRI data 
Johann Baptist Drexl1, Ola Friman2, Anja Hennemuth2, Jelena Bock3, Michael Markl3, and Horst Karl Hahn1
1Fraunhofer MEVIS, Bremen, Bremen, Germany, 2Fraunhofer MEVIS, 3Department of Radiology, Medical Physics, University Hospital Freiburg, Germany

 
In this work, we evaluate Jenkinson's PRELUDE phase unwrapping method on phase contrast magnetic resonance imaging flow data of the human aorta. For the evaluation, we used aquired data from a volunteer as well as a simple digital phantom. We set up an image processing pipeline employing PRELUDE, and finally evaluate the performance of the method qualitatively and quantitatively using the misclassification rate and execution speed as metrics.

 
1185.   Noise Reduction in Real-Time Phase Velocity Images via the Karhunen-Loeve Transform 
Samuel Ting1, Yu Ding2, Yiu-Cho Chung3, and Orlando P. Simonetti1,2
1Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States, 2Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, United States, 3Siemens Medical Systems, Columbus, OH, United States

 
Real-time cardiac cine images acquired in settings where minimal acquisition time or patient conditions eliminate the possibility of breathhold or triggering techniques contain high levels of noise. We apply the Karhunev-Loeve Transform to real-time cine images for peak velocity measurement to reduce noise and compare our results to those obtained using spatial four- and eight- neighbor averaging. Filtering via the Karhunen-Loeve Transform successfully reduces signal noise while leading to a smaller affect on the peak velocity measurement compared to that of spatial averaging.

 
1186.   Characterization of Carotid Plaque in Three-Dimensional Ultrasound by Registration with Multicontrast MRI 
Bernard Chiu1, Vijay Shamdasani2, Robert Entrekin2, Chun Yuan1, and William S Kerwin1
1Radiology, University of Washington, Seattle, WA, United States, 2Ultrasound Investigations, Philips Healthcare, Bothell, WA, United States

 
Due to the cost effectiveness of US, it is beneficial to establish a screening strategy in which US is used to identify subjects suspicious of having vulnerable plaques, who are then further studied using MRI. To evaluate the viability of such screening strategy, it is crucial to establish to what extent US can predict subsequent MRI findings. To make this assessment possible, we developed a MR-US registration technique that establishes the spatial correspondence of different plaque components. Our registration method has an average error below 1mm. Also, we found a good correspondence between hyperechoic structures and calcifications in US images.

 
1187.   Comparison of the region-based and pixel-wise methods for cardiac T2* analysis in 50 transfusion-dependent Thai Thalassemia patients 
Pairash Saiviroonporn1, Vip Viprakasit2, Thananya Boonyasirinant3, John C Wood4, and Rungroj Krittayaphong3
1Radiology Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, 2Haematology/Oncology Division, Department of Pediatrics and Thalassemia Center, Faculty of Medicine Siriraj Hospital, Mahidol University, 3Division of Cardiology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, 4Divisions of Cardiology, Department of Pediatrics, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, United States

 
The study compared the observer variability of the conventional Region-Based (RB) to the typical and proposed Pixel-Wise (PW) methods for cardiac T2* analysis in thalassemia patients. Fifty thalassemia major patients were enrolled for the study. Short axis bright- and black-blood sequences were acquired and analyzed using the RB and PW methods. Regions were defined using the whole interventricular septum (WS) or partial septum (PS). The proposed Pixel-Wise method using median of T2* values calculated from PS region provided lower intra- and inter-observer variability as compared to the conventional Region-Based or typical Pixel-Wise methods on both scanning techniques.

 
1188.   Cardiac image segmentation using Level Sets with Preserved Topology 
Cristobal Arrieta1,2, Sergio Uribe2,3, Vicente Parot1,2, Pablo Irarrazaval1,2, Carlos Sing-Long2, and Cristian Tejos1,2
1Department of Electrical Engineering, Pontificia Universidad Catolica de Chile, Santiago, RM, Chile, 2Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, RM, Chile,3Department of Radiology, Pontificia Universidad Catolica de Chile, Santiago, RM, Chile

 
Cardiac performance is typically evaluated from left ventricle volume estimations obtained by segmenting cardiac MRI data. This segmentation is usually done by a tedious manual process, that shows low reproducibility. Different authors have proposed the use of Level-Sets to automate this process. Due to the presence of multiple objects in the image, Level-Sets normally require shape constrains that are built from a training procedures. Training-based segmentations tend to fail with severely abnormal anatomies. We propose the use of Level-Sets with Preserved Topology. Compared to manual segmentations we achieved equally accurate and more reproducible segmentations without training, even in abnormal patients.

 
1189.   Inter-Site Validation of the Pixel-Wise Method for Cardiac T2* Analysis in 50 Transfusion-Dependent Thai Thalassemia Patients 
Pairash Saiviroonporn1, Vip Viprakasit2, Thananya Boonyasirinant3, Archrob Khuhapinant4, John C Wood5, and Rungroj Krittayaphong3
1Radiology Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, 2Haematology/Oncology Division, Department of Pediatrics and Thalassemia Center, Faculty of Medicine Siriraj Hospital, Mahidol University, 3Division of Cardiology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, 4Haematology/Oncology Division, Department of Internal Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, 5Divisions of Cardiology, Department of Pediatrics, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, United States

 
This study investigated inter-site observer variability of the Pixel-Wise (PW) method for cardiac T2* analysis in thalassemia patients using the mono-exponential with constant fitting (offset) model as well as to compare the offset model to the mono-exponential with median report (MPS). The inter-site variability of the offset model on the PW method provided acceptable CV on both scanning technique and was comparable to the conventional method. When comparing the offset to MPS method, the variability was also comparable to previous report for the black-blood technique but substantially higher for the bright-blood technique due to the discrepancy at low T2* range.

Traditional Posters : Cardiovascular Imaging
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Flow Quantification & Vessel Function

 
Wednesday May 11th
Exhibition Hall  13:30 - 15:30

1190.   Quantitative Assessment of Blood Flow with 4D Phase-Contrast MRI and Autocalibrating Parallel Imaging Compressed Sensing 
Albert Hsiao1, Michael Lustig2, Marcus T Alley1, Mark Murphy2, and Shreyas S Vasanawala1,3
1Radiology, Stanford University, Stanford, CA, United States, 2Electrical Engineering and Computer Science, University of California, Berkeley, CA, United States, 3Radiology, Lucile Packard Childrens Hospital, Stanford, CA, United States

 
We demonstrate the combined use of parallel imaging, Poisson-disc k-space sampling and compressed sensing reconstruction in 4D phase-contrast MRI. We show that flow measurements at the aortic and pulmonary valves are essentially identical with compressed sensing (L1-SPIRiT) and without (ARC), while markedly improving image quality and noise. We further show that flow measurements at the aortic and pulmonary valves correlate well with conventional 2D phase-contrast and calculated cardiac outputs from cine SSFP imaging. These results favor the use of the compressed-sensing, when available, to maximize image quality while preserving the quantitative accuracy of 4D phase-contrast technique.

 
1191.   4D Aortic pressure difference mapping: an approach for the detection of pressure wave changes associated with atherosclerosis? 
Jelena Bock1, Ramona Lorenz1, Andreas Harloff2, and Michael Markl1
1Radiology, Medical Physics, University Medical Center, Freiburg, Germany, 2Neurology, University Medical Center, Freiburg, Germany

 
In this study we present initial results regarding the detection of pressure wave changes associated with atherosclerosis by applying 4D aortic pressure difference mapping. This approach was tested in patients with aortic high risk plaques versus healthy young volunteers. Patients’ data demonstrated similar peak pressure differences but showed altered waveform dynamics which reflect the expected increased aortic stiffness and resulted in earlier diastolic inversion of pressure waves.

 
1192.   Comparison of Accelerated Velocity Encoded MRI with SENSE and kt-BLAST in a Beating Heart Phantom 
Anja Lutz1, Fabian Sauter1, Axel Bornstedt1, Patrick Etyngier2, Robert Manzke3, Wolfgang Rottbauer1, G Ulrich Nienhaus4, and Volker Rasche1
1University Hospital of Ulm, Ulm, BW, Germany, 2Medisys Research Lab, Philips Healthcare, Sureness, France, 3Philips Research NA, Briarcliff Manor, United States, 4Karlsruhe Institute of Technology, Karlsruhe, Germany

 
Accurate quantification of myocardial motion requires high spatial and temporal resolution velocity-encoded MRI. Acceleration of the data acquisition appears mandatory for enabling three-dimensional coverage of the whole heart. It is the objective of this study to compare the impact of acquisition acceleration by means of SENSE and kt-BLAST on the velocity-time curves. The comparison is performed in a beating heart phantom ensuring highly reproducible motion pattern. The results indicate a superior performance of SENSE for preservation of the motion curves compared to kt-BLAST.

 
1193.   Image based Correction of Phasewraps in 4D PC-MRI Data Using Fast Reference Scans 
Daniel Stucht1, Michael Markl2, Rocco Gasteiger3, and Oliver Speck1
1Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Germany, 2Dept. of Diagnostic Radiology, Medical Physics, University Hospital, Freiburg, Germany, 3Institute of Simulation and Graphics, Otto-von-Guericke University, Magdeburg, Germany

 
4D PC-MRI is used to measure four dimensional blood flow and characterize vascular hemodynamics. If the actual flow velocities exceed the venc parameter which specifies the velocity sensitivity, velocity phase wraps will occur. A simple method to correct these phasewraps is to aquire the data twice. Once with the lower venc, then with a higher venc to correct the phase wraps in the first dataset. The aim of this study is, to systematically analyze in phantom scans to what extent a reduction of the additional scan time for the reference scan can be achieved by reducing its spatial and temporal resolution.

 
1194.   Measurement of morphological and functional changes of the vessel wall during the progression of atherosclerosis in the ApoE-/- mouse model by MR-Microscopy at 17.6T 
Alexander Gotschy1,2, Volker Herold2, Gunthard Lykowsky2, Elisabeth Bauer1, Eberhard Rommel2, Peter M Jakob2, and Wolfgang Rudolf Bauer1
1Department of Internal Medicine I, University Hospital Wuerzburg, Julius-Maximilians-University, Wuerzburg, Germany, 2Department of Experimental Physics 5, Julius-Maximilians-University, Wuerzburg, Germany

 
In this study we measured the functional and morphological changes that occur during the formation and progression of atherosclerotic lesions in the abdominal aorta of ApoE-/- mice by the use of MR-Microscopy at 17.6T. The morphological changes were quantified by determining the mean arterial wall thickness. As functional parameter we assessed the local pulse wave velocity (PWV) which is an indicator for the arterial stiffness. Thereby we found, that the local PWV increases clearly before morphological changes are detectable, which makes the local PWV a very sensitive parameter for the examination of early stages of atherosclerosis.

 
1195.   Quantification of Ductus Arteriosus Shunt Volume in Preterm Infants using Phase Contrast CMR 
Kathryn Mary Broadhouse1, Anthony N Price1, Giuliana Durighel1, David J Cox1, A D Edwards1, J V Hajnal1, and Alan M Groves1
1Robert Steiner Unit, Imaging Sciences Department, MRC Clinical Sciences Centre, Hammersmith Hospital, Imperial College London, London, United Kingdom

 
Persistent Patent Ductus Arteriosus (PDA) remains a common clinical presentation in preterm infants. Phase contrast MRI was used to quantify volume of ductal shunt and define the impact of PDA shunt on true systemic perfusion. Volume of left ventricular output and systemic blood flow (in the superior vena cava and descending aorta) was quantified in preterm infants. In infants with proven ductal closure, measured volume of systemic flow was closely correlated to left ventricular output. In infants with a PDA the volume of ductal shunt was variable, but accounted for up to 60% of left ventricular output. It was also demonstrated that a significant PDA determined by classical measures may not always cause systemic hypo-perfusion.

 
1196.   Evaluation of nth Order Polynomial Phase Correction in Reprojected Line Scan Phase Contrast MRA 
Erik J Offerman1, Ioannis Koktzoglou1,2, Christopher Glielmi3, and Robert R Edelman1,4
1Radiology, Northshore University HealthSystem, Evanston, IL, United States, 2Radiology, The University of Chicago, Chicago, IL, United States, 3Siemens Healthcare, Chicago, IL, United States, 4Radiology, Northwestern University, Chicago, IL, United States

 
Reprojected Line Scan Phase Contrast (rLSPC) MRA is a technique that produces a coronal cine of blood flow velocity over a large field of view. The quality of the cine is diminished by phase errors; a phase correction (PC) technique is evaluated in vivo. The technique subtracts background phase from each line in the cine using a polynomial fit of defined order. Polynomial PC was performed on rLSPC at orders 1 to 8. Orders were compared to themselves and to no PC using measurements of flow velocity and standard deviation of the background. Improvement of velocity quantification and image quality was seen with polynomial PC; marginal improvement was seen at high orders.

 
1197.   PC Velocity Encoding: Temporal Characteristics of 1-sided, 2-sided non-SVE, and 2-sided SVE 
Jacob Bender1,2, Yu Ding2, Yiu-Cho Chung3, Subha Ramen4, and Orlando Simonetti2,5
1Biomedical Engineering, The Ohio State University, Columbus, OH, United States, 2Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, United States,3Siemens Medical Systems, Inc, Malvern, PA, United States, 4The Ohio State University, Dorothy M. Davis Heart & Lung Research Institute, Columbus, OH, United States, 5The Ohio State University, Biomedical Engineering, Columbus, OH, United States

 
Poor temporal resolution is an on going problem for MRI-PC peak velocity quantification. The temporal characteristic of 1-sided velocity encoding, 2-sided velocity encoding without SVE, and 2-sided velocity encoding with SVE are explored.

 
1198.   Comparison of Pulse Wave Velocity Measurements from 2D PC Slices and Radially Undersampled 4D PC MR 
Andrew Louis Wentland1,2, Oliver Wieben1, Kevin M Johnson1, Chris J Francois2, Thomas M Grist2, and Alex Frydrychowicz2
1Medical Physics, University of Wisconsin School of Medicine & Public Health, Madison, WI, United States, 2Radiology, University of Wisconsin School of Medicine & Public Health, Madison, WI, United States

 
Pulse wave velocity (PWV) is a useful biomarker of vascular stiffness. We investigated the use of a radially undersampled 4D PC MRI acquisition with high temporal resolution for computing PWV; PWV was computed by analyzing flow waveforms in 7-8 planes along the thoracic aorta in five volunteers. These PWV measurements were compared to PWV measurements derived from four 2D PC slices. PWV was computed with four methods: time-to-upstroke, time-to-peak (TTP), time-to-foot (TTF), and cross-correlation (XCorr). 2D TTP, TTF, and XCorr and 4D TTF produced non-physiologic results. 4D results were less variable than the 2D results.

 
1199.   Accuracy of the cylinder approximation for susceptometric measurement of intravascular oxygen saturation versus numerical calculation of induced field 
Cheng Li1, Michael C. Langham1, Jeremey F. Magland1, Charles L. Epstein1,2, Jue Wu1, James C. Gee1, and Felix W. Wehrli1
1Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Department of Mathematics, University of Pennsylvania, Philadelphia, PA, United States

 
Quantification of blood oxygen saturation level in large vessels with MR susceptometry-based oximetry has previously been used for quantifying peripheral vascular reactivity and global cerebral metabolic rate of oxygen utilization. A key assumption underlying this method is modeling large vessels as long paramagnetic cylinders. Here, we evaluate the “long cylinder” approximation by numerically computing the induced magnetic field of 3D segmented femoral vein and superior sagittal sinus. Analytical and numerical solutions were found to be in good agreement for tilt angles less than 40o despite vessel tapering and curvature.

 
1200.   Distensibility measurements along carotid atherosclerotic plaques: how can we improve the mechanical modeling of atherosclerosis? 
Gador Canton1, Daniel Scott Hippe1, Jie Sun1, Dongxiang Xu1, Hunter R Underhill1, William Sean Kerwin1, Dalin Tang2, and Chun Yuan1
1Radiology, University of Washington, Seattle, Washington, United States, 2Mathematical Sciences Department, Worcester Polytechnic Institute, Worcester, MA, United States

 
Biomechanical modeling of atherosclerotic plaques depends on accurate estimation of local mechanical properties along the diseased vessel wall. We sought to characterize wall distensibility along atherosclerotic carotid bifurcations and the effect of plaque burden and composition on this mechanical property. CINE MRI was used to measure wall distensibility and multi-contrast MRI was used to characterize vessel wall morphology and composition. Distensibility was found to be similar along diseased bifurcations. Plaque burden and composition were not found to contribute to wall distensibility. Thus, vascular stiffening in the carotid arteries of the analyzed cohort appears to be systemic and less influenced by local plaque features.

 
1201.   Improving 3D MR Velocity-Vector Field Mapping by Divergence-Free Image Reconstruction 
Julia Busch1,2, Daniel Giese1,3, Lukas Wissmann1, and Sebastian Kozerke1,3
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 2Ruprecht-Karls University Heidelberg, Heidelberg, Germany, 3Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom

 
The accuracy of velocity data derived from phase-contrast measurements is often compromised by partial volume effects and system imperfections. Although correction algorithms exist which aim to correct for noise and eddy-current related phase offsets residual phase errors remain. The present work introduces divergence-free image reconstruction for 3D phase-contrast vector field mapping based on a synergistic combination of normalized convolution and divergence-free radial basis functions. Using computer simulations and in-vivo data it is demonstrated that vector field divergence arising from measurement imperfections can be significantly reduced resulting in improved vector field representations.

 
1202.   Loss of hemodynamic information in intracranial aneurysms: phase contrast MRI in a real-size phantom at different spatial resolutions 
Pim van Ooij1,2, Annetje Guédon1,2, Joppe Schneiders1, Marcel C. M. Rutten3, Henk Marquering1,2, Charles B Majoie1, Ed vanBavel2, and Aart J Nederveen1
1Radiology, Academic Medical Center, Amsterdam, Netherlands, 2Biomedical Engineering & Physics, Academic Medical Center, Amsterdam, Netherlands, 3Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands

 
In this study 3D phase contrast MRI measurements at different spatial resolutions in a real-size intracranial aneurysm phantom are performed to study the loss of flow information when performing PC-MRI at low resolutions. It is observed that flow properties such as vortices can be measured at low resolutions. Voxel-by-voxel differences between high and interpolated low resolutions, however, increase when decreasing resolution. Furthermore, when velocity derivatives at the phantom wall, needed for wall shear stress estimations, are calculated, small as well as large differences are found. This can result in unreliable wall shear stress estimations.

 
1203.   Reprojected Line Scan Phase Contrast MRA of Peripheral Arterial Disease 
Robert R. Edelman1,2, Erik Offerman3, Christopher Glielmi4, Eugene Dunkle3, Navyash Gupta3, and Ioannis Koktzoglou5,6
1Radiology, NorthShore University HealthSystem, Evanston, IL, United States, 2Radiology, Northwestern University, Chicago, IL, United States, 3NorthShore University HealthSystem, 4Siemens Healthcare, 5Radiology, NorthShore University HealthSystem, 6Radiology, University of Chicago, Chicago, IL, United States

 
Hemodynamically significant peripheral arterial disease (PAD) can cause debilitating symptoms. Relatively long scan times preclude applying standard phase contrast technique across the entire peripheral vascular territory. We optimized a reprojected line scan PC (rLSPC) technique and tested whether it could be used to evaluate flow patterns throughout the peripheral vascular system within practical scan times. Strong agreement between rLSPC and 2D PC was obtained for mean arterial velocity and time to peak flow. The technique appears capable of providing at least a qualitative display of normal and abnormal flow patterns throughout the peripheral vascular territory within practically useful scan times.

 
1204.   Complex flow in a real-size intracranial aneurysm phantom: phase contrast MRI compared with CFD 
Pim van Ooij1,2, Annetje Guédon1,2, Joppe Schneiders1, Marcel C. M. Rutten3, Henk Marquering1,2, Charles B Majoie1, Ed vanBavel2, and Aart J Nederveen1
1Radiology, Academic Medical Center, Amsterdam, Netherlands, 2Biomedical Engineering & Physics, Academic Medical Center, Amsterdam, Netherlands, 3Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands

 
As a validation study for the use of phase contrast (PC) MRI in intracranial aneurysms high resolution time-resolved 3D PC-MRI was performed in a real-size patient-specific intracranial aneursysm phantom and compared with a CFD simulation. Qualitatively flow properties such as vortices and inflow jets were very similar. Quantitatively, small differences were found in root mean square error and velocity vector angles in voxels. This study is a first step in the application of PC-MRI in aneurysms in a clinical setting by showing that time-resolved 3D PC-MRI is capable of measuring complex flow patterns in small structures with an acceptable accuracy.

 
1205.   The Effects of Chemically Shifted Perivascular Fat in Quantitative Phase Contrast MRI 
Matthew J. Middione1,2, Abbas N. Moghadam1,3, Yutaka Natsuaki4, and Daniel B. Ennis1,2
1Department of Radiological Sciences, Diagnostic Cardiovascular Imaging Section, University of California, Los Angeles, CA, United States, 2Biomedical Physics Interdepartmental Program, University of California, Los Angeles, CA, United States, 3Department of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran, 4Siemens Medical Solutions, Malvern, PA, United States

 
Chemical shift artifacts can corrupt blood flow quantification in Phase Contrast MRI (PC-MRI). Specifically, perivascular fat can chemically shift across the vessel wall and into the lumen, thereby leading to over or underestimation of blood velocity within a vessel, depending on the imaging protocol. The degree to which chemical shift disrupts blood flow measurements depends on the readout bandwidth and the echo time. We propose that using a higher readout bandwidth reduces chemical shift artifacts in PC-MRI and concomitantly improves the accuracy of quantitative blood flow measurements.

 
1206.   Blood Flow Dynamics in DeBakey Type III Aortic Dissections using Phase Contrast MRI and 4D MRA: Quantification of Inter-Luminal Pressure Differences and Contrast Arrival Times 
Christof Karmonik1,2, Pietro Valsecchi3, Jean Bismuth1, Cassidy Duran1, Dipan J Shah1, Mark G Davies1, David Purdy4, Bill E Kline3, and Alan B Lumsden1
1The Methodist DeBakey Heart & Vascular Center, Houston, TX, United States, 2The Methodist Hospital Neurological Institute, Houston, TX, United States, 3ExxonMobil Upstream Research Company, Houston, TX, United States, 4Siemens Healthcare, Malvern, PA, United States

 
True (TL) and false lumen (FL) inter-luminal pressure differences in DeBakey type III aortic dissections (AD) were recently identified as potential predictors for disease progression and TL/FL flows may be indicative of organ perfusion. Utilizing phase contrast MRI image data from MRI exams of 10 AD patients, we developed a methodology for quantifying TL/FL inter-luminal pressure differences with Bernoulli's equation which was validated using Poiseuille's equation (R=0.74). By correlating TL and FL flows with dynamic contrast wash-in (4D MRA), we quantified time to maximum image intensity in TL, FL, liver, kidney and spleen.

 
1207.   Arterial Pulmonary Flow Analysis Post Bi-Directional Glenn Procedure 
Eric Niespodzany1, Oliver Wieben1,2, and Christopher Francois2
1Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 2Radiology, University of Wisconsin-Madison, Madison, WI, United States

 
Patients who have undergone a Bi-Directional Glenn (BDG) procedure have been seen to present with increased systemic venous pressure and reversal of flow in the superior vena cava. 4D MRI velocity mapping allows for the quantification and visualization of flow dynamics within the thoracic circulation. Here we report our initial findings on 4D flow imaging in BDG patients. This approach may lead to a greater understanding of the hemodynamics that may contribute to complications following BDG procedures.

 
1208.   Imaging CSF Flow using Spin Echo Phase Contrast Velocity Encoded MRI at 3T 
Bruce Shawn Spottiswoode1,2, and Michael Markl3
1MRC/UCT Medical Imaging Research Unit, Department of Human Biology, University of Cape Town, Cape Town, Western Cape, South Africa, 2Radiology, University of Stellenbosch, Cape Town, Western Cape, South Africa, 3Department of Radiology, Medical Physics, University Medical Center, Freiburg University, Freiburg, Germany

 
Flow sensitive MRI techniques are typically based on gradient echo (GE) imaging. GE offers a relatively low SNR for imaging cerebrospinal fluid (CSF) because of its long T1 relaxation time. We have developed a spin echo (SE) phase contrast (PC) velocity encoding sequence, and compared this to a standard GE-PC sequence using both phantom and in vivo experiments. SE-PC is only suitable for measuring slow flow because of the relatively long TE’s and the need for refocusing pulse crusher gradients. A 2-3 fold increase in SNR has been demonstrated for CSF when comparing the technique to conventional multi-phase GE-PC imaging. Reduced distortions at air-tissue interfaces and improved velocity background contrast in the flow images can also be appreciated.

 
1209.   Disagreement between Cardiovascular Magnetic Resonance and Echo-Doppler Transvalvular Pressure Gradients 
Julio Garcia1, Lyes Kadem2, Eric Larose1, and Philippe Pibarot1
1Medicine, Quebec Heart and Lung Institute, Quebec, Quebec, Canada, 2Mechanical and Industrial Engineering, Concordia University, Montreal, Quebec, Canada

 
On the current guidelines for the evaluation of aortic stenosis (AS) severity, patients are candidates for valve replacement if they have an effective orifice are (EOA) < 1.0 cm2, transvalvular pressure gradient (TPG) ≥ 40 mmHg and symptoms. Transthoracic echocardiography (TTE) is widely used to evaluate AS, however in some cases TTE measurements could have inconsistencies. In such cases cardiovascular magnetic resonance (CMR) could confirm TTE results. The aim of this study is to investigate the inconsistencies of TTE and CMR to evaluate TPG and EOA in patients with AS.

 
1210.   MRI assessment of the arterio-venous fistula 
Monica Sigovan1, Vitaliy Rayz1, Petter Dyverfeldt1, Warren Gasper2, Christopher Owens2, and David Saloner1
1Radiology, UCSF, San Francisco, CA, United States, 2Vascular Surgery, UCSF, San Francisco, CA, United States

 
Local hemodynamic factors are one of the key elements that could help explain the high rate of failure of autogenous arterio-venous fistulas (AVF), access ports that are created in long terms dialysis patients. The aim of the work presented here was to develop an MRI protocol combined with computational fluid dynamics (CFD) simulations for the detailed assessment of the hemodynamic parameters of AVFs. Simulations were carried out on patient-specific geometries obtained by manual segmentation of 3D time of flight (TOF) data. The initial results show good promise in applying this protocol to a longitudinal study of AVF progression.

 
1211.   Velocity-encoded MRI for assessment of pulmonary arterial stiffness: comparison of techniques 
Elsayed H Ibrahim1, Jean M Shaffer1, and Richard D White1
1Department of Radiology, University of Florida, Jacksonville, FL, United States

 
Two velocity-encoding MRI methods have been proposed for assessing pulmonary artery (PA) stiffness by measuring pulse-wave-velocity (PWV): transit-time (TT) and flow-area (QA). Nevertheless, no data is available that compares the two methods, especially over wide range of PWV values, or at 3.0-Tesla. In this work, twenty-five subjects were scanned using sequences optimized for spatial and temporal resolutions. PWV was measured using the TT and QA methods. Inter-method, inter-observer and intra-observer variabilities were measured. The results showed good agreement between the methods in estimating PWV, although the QA method resulted in larger variabilities. The use of 3.0-Tesla resulted in improved image-quality.

 
1212.   Quantification of blood oxygenation and flow in response to apneic challenge 
Zachary B Rodgers1, Michael C Langham1, Jeremy F Magland1, and Felix W Wehrli1
1Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States

 
Blood flow velocity and oxygenation in the femoral vessels and superior sagittal sinus were quantified to evaluate physiological responses during apneic challenge. During apnea, the arteriovenous difference narrowed, with femoral arterial HbO2 decreasing to 85-90% and venous HbO2 increasing approximately 5 %HbO2. While velocity decreased in the femoral vessels, it doubled in the SSS, consistent with the previously described normal physiologic preservation of central O2 delivery during apnea. The technique described could be used to characterize the apneic response in diseases such as sleep apnea and chronic obstructive pulmonary disease, potentially serving as a non-invasive diagnostic and prognostic tool.

 
1213.   Assessment of the clinical feasibility of phase contrast ultrashort TE 
Kieran R O'Brien1,2, Brett R Cowan1, Matthew D Robson3, Mohammad Latif4, Andrew J Kerr4, and Alistair A Young1,5
1Centre of Advanced MRI, University of Auckland, Auckland, New Zealand, 2Université de Genève, Geneva, Switzerland, 3Oxford University Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, United Kingdom, 4Cardiology, Middlemore Hospital, Auckland, New Zealand, 5Radiology & Anatomy, University of Auckland, Auckland, New Zealand

 
Intravoxel dephasing, due to long TEs, in aortic stenosis jets hinders the ability to accurately quantify the peak velocity and flow with phase contrast (PC). Previously, we proposed a PC ultrashort TE sequence, which provided superior performance in a high velocity stenotic flow phantom. Here, we investigated the clinical feasibility of this sequence. Smaller variability was observed between repeat stroke volume measurements; however, large background phase errors were present. Further optimisation of the sequence, that removes the sensitivity to background phase, could result in a more clinically reliable sequence for the MR evaluation of aortic stenosis patients.

 
1214.   Multiparameter functional MRI assessment of vascular reactivity 
Michael Charles Langham1, Cheng Li1, Emile R Mohler III2, Jeremy Magland1, and Felix Werner Wehrli1
1Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States

 
An integrated MRI protocol is presented for quantifying various measures of vascular reactivity as surrogates for assessing endothelial dysfunction. The protocol consists of simultaneously monitoring temporally resolved arterial blood flow velocity and venous oxygen saturation (SvO2) in femoral vessels during cuff-induced reactive hyperemia, along with aortic pulse-wave velocity. Impaired vascular reactivity in patients with peripheral arterial disease was marked by increased washout time, reduced upslope and overshoot of the SvO2 versus time curve, decreased shear rate and increased arterial forward flow duration. Among healthy subjects large differences were also observed, reflecting age- and lifestyle related effects on vascular reactivity.

 
1215.   Probabilistic Streamline Estimation from Accelerated Fourier Velocity Encoded Measurements 
Verena Knobloch1, Julia Kowalski2, Peter Boesiger1, and Sebastian Kozerke1
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 2Institute for Technical and Macromolecular Chemistry, RWTH Aachen, Germany

 
Conventional streamline estimation based on a 3D velocity vector field measured by phase contrast MRI suffers from noise and partial volume effects. Fourier velocity encoding measures velocity distributions per voxel which offers the possibility of probabilistic streamline estimation. To overcome the increase in scan time, acceleration techniques are employed. In this work, k-t PCA accelerated Fourier velocity encoding measurements are used for streamline estimation with Monte Carlo simulation. The resulting mean streamline is compared to conventional streamline estimation from phase contrast data. Erroneous streamlines are efficiently corrected with this approach.

 
1216.   In vivo measurement of local pulse-wave velocity in the right common carotid artery in mice with PC-Cine-MRI at 17.6 T 
Volker Herold1, Alexander Gotschy1, Christian Herbert Ziener1, Eberhard Rommel1, Wolfgang Rudolf Bauer2, and Peter Michael Jakob1
1University of Würzburg, Würzburg, Bayern, Germany, 2Medizinische Universitätsklinik, University of Würzburg

 
Pulse-wave velocity (PWV) is an important parameter for the evaluation of the arterial stiffness and cardiovascular risk. Several diseases such as hypertension and arteriosclerosis are associated with vascular remodeling and arterial stiffening. Mouse models are increasingly used to investigate functional cardiovascular parameters. MRI methods yet only have been used to quantify PWV in the murine aorta. In this study, we demonstrate the feasibility of high field MR microscopy to quantify local pulse wave velocity in the common right carotid artery.

 
1217.   Scan time reduction for three-directional phase contrast sequences: a signal processing approach 
Francesco Santini1, Michael Markl2, and Klaus Scheffler1
1Radiological Physics, University of Basel Hospital, Basel, Basel, Switzerland, 2Medical Physics, University Hospital Freiburg, Freiburg, Germany

 
The traditional phase contrast reconstruction for three-directional flow encoding extracts a single velocity point from four acquisitions, yielding a final temporal resolution equal to four times the duration of a single encoding step. The temporal resolution can be increased by a “sliding window” reconstruction, but significant distortions of the frequency content of the signal can still be present. In this work, we present a postprocessing method based on inverse signal filtering that can partially compensate for the distortion, thus effectively increasing the available bandwidth by a factor of two with respect to the conventional reconstruction, and therefore enabling an analogous decrease of the total acquisition time.

 
1218.   Improved Time-Resolved, 3D Phase Contrast Imaging through Variable Poisson Sampling and Partial Respiratory Triggering 
Marcus T Alley1, Mark J Murphy2, Kurt Keutzer2, Michael Lustig2, and Shreyas S Vasanawala1
1Radiology, Stanford University, Stanford, CA, United States, 2Electrical Engineering and Computer Science, University of California, Berkeley, CA, United States

 
Time-resolved 3-dimensional phase-contrast MR imaging (4D-PC MRI) has become more clinically viable with the advent of parallel imaging. However, undersampling patterns suitable for GRAPPA-like reconstructions often result in coherent artifacts in the final images. Here we demonstrate the use of variable density Poisson-disc/ellipse pseudorandom sampling in conjunction with the L1-SPIRiT compressed sensing reconstruction implemented on general-purpose graphics processors (GPGPU). The combined approach provides improved image quality, better artifact reduction in clinically viable acquisition and reconstruction times. In addition, we have implemented a partial respiratory triggering approach to reduce breathing artifacts with a minimal increase in scan-time.

 
1219.   Retrograde flow in the Vena Cava Superior is associated with increased Right Atrium pressure in Pulmonary Arterial Hypertension 
J. Tim Marcus1, and Anton Vonk-Noordegraaf2
1Physics & Medical Technology, VU University Medical Center, Amsterdam, Netherlands, 2Pulmonary Diseases, VU University Medical Center, Amsterdam, Netherlands

 
The aim of this study was to quantify the percentual volumetric backflow in the Vena Cava Superior by MRI flow quantification, and to assess the association beween this backflow and the systolic Right Atrium pressure in Pulmonary Arterial Hypertension (PAH) patients. Right Atrium pressure was obtained by right heart catheterization within 1 day delay from the MRI. This association was significant (n=29 patients, r=0.55, p=0.0018), which explains, from a hemodynamic point of view, why the Right Atrium pressure has a significant prognostic value in PAH.

 
1220.   Voxel-wise Quantitative assessment of Myocardial Perfusion: a Comparison of Four Different Deconvolution Algorithms Using Real Flow Values 
niloufar Zarinabad nooralipour1, Amedeo Chiribiri1, Gilion Hautvast2, Aruna Vishnu Arujuna1, Eike Nagel1, and philip Batchelor1
1The Centre of Excellence in Medical Engineering, kings college London, London, United Kingdom, 2Imaging Systems- MR, Philips Healthcare, Netherlands

 
In this study four different deconvolution algorithms have been applied to voxel-wise analysis of first-pass myocardial perfusion MR data. We aimed to test robustness of these methods to noise and to evaluate the accuracy of the perfusion estimates by validating the estimated perfusion values in a hardware perfusion phantom with true perfusion values, measured by means of precision flow-meters. This study demonstrated that Auto-Regressive Moving Average model is the least sensitive method to noise, while achieving almost similar accuracy to exponential basis deconvolution, which is the superior model in terms of accuracy of estimation, and compares favourably over the Fermi function modelling quantification method

 
1221.   MR Flow Imaging Beyond the Mean Velocity: Estimation of the Skew and Kurtosis of Intravoxel Velocity Distributions 
Petter Dyverfeldt1,2, Andreas Sigfridsson1, Hans Knutsson1, and Tino Ebbers1
1CMIV and Linköping University, Linköping, Sweden, 2University of California San Francisco, San Francisco, CA, United States

 
MR flow imaging has proved to be a valuable tool in improving the understanding and diagnostics of cardiovascular disease. The most common MR flow imaging method is phase-contrast velocity mapping, which estimates the mean velocity of a voxel. However, MR may permit more advances flow analysis. This study goes beyond the mean velocity of a voxel and evaluates the potential of MRI for the quantification of skew and kurtosis of intravoxel velocity distributions. Proof-of-concept is demonstrated based on simulated MR measurements of skew and kurtosis in post-stenotic flow.

 
1222.   Acclerated Dual Venc Phase Contrast VIPR in Healthy Volunteers 
Elizabeth Janus Nett1, Alex Frydrychowicz2, Kevin M Johnson1, Christopher J Francois2, Eric Schrauben1, and Oliver Wieben1,2
1Medical Physics, University of Wisconsin, Madison, Wisconsin, United States, 2Radiology, University of Wisconsin, Madison, Wisconsin, United States

 
Choosing a proper velocity encoding (Venc) setting is challenging when covering large vascular territories with a single 4D PC MRI acquisition. Dual Venc acquisitions can improve the VNR while maintaining dynamic range utilizing (1) a low Venc data set to provide a good VNR and (2) a high Venc data set to identify and correct for velocity aliasing. In this in-vivo study, we compare flow measurements from an accelerated dual Venc PC VIPR acquisition with those obtained with a standard PC VIPR and targeted standard Cartesian 2D phase contrast (2D PC) acquisitions.

 
1223.   Hemodynamic simulations of subjects with vertebro-basilar anomalies 
Amanda K. Wake1, James Christopher Gatenby2, and John C. Gore1
1Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States, 2Department of Radiology, University of Washington, United States

 
Subject-specific computational fluid dynamics (CFD) models were constructed for investigating the flow field in the vertebro-basilar system of subjects with geometric anomalies.

 
1224.   Can a single phase contrast aortic flow acquisition be used to define a surrogate marker of cardiac index? 
Frederique Frouin1,2, Muriel Lefort1,2, Mourad Bensalah1,3, Alain De Cesare1,2, Claire Pellot-Barakat1,2, Elie Mousseaux1,3, and Alain Herment1,2
1UMR_S 678, Inserm, Paris, France, 2UMR_S 678, UPMC, Paris, France, 3HEGP, AP-HP, Paris, France

 
Providing that the underestimation (15%) of the cardiac index would be compensated, the single PC aortic acquisition could be an interesting alternative to a whole cardiac acquisition to estimate the cardiac index. The automated processing of aortic acquisition enables to drastically reduce the operator’s intervention. It would enable a reduction of the acquisition duration, which is highly desirable in combined vascular and brain protocols applied to an aging population. Moreover, ascending aortic strain and pulse wave velocity in the aortic arch (requiring a supplementary sagittal acquisition), which are considered as promising biomarkers of vascular aging, could be equally estimated easily.

 
1225.   MRI estimate of central and peripheral pulse-wave velocity via velocity-encoded projections 
Michael Charles Langham1, Cheng Li1, Jeremy Magland1, and Felix Werner Wehrli1
1Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States

 
Numerous studies have provided evidence of elevated aortic pulse-wave velocity (PWV) to complement the traditional cardiovascular disease risk factors. Quantification of peripheral PWV (e.g. iliac, femoral and popliteal arteries) has received much less attention even though some studies indicate peripheral PWV to be preferable since, unlike central artery PWV, peripheral PWV does not increase with age and its elevation may therefore be more specific to disease. Here we demonstrate a projection-based MRI method for quantification of PWV at multiple arterial segments as a possible means for detection of early endothelial dysfunction.

Traditional Posters : Cardiovascular Imaging
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Vessel Wall Imaging (Non Coronary)

 
Thursday May 12th
Exhibition Hall  13:30 - 15:30

1226.   Inflammatory Atherosclerotic Plaque Can Be Reproducibly Assessed By 3T Dynamic Contrast Enhanced MRI for Multi-Center Studies 
Huijun Chen1, Jie Sun1, William S Kerwin1, Niranjan Balu1, Daniel S Hippe1, Daniel Isquith1, Yunjing Xue1, Suzanne Peck1, Chun Yuan1, Kevin O'Brien1, and Xue-Qiao Zhao1
1University of Washington, Seattle, WA, United States

 
Inflammation plays an important role in both atherosclerotic plaque progression and rupture. Kinetic parameters derived from DCE-MRI (Ktrans and vp), has been proved to correspond with permeability and blood supply, which are related to inflammatory processes. However, the inter-scan reproducibility of these kinetic parameters in atherosclerotic plaque has not been investigated for multi-center studies, which is essential for prospective studies. In this study, we established the reproducibility of Ktrans and vp and analyzed the sample size needed to detect changes of these parameters, using 3T scanners in a multi-center design.

 
1227.   Intracranial Arterial Wall Imaging using 3D High Isotropic-Resolution Black Blood MRI at 3.0 T 
Ye Qiao1, David A. Steinman2, Qin Qin1, Maryam Etesami1, Michael Schär1,3, Brad C, Astor1, and Bruce A. Wasserman1
1The Johns Hopkins Hospital, Baltimore, MD, United States, 2University of Toronto, Toronto, ON, Canada, 3Philips Healthcare, Cleveland, OH, United States

 
Only a few studies have attempted to image intracranial atherosclerosis by MRI, all using a 2D black blood MRI technique. This approach is suboptimal for imaging intracranial vessel walls given the small size and inherent curving course of these vessels. We developed a 3D high-resolution Volumetric ISotropic TSE Acquisition (VISTA) sequence (0.5 isotropic) for evaluating intracranial vessels at 3.0T to minimize the partial volume effects and signal constraints of 2D sequences. Our sequence provides reliable measurements of intracranial vessel wall size and may make it possible to discern pathological changes from the normal vessel wall.

 
1228.   Association between carotid plaque characteristics and cerebral white matter lesions 
Robert Kwee1, Paul Hofman1, Ed Gronenschild2, Robert van Oostenbrugge2, Werner Mess2, Johannes ter Berg3, Cees Franke4, Arthur Korten5, Bé Meems6, Jos van Engelshoven2, Joachim Wildberger2, and Eline Kooi2
1Maastricht University Medical Center, Maastricht, Limburg, Netherlands, 2Maastricht University Medical Center, Netherlands, 3Orbis Medical Center Sittard, Netherlands, 4Atrium Medical Center Parkstad Heerlen, Netherlands, 5Laurentius Hospital Roermond, Netherlands, 6VieCuri Medical Center, Netherlands

 
In TIA/stroke patients with carotid stenosis, we found no associations between carotid plaque characteristics and ipsilateral white matter lesion severity and progression over a one-year period. This suggests that there is no causal relationship between carotid plaque vulnerability and the occurrence of white matter lesions.

 
1229.   Dynamic Contrast Enhanced MRI of Carotid Plaque: Comparison of Pharmacokinetic Models 
Michaela Elisabeth Gaens1, Stefan Rozel1, Matthijs Lipperts1,2, Robert M. Kwee1, Karolien Jaspers1, Mat J. A. P. Daemen1, Joachim E. Wildberger1, Walter H. Backes1, and Marianne Eline Kooi1
1Department of Radiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Center, Maastricht, Netherlands, 2Department of ICMT, Atrium Medical Center, Heerlen, Netherlands

 
Dynamic contrast-enhanced MRI can be used to determine pharmacokinetic parameters of carotid plaques. These parameters are connected with plaque properties such as neovascularization, an indicator for plaque vulnerability. In this study, three known models (Tofts, Extended Tofts, Patlak) were compared with regard to their ability to describe DCE-MRI data acquired for 29 patients with moderate (50-69 %) carotid stenosis. Comparison of overall fit error and uncertainties in estimated parameter values show that the Patlak model is most suited to describe data acquired with the presently used scan protocol.

 
1230.   Characterization of Morphological Features and Critical Mechanical Condition along Carotid Plaques using in vivo MRI and Finite Element Simulation 
Chengcheng Zhu1, Zhongzhao Teng1, Umar Sadat1, Victoria E Young1, Martin J Graves1, Zhiyong Li1,2, and Jonathan H Gillard1
1Department of Radiology, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom, 2School of Biological Science & Medical Engineering, Southeast University, Nanjing, Jiangsu, China, People's Republic of

 
The rupture of atherosclerotic carotid plaque is one of the main causes of ischemic cerebrovascular events such as stroke. Carotid plaque rupture/ulceration is often located in the region proximal to the maximum stenosis. We aim to quantify both the morphological and mechanical features along the plaque to identify high risk factors for rupture.

 
1231.   In Vivo singleshot T1 and T2* Measurements of Atherosclerosis Plaques in Symptomatic and Asymptomatic Patients Using 2D ss-SGSTEPI Technique 
Seong-Eun Kim1, Eun-Kee Jeong1, Xianfeung Shi2, Gerald S Treiman3, and Dennis L Parker1
1Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Utah, United States, 2Brain Research Institute, University of Utah, 3Department of Veterans Affairs, VASLCHCS, Salt Lake City, Utah

 
Atherosclerotic plaque characterization by MRI is generally based on the signal intensities and morphological appearance in multi-contrast images, but conventional contrast images are unable to provide the full quantification of high risk plaque components. Iron has consistently been found in higher concentrations in atherosclerotic plaque compared to tissue. Iron may be incorporated into hemoglobin or bound to the storage proteins ferritin and hemosiderin. It has been reported that intraplaque T2* measurement distinguished symptom-producing from non-symptom producing plaques in patients. In this work we introduce simultaneous measurement of T1 and T2* of atherosclerotic plaque using a novel sigleshot sequence, 2D ss-SGSTEPI.

 
1232.   Increasing spatial resolution alters measurement variability of carotid plaques 
Diederik Frank van Wijk1, Raphael Duivenvoorden1, D F Enklaar1, Rob J van der Geest2, Eric de Groot1, Erik S.G Stroes1, and Aart J Nederveen3
1Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands, 2Radiology, Leiden University Medical Center, Leiden, Netherlands, 3Radiology, Academic Medical Center, Amsterdam, Netherlands

 
Early detection of atherosclerotic plaques that are prone for rupture can improve preventive strategies in clinical practise. MRI has the promise to identify plaque morphological characteristics that are the hallmark of the vulnerable plaque. Here, we show that high and low spatial resolution measurements change the accuracy and reproducibility of different parameters of the atherosclerotic plaque in a population with carotid atherosclerosis.

 
1233.   Scan-Rescan Reproducibility of Carotid Geometric Parameters using Bright Blood MRI at 3.0T 
Yunjing Xue1, Daniel S Hippe1, Hunter R Underhill1, Marina S Ferguson1, Niranjan Balu1, Rui Li2, Huijun Chen1, Li Dong3, Feiyu Li4, Gador Canton1, and Chun Yuan1
1Vascular Imaging Laboratory, Radiology, University of Washington, Seattle, WA, United States, 2Center for Bio-Medical Imaging Research, Tsinghua University, Beijing, China, People's Republic of, 3Department of Radiology, Beijing Anzhen Hospital, Beijing, China, People's Republic of, 4Department of Radiology, Peking University First Hospital, Beijing, China, People's Republic of

 
Carotid bifurcation geometry has been identified implicated as a risk factor for the development of atherosclerotic plaque. Geometrical factors associated with flow propertiesfeatures can be assessed from 3D models derived from either bright blood or black blood MRI. Reproducibility of these geometrical parameters is important for longitudinal studies of risk assessment. While reproducibility of black-blood derived geometry has been previously reported, bright blood reproducibility is unknown. We show that geometric parameters assessed by bright blood MRI are comparable to those derived from black blood MRI.

 
1234.   Interleaved LOcal excited Black Blood (LOBBI) and Bright Blood MRI for improved vessel wall DCE 
Jinnan Wang1, Huijun Chen2, Gregory J Wilson3, Niranjan Balu2, William S Kerwin2, Chun Yuan2, and Peter Boernert4
1Clinical Sites Research Program, Philips Research North America, Seattle, WA, United States, 2University of Washington, 3Philips Healthcare, 4Philips Research Europe

 
Dynamic contrast enhanced MRI has been used to quantify the inflammation in atherosclerotic plaques. The current technology of using mere bright or black blood contrast images, however, can not achieve the required high temporal resolution for AIF and high spatial resolution for vessel wall. In this abstract, an inverleaved Black and Bright blood DCE MRI was proposed. A novel LOBBI sequence was used to eliminate the signal intereference between Black and Bright blood images and the technique was validated in a flow phantom experiment.

 
1235.   Carotid plaques in TIA and stroke patients: one-year follow-up study by magnetic 
Robert Kwee1, Robert van Oostenbrugge2, Werner Mess2, Martin Prins2, Rob van der Geest3, Johannes ter Berg4, Cees Franke5, Arthur Korten6, Bé Meems7, Jos van Engelshoven2, Joachim Wildberger2, and Eline Kooi2
1Maastricht University Medical Center, Maastricht, Limburg, Netherlands, 2Maastricht University Medical Center, Netherlands, 3Leiden University Medical Center, Netherlands, 4Orbis Medical Center Sittard, Netherlands, 5Atrium Medical Center Parkstad Heerlen, Netherlands, 6Laurentius Hospital Roermond, Netherlands, 7VieCuri Medical Center Venlo, Netherlands

 
We investigated the natural course of carotid plaque progression in TIA/stroke patients with ipsilateral <70% carotid stenosis, by using serial multisequence magnetic resonance imaging. The results of our study show that there is inward plaque remodeling over a 1-year period, while features of plaque vulnerability generally remain unchanged.

 
1236.   T2-Prepared Segmented 3D-Gradient-Echo for Fast T2-Weighted High-Resolution Three-Dimensional Imaging of the Carotid Artery Wall at 3T: A Feasibility Study 
Jian Zhu1,2, Axel Bornstedt1, Genshan Ma2, Nico Merkle1, Naifeng Liu2, Wolfgang Rottbauer1, and Volker Rasche1
1Internal Medicine II, University of Ulm, Ulm, Germany, 2Department of Cardiology, Zhongda Hospital, Nanjing, Jiangsu, China, People's Republic of

 
In this study, the use of a fast gradient echo sequence with T2 preparation is investigated for generating a T2 weighted image contrast similar to a multi-spin echo approach. The sequence has been applied to volumetric imaging of the carotid artery wall and compared to the conventional multi-spin echo technique. Using the suggested technique enabled a significant reduction of the image acquisition time up to a factor of three, with almost maintained image contrast.

 
1237.   MRI-detected Intraplaque Hemorrhage in an Animal Model 
Stephanie Elaine GarWai Chiu1, Alan R Moody1,2, James Q Zhan2, and General Leung1
1Medical Biophysics, University of Toronto, Toronto, Ontario, Canada, 2Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

 
Intraplaque hemorrhage (IPH) detected with T1-weighted MRI has been shown to predict future ischemic events in both symptomatic and asymptomatic carotid patients. Despite the clinical relevance of IPH, there are few animal IPH models and an absence of data concerning MRI of IPH in such animal models. This study explores the suitability of a rabbit model of intraplaque-delivered red blood cells for MRI studies of in vivo IPH and presents evidence of MRI-detected IPH in this model using high resolution, T1-weighted sequences.

 
1238.   MRI of Bone Marrow Cell-Mediated Interleukin-10 Gene Therapy of Atherosclerosis 
Jihong Sun1,2, Xubin Li1, Hongqing Feng1, Huidong Gu1, Tiffany Blair1, Jiakai Li1, Yanfeng Meng1, Feng Zhang1, and Xiaoming Yang1,2
1Image-Guided Bio-Molecular Interventions Section, Radiology, University of Washington School of Medicine, Seattle, WA, United States, 2Radiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China, People's Republic of

 
Interleukin-10 (IL10) gene-transduced-bone marrow cells (BMC) were labeled with Feridex, and then transplanted into atherosclerotic ApoE-/- mice. In vivo MRI presented signal voids of the aorta walls due to the migration of the IL10/Feridex-BMCs into atherosclerotic lesions. Subsequent histologic measurements showed that the average size of atherosclerotic lesions in the mouse group with IL10/Feridex-BMC transplantation was significantly less than those in control mouse groups with Feridex-BMC transplantation or no BMC transplantation. This study demonstrates the potential of using in vivo MRI to track IL10/Feridex-BMCs recruited to atherosclerotic lesions, where IL10 genes may function to prevent the progression of atherosclerotic lesions.

 
1239.   LOcal excitation Black Blood Imaging (LOBBI) for local transmission coil at high field MRI (7T and above) 
Jinnan Wang1, Niranjan Balu2, Gregory J Wilson3, Chun Yuan2, and Peter Boernert4
1Clinical Sites Research Program, Philips Research North America, Seattle, WA, United States, 2University of Washington, 3Philips Healthcare, 4Philips Research Europe

 
High field MRI provides a unique approach to characterize atherosclerotic plaques with improved SNR and new contrast. The unavailability of global T/R coil on high field systems due to homogeneity issues, however, limits its further application in black blood imaging. No current BB techniques works without global excitation due to inflow effects. This abstract proposes a new imaging that achieves effective BB with only local excitation and a flow phantom experiment is also conducted for validation.

 
1240.   Reproducibility of T2-measurements in human carotid plaques 
Diederik Frank van Wijk1, S Gonçalves2, Raphael Duivenvoorden3, D F Enklaar3, Paul F. Groot2, J. B. Warntjes4,5, Erik S Stroes3, and Aart J Nederveen2
1Vascular medicine, Acedemic Medical Center, Amsterdam, Netherlands, 2Radiology, Academic Medical Center, Amsterdam, Netherlands, 3Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands, 4Center for Medical Imag Science and Visualization, Linköping University, Linköping, Sweden, 5SyntheticMR AB, Linköping, Sweden

 
The cornerstone for preventive treatment strategies of patients at increased risk for an atherosclerotic event is early recognition of the prone to rupture plaque. MRI has recently shown to identify morphological characteristics, such as the intraplaque haemorrhage and the lipid rich necrotic core, which are considered to be important components of the vulnerable plaque. Absolute T2 values can accurately discriminate and indentify different tissues in a wide range of conditions and patients. Here, we used MR relaxometry to determine the absolute T2-values of two repetitive measurements in human carotid plaques.

 
1241.   ECG–triggering improves blood suppression in abdominal aortic imaging using the quadruple inversion recovery sequence. 
Sarah Anne Peel1, Tarique Hussain1, Marina Cecelja2, Abeera Abbas3, Gerald Greil1, and René M Botnar1
1Division of Imaging Sciences and Biomedical Engineering, King's College London, London, London, United Kingdom, 2NIHR Comprehensive Biomedical Research Centre, Guy's and St Thomas' NHS Foundation Trust / King's College London, United Kingdom, 3Academic Department of Surgery, Cardiovascular Division, King's College London, United Kingdom

 
The quadruple inversion recovery (QIR) pre-pulse was originally developed for carotid vessel wall imaging without cardiac triggering. As aortic blood flow varies considerably during the cardiac cycle, we hypothesize that ECG-triggering may improve blood suppression when applying the QIR sequence in the aorta. The QIR pre-pulse was successfully combined with ECG-triggering and small FOV 'zoom' imaging to accelerate the scan time without fold over artifacts. The zoom QIR-TSE sequence was used to image the abdominal aorta in volunteers both before and after contrast administration. The ECG-triggered QIR images show improved blood suppression and image quality compared to un-triggered scans.

 
1242.   Enhanced Intraplaque Hemorrhage Delineation Method in Slab-selection Phase-sensitive Inversion-recovery (SPI) Sequence with MRI 
Dongxiang Xu1, Jinnan Wang2, Jie Sun3, and Chun Yuan3
1Radiology, University of Washington, Seattle, WA, United States, 2Philips Research North America, 3University of Washington

 
Atherosclerosis is the number one killer in the world. Previous studies have shown that intraplaque hemorrhage (IPH) into the carotid atherosclerotic plaque is a major factor causing plaque instability and progression. Thus, IPH is critical to evaluation of carotid atherosclerotic disease. The Slab-selection Phase-sensitive Inversion-recovery MRI sequence has improved IPH evaluation compared to others imaging sequences. Using this technique, we developed an enhanced mean-shift model to auto-detect IPH and applied it to in vivo MRI data. The statistical analysis results show this algorithm has 100% sensitivity, 95% specificity and a high correlation with human evaluation

 
1243.   In Vivo 3D High Resolution Apparent Diffusion Coefficient (ADC) maps of Carotid Artery Atherosclerosis Plaques Using 3D singleshot Inner Volume Stimulated EPI (3D ss-IV-STEPI) Technique 
Seong-Eun Kim1, Eun-Kee Jeong1, Xianfeng Shi2, Gerald S Treiman3, and Dennis L Parker1
1Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Utah, United States, 2Brain Research Institute, University of Utah, 3Department of Veterans Affairs, VASLCHCS, Salt Lake City, Utah

 
To improve the sensitivity and specify of plaque component identification in ADC maps a high resolution 3D DWI technique is desirable. 3D ss-IV-STEPI technique has been developed to acquire a high resolution DWI of a localized region such as the carotid artery. This technique acquires the total k-space of a limited 3D volume after a single diffusion-preparation. Inner volume technique is used to reduce the time required for EPI readout of each complete k-space and reduce blurring and susceptibility artifacts. In this work we present the first in vivo high resolution 3D DWI of the atherosclerosis plaques using the 3D-ss-IV-STEPI.

 
1244.   Gd-based protein cage nanoparticles for vascular wall MRI at 3T 
Hisanori Kosuge1, Toshiro Kitagawa1, Masaki Uchida2, Lars Liepold2, David Morris3, Peter E Prevelige Jr.3, Trevor Douglas2, and Michael V McConnell1
1Cardiovascular Medicine, Stanford University, Stanford, CA, United States, 2Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States, 3Microbiology, The University of Alabama at Birmingham, Birmingham, AL, United States

 
Protein cage nanoparticles (PCNs) have shown promise for molecular/cellular imaging of cardiovascular disease and cancer. PCNs incorporating iron oxide have been used as susceptibility agents for MRI, but T1-shortening agents are preferred clinically. The PCN structure can incorporate targeting peptides and can also enhance the T1 effect of Gd by slowing rotational correlation time and by providing multiple Gd binding domains. We demonstrate that Gd-based PCNs show strong r1 values in vitro plus signal enhancement in vivo of carotid and aortic vascular disease, with low Gd dosing.

 
1245.   In Vivo Assessment of Abdominal Aortic Aneurysm in the elastase-induced mouse model 
Michel A Bartoli1, Frank Kober1, Patrick J Cozzone1, and Monique Bernard1
1Centre de Resonance Magnetique Biologique et Medicale, Faculte de Medecine, Universite de la Mediterranee, Marseille, Provence, France

 
The elastase perfusion mouse model is one of the most reliable animal models of Abdominal Aortic Aneurism formation. This MRI study at 11.75T aimed at evaluating the reliability of longitudinal in vivo aortic diameter and wall thickness measurements in mice after aortic perfusion with elastase or with heat-inactivated elastase in control animals. Vessel diameter was significantly greater in elastase-perfused mice compared to controls with both the optic grid measurement and the MRI measurement of the outer diameter. Aortic wall area was significantly greater in elastase mice compared with control mice. Optic and MRI measurements showed good correlation.

 
1246.   Zoom accelerated Quadruple Inversion Recovery imaging for fibrous cap visualization in the abdominal aortic aneurysm 
Tarique Hussain1, Sarah Peel1, Abeera Abbas1, Matthew Waltham1, Gerald Greil1, and Rene Botnar1
1King's College London, Westminster, London, United Kingdom

 
In this study, the Abdominal Aortic aneurysm is used as a model to show the ability of Zoom-accelerated Quadruple inversion Recovery to demonstrate post-contrast enhancement of the fibrous cap. The technique has been implemented here for cardiovascular imaging by adapting timing for ECG-gating. The advantage over traditional techniques is that exactly the same inversion times are used before and after contrast administration. This removes the implicit quantification bias of traditional sequences.

 
1247.   Comparison of SWI and DIR-prepared TSE Femoral Artery Wall Imaging 
Qi Liu1,2, Qi Yang3, Zhaoyang Fan1, and Debiao Li1,4
1Cedars-Sinai Medical Center, Los Angeles, CA, United States, 2Northwestern University, Chicago, IL, United States, 3Xuanwu Hospital, Beijing, China, People's Republic of, 4UCLA, Los Angeles, CA, United States

 
Despite the benefits of SWI vessel wall imaging, namely blood flow independence, three dimensional coverage, and sensitivity to calcification, the accuracy of SWI in morphological measurement has yet to be addressed. Here we compared SWI with the reference method, single slice DIR turbo spin echo (TSE), on measuring femoral artery lumen and wall size.

 
1248.   Evaluation of aortic distensibility in wild type and ApoE-knock-out mice at 9.4 T. 
Peter Fries1, Florian Custodis2, Andreas Müller1, Roland Seidel1, Alexander Massmann1, Arno Bücker1, and Günther Schneider1
1Clinic of Diagnostic and Interventional Radiology, Saarland University Hospital, Homburg, Saarland, Germany, 2Department of Cardiology, Saarland University Hospital, Homburg, Saarland, Germany

 
The aim of this study was to compare the aortic distensibility (AD) in wild-type (C57/BL6, n=6)) and cholesterol fed ApoE-knock-out mice (ApoE-/-, n=6), a model of atherosclerosis, by means of cine MRI at 9.4 T. A self-gated cine sequence (Intragate®) was acquired perpendicular to the ascending aorta. AD was defined as the difference of the cross-sectional vessel area at endsystole and enddiastole. ApoE-/- mice demonstrated a significantly lower AD and a larger cross-sectional vessel areas at enddiastole. The reduced AD in this model of lipid induced atherosclerosis may be evaluated in vivo with MRI at 9.4 T.

 
1249.   Low b-value DWI in assessment of large vessel vasculitis 
James F Glockner1, and Christine U Lee1
1Radiology, Mayo Clinic, Rochester, MN, United States

 
Low b-value DWI was assessed as an alternative technique for demonstrating mural edema in patients with large vessel vasculitis. The robust black blood effect, significant increased signal intensity in patients with active disease, and rapid acquisition times of low b-value DW imagse compared favorably with conventional ecg gated or non-gated fast spin echo acquisitions in this small feasibility study.

 
1250.   Identification and quantification of atherosclerosis in arterial vessels using an interventional 3T loopless detector 
Di Qian1,2, and Paul A Bottomley1,2
1Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland, United States, 2Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, United States

 
Fibrous cap thickness is key to assessing vulnerable atherosclerotic plaque. MRI is intrinsically well-suited for plaque imaging, but has lacked the spatial resolution needed to resolve the cap and other pathologies. At 3T, the intravascular loopless MRI detector offers ~4-fold higher signal-to-noise ratio than at 1.5T, and can be made safe from RF heating. Here we investigate its use for identifying plaques for subsequent high-resolution 80µm imaging of lesion and vessel wall morphology in diseased human arterial specimens in vitro, correlating MRI measurements of fibrous caps with histology. Feasibility of the approach is demonstrated in a rabbit aorta in vivo.

 
1251.   Dynamic T2prep for flow-independent vessel wall imaging 
Marcelo E Andia1, and Rene M Botnar1
1Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom

 
In this work we present a novel technique for flow-independent vessel wall imaging based on the differences in T2 relaxation time of arterial blood and surrounding tissues using a T2prep prepulse. The technique is based on the acquisition and subtraction of two data sets, one obtained with T2prep(+) and without T2prep(-). This allows nulling the signal of arterial blood while maintaining the signal of muscle and vessel wall. The result of the subtraction results in a flow-independent black blood vessel wall image.

Traditional Posters : Cardiovascular Imaging
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Coronary Artery & Vessel Wall Imaging

 
Monday May 9th
Exhibition Hall  14:00 - 16:00

1252.   Simultaneous left and right coronary artery wall imaging with highly efficient beat-to-beat respiratory motion correction 
Andrew David Scott1,2, Jennifer Keegan1,2, and David Firmin1,2
1Cardiovascular Magnetic Resonance Unit, Imperial College London, London, United Kingdom, 2Cardiovascular Magnetic Resonance Unit, The Royal Brompton and Harefield NHS Foundation Trust, London, United Kingdom

 
MR vessel wall imaging is commonly performed with alternate R-wave cardiac gating which improves SNR and robustness to variations in RR-interval, but results in one redundant cardiac cycle in every two. The redundant cardiac cycle has been used to image an additional parallel slice in 2D carotid wall imaging. Beat-to-beat respiratory motion correction (B2B-RMC) can obtain 3D coronary wall images with ~100% respiratory efficiency. We have used the redundant cardiac cycle to acquire an additional 3D volume in coronary vessel wall imaging with B2B-RMC, resulting in simultaneous targeted high resolution left and right 3D coronary vessel wall imaging in ~10minutes.

 
1253.   Self-Gated Free Breathing 3D Coronary Cine Imaging With Enhanced Artery Contrast by Exploiting the Simultaneously obtained Water and Fat Visualization 
Jing Liu1, Thanh D Nguyen1, Yanchun Zhu1, Pascal Spincemaille1, Jonathan W Weinsaft1, Martin R Prince1, and Yi Wang1
1Radiology, Weill Cornell Medical College, New York, NY, United States

 
A respiratory and cardiac self-gated free-breathing 3D cine SSFP imaging technique provides both water and fat visualization of the coronary arteries. Multi-echo hybrid radial sampling has been approved to be high efficient at data acquisition and robust to motion. It has been exploited for generating self-gating signals without extra cost of scan time, by mapping the k-space center along the slice encoding direction intensity-weighted position information, from which both respiratory and cardiac motions are derived. In this study, data sets at different echo times are exploited for separating water and fat signals. The conventional coronary imaging techniques acquire data during a limited acquisition window at the middle diastolic phase, which requires subject dependent trigger delay. And the preparation pulses such as navigation pulse, fat and myocardium suppression pulses interrupt the steady states and cause artifacts. Our proposed water and fat separation based self-gated cine image technique have the advantages of avoiding the extra requirements and preparation pulses. Combination of the water and fat images improves the coronary artery contrast.

 
1254.   Cross-sectional Dixon-Enhanced Spiral Cine Coronary Artery Magnetic Resonance Imaging at 3T 
Harsh Kumar Agarwal1, Peter Koken2, Michael Schär3, Jing Yu1, Allison G Hays1, Holger Eggers2, Robert G Weiss1, Peter Börnert2, and Matthias Stuber4,5
1Johns Hopkins University, Baltimore, MD, United States, 2Philips Research Laboratories, Hamburg, Germany, 3Philips Healthcare, Cleveland, OH, United States, 4Department of Radiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland, 5Center for Biomedical Imaging (CIBM), Lausanne, Switzerland

 
Three Tesla cross-sectional spiral coronary MRI has successfully been used for the measurement of endothelial function in healthy adults and in patients with coronary artery disease. However, increased B0 inhomogeneity at high magnetic field strength may adversely affect the image quality and the quantitative measurements. Therefore, we have combined the 3 point Dixon technique with cross sectional spiral coronary MRI to separate water and fat signal on the one hand and to correct for off-resonance artifacts using sliding window conjugate phase reconstruction on the other hand.

 
1255.   Respiratory Navigator with Adaptive Acceptance Gating Window Size and Fixed Scan Time for Coronary MRI 
Mehdi Hedjazi Moghari1, Alan O'connor1, Warren J Manning1, and Reza Nezafat1
1Dept. of Medicine (Cardiovascular Div.), Beth Israel Deaconess Medical Center, Harvard Medical Sch., Boston, MA, United States

 
Compensating for the heart respiratory motion using prospective navigators prolongs scan time with a non-deterministic total acquisition time. In this study, we propose a new adaptive navigator gating where fixed navigator efficiency is used for enforcing temporal changes in the gating window during the scan.

 
1256.   2D image-based respiratory motion estimation for free-breathing coronary MRA 
Taehoon Shin1, Holden H Wu1,2, Michael V McConnell1,2, and Dwight G Nishimura1
1Electrical Engineering, Stanford University, Stanford, CA, United States, 2Cardiovascular Medicine, Stanford University, Stanford, CA, United States

 
Correction for respiratory motion remains a major challenge in free-breathing coronary MRA. Motion estimation directly from the heart is potentially superior to conventional diaphragmatic navigator, and several methods based on DC or 1D projection signals have been proposed. We propose a 2D image-based respiratory navigator which allows accurate estimation of SI and AP motion of the heart. Despite the use of 2D images, the navigator acquisition time was significantly shortened by utilizing preserved motion correlation between aliased images. The feasibility of the proposed approach is demonstrated by phantom and in-vivo experiments.

 
1257.   prospective respiratory motion correction with an image based navigator 
Markus Henningsson1, Jouke Smink2, and Rene M Botnar1
1Division of Imaging Sciences & Biomedical Engineering, King's College London, London, United Kingdom, 2Philips Healthcare, Best, Netherlands

 
In this work a novel 2D navigator (2Dnav) is proposed, which prospectively corrects for translational motion in foot-head and left-right direction. The 2Dnav was implemented as a Cartesian bSSFP sequence and used a template matching algorithm for motion estimation. The 2Dnav was compared to a diaphragmatic 1D navigator with a tracking factor of 0.6 at 10 mm gating window and no gating. Visual assessment preferred the 2Dnav over the 1Dnav for no gating while there was no significant difference for a gating window of 10mm.

 
1258.   Self-navigation with a 1D pencil beam navigator 
Markus Henningsson1, and Rene M Botnar1
1Division of Imaging Sciences & Biomedical Engineering, King's College London, London, United Kingdom

 
Self-navigators offers a “model free” alternative to diaphragmatic navigators for respiratory motion correction in coronary MRA. In this study we have investigated the use of a pencil beam 1D navigator (1Dnav) with large diameter (~100mm) and small flip angle (10°) for direct measurements of the respiratory motion of the heart, comparing it to the conventional approach which uses a 1Dnav positioned on the diaphragm and a tracking factor of 0.6. We show that the 1Dnav is feasible for self-navigation and shows improved motion compensation compared to the diaphragmatic 1D navigator.

 
1259.   Robust and Fully Integrated One Dimensional Respiratory Self-Navigation for Whole-Heart Coronary MRI 
Davide Piccini1, Arne Littmann2, Sonia Nielles-Vallespin2, and Michael O. Zenge2
1Pattern Recognition Lab, University of Erlangen-Nuremberg, Erlangen, Germany, 2MR Applications and Workflow Development, Healthcare Sector, Siemens AG, Erlangen, Germany

 
Conventional navigator-gated techniques for coronary MRI are burdened with low scan-time efficiency and sub-optimal precision. Self-navigating methods promise to overcome these limitations using the positional information of the heart directly accessible in the readouts used for imaging. These methods, however, suffer from the presence of signal form chest wall, arms and liver which can render the respiratory motion detection impossible. In the current work, an innovative method to efficiently suppress such unwanted signal is presented and robust self-navigation is achieved. This method was fully integrated into 3D radial whole-heart coronary imaging and was compared with conventional navigator-gated imaging in volunteers.

 
1260.   Reduction of Pulmonary Vein Blood Inflow Artifact in Free Breathing Left Atrial Late Gadolinium Enhancement MRI 
Mehdi Hedjazi Moghari1, Dana C Peters1, Jouke Smink2, Lois Goepfert1, Kraig V Kissinger1, Beth Goddu1, Thomas H Hauser1, Mark E Josephson1, Warren J Manning1, and Reza Nezafat1
1Dept. of Medicine (Cardiovascular Div.), Beth Israel Deaconess Medical Center, Harvard Medical Sch., Boston, MA, United States, 2Philips Healthcare, Netherlands

 
Conventional navigator gated imaging sequence for left atrial late gadolinium enhancement (LGE) results in blood enhancement artifact. In this study, we investigated a modified free-breathing LGE sequence that minimizes this artifact.

 
1261.   Multi-Phase Coronary MR Angiography Using a 3D Cones Trajectory 
Holden H Wu1,2, Bob S Hu2,3, Dwight G Nishimura2, and Michael V McConnell1,2
1Cardiovascular Medicine, Stanford University, Stanford, CA, United States, 2Electrical Engineering, Stanford University, Stanford, CA, United States, 3Palo Alto Medical Foundation, Palo Alto, CA, United States

 
Non-invasive coronary angiography is one of the most important goals in cardiovascular imaging and MRI is a promising modality for addressing this critical need. In this work, we present a 3D whole-heart free-breathing coronary MRI technique based on the 3D cones readout trajectory, which enables a high degree of scan time reduction compared to 3D Cartesian encoding and exhibits greater robustness to motion/flow. In addition, 2D navigator images are acquired directly over the heart to compensate for respiratory motion and multiple cardiac phases are resolved to support retrospective selection of the best phase for visualization.

 
1262.   Estimation of Respiratory Tracking Factor between Pulmonary Vein and Right Hemi-Diaphragm For Free-breathing PV LGE 
Mehdi Hedjazi Moghari1, Beth Goddu1, Kraig K Kissinger1, Lois Goepfert1, Warren J Manning1, and Reza Nezafat1
1Dept. of Medicine (Cardiovascular Div.), Beth Israel Deaconess Medical Center, Harvard Medical Sch., Boston, MA, United States

 
In this study, respiratory motion of pulmonary veins (PV) with respect to that of the right-hemi-diaphragm (RHD) is investigated. Tracking factors between PV and RHD’s respiratory motions of 19 subjects are calculated to be 0.45 and shown to be subject-dependent.

 
1263.   Design and Evaluation of an MR Compatible Pneumatic Non-rigid Moving Heart Phantom for Simulating Respiratory and Cardiac Motion 
Doug Stanton1, Neha Dobhal1, Michele Casanova2, Mehdi Hedjazi Moghari2, Ameet Jain1, Robert Manzke1, Warren J Manning2, Chris Hall1, and Reza Nezafat2
1Philips Research, Briarcliff Manor, NY, United States, 2Dept. of Medicine (Cardiovascular Div.), Beth Israel Deaconess Medical Center, Harvard Medical Sch., Boston, MA, United States

 
In this study, we present an MR compatible pneumatic heart phantom that can mimic both respiratory and cardiac motions derived from patient’s information.

 
1264.   Minimization of Imaging Artifacts from Profile Ordering of Randomly Selected ky-kz Lines for Prospective Compressed-Sensing Acqusition in 3D Segmented SSFP and GRE Imaging 
Tamer Ahmed Basha1, Mehmet Akcakaya1, Mehdi H Moghari1, Kraig V Kissinger1, Beth Goddu1, Lois Goepfert1, Warren J Manning1, and Reza Nezafat1
1Dept of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States

 
We investigated using a radial profile ordering scheme of the randomly sampled k-space in 3D compressed-sensing acquisition. Phantom and in vivo cardiac imaging were performed to evaluate this ordering.

 
1265.   Time-resolved Contrast-Enhanced Coronary Vessel Wall Imaging 
Jingsi Xie1,2, Xiaoming Bi3, and Debiao Li1,2
1Northwestern University, Chicago, IL, United States, 2Cedars-Sinai Medical Center, Los Angeles, CA, United States, 3Cardiovascular MR R&D, Siemens Healthcare, Chicago, IL, United States

 
We developed a TI-independent 2D black blood imaging technique on coronary vessel wall during contrast injection by using PS reconstruction. Dynamic quantitative indices such as Ktrans, Vp can be calculated from these measurements.

 
1266.   Diagnostic Accuracy of Different Image Postprocessing Methods for the Detection of Coronary Artery Stenoses by Using Contrast Enhanced Coronary MRA at 3.0T 
Qi Yang1, Kuncheng Li1, Xiangying Du1, Lixin Jin2, Jing An2, Renate Jerecic2, and Debiao Li3
1Radiology, Xuanwu Hospital, Beijing, Beijing, China, People's Republic of, 2Siemens Healthcare, MR Collaboration NE Asia, 3Cedars-Sinai Medical Center and UCLA, Los Angeles, CA

 
Contrast enhanced 3T whole heart coronary MR angiography (CMRA) is a reliable method for the detection and exclusion of hemodynamically significant coronary stenosis and has shown high accuracy in one single center trial. With the improvements in spatial resolution, particularly along the z-axis, it is possible to postprocess whole heart CMRA images by using advanced methods such as MIP, curved MPR, and 3D VRT.

 
1267.   Characterization of Plaque with SWI Approach: Ex vivo Study 
David Muccigrosso1, Adil Bashir1, Dongsi Lu1, and Jie Zheng1
1Washington University School of Medicine, St. Louis, MO, United States

 
Susceptibility weighted imaging (SWI) can be used to image vessel wall and calcification with less flow artifacts and partial volume effect. The study is to explore the role of SWI approach in the characterization of various major plaque components. Plaque phantoms, coronary artery specimens, and endarterectomy carotid artery specimens were investigated using 3D SWI sequence. Phase images show clear differentiation of hemorrhage and calcification. The finding indicates possibility to use SWI technique to correctly segment major plaque components.

 
1268.   Improving Fat Suppression in Radial Coronary MRA using a weighted Golden Ratio Acquisition 
Claudia Prieto1, Rene Botnar1, and Tobias Schaeffter1
1Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom

 
Scan time of coronary MRA can be reduced using radial sampling with long cardiac acquisition windows by exploiting its intrinsic motion insensitivity. However, with this approach, image quality may be hampered due to recovery of epicardial fat signal after a fat-saturation prepulse. Here we propose to use a k-space filtered golden radial acquisition to overcome this problem. Filtering is used to weight selectively the k-space data according to their fat saturation levels while the golden angle approach allows retrospective subject-specific filter adaptation for optimal fat suppression. Significantly improved fat-suppression is shown in a water-fat phantom and right coronary artery images in healthy subjects.

 
1269.   Coronary Vein Imaging is Optimal During the Systolic Rest Period in CRT Patients 
Jonathan Suever1, Pierre Watson2, and John Oshinski1,2
1Biomedical Engineering, Georgia Institute of Technology / Emory University, Atlanta, Georgia, United States, 2Radiology, Emory University School of Medicine, Atlanta, Georgia, United States

 
The objective was to quantify periods of low motion of the coronary veins during the cardiac cycle for planning MR coronary venograms. Patients scheduled for cardiac resynchronization therapy (CRT) and patients with coronary artery disease (CAD) were studied. All CRT patients and 32% of CAD patients (all with EF<35%) had a longer systolic rest period. In 77% of patients, cross-sectional area was larger in systole than diastole. The combination of larger vessel areas during systole and the lengthened systolic rest period in CRT patients suggest that systolic imaging would be preferable for coronary vein imaging in CRT patients.

 
1270.   Accelerated Contrast-Enhanced Whole Heart Coronary MRI Using Low-dimensional-Structure Self-learning and Thresholding (LOST), an Improved Compressed Sensing Reconstruction 
Mehmet Akcakaya*1, Tamer Basha*1, Kraig V. Kissinger1, Beth Goddu1, Lois Goepfert1, Warren J. Manning1, and Reza Nezafat1
1Dept. of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States

 
Use of contrast agents in whole heart coronary MRI is known to increase SNR and CNR. However, to take full advantage of the presence of contrast media, the scan times need to be shortened. In this work, we investigated a prospectively accelerated whole heart contrast-enhanced coronary MRI after a bolus infusion of Gd-BOPTA using low-dimensional-structure self-learning and thresholding (LOST), an improved CS reconstruction.

 
1271.   The Next Step in Self-Navigated Coronary MRI: A Hybrid Approach for Affine Motion Correction 
Davide Piccini1, Arne Littmann2, Hui Xue3, Jens Guehring3, and Michael O. Zenge2
1Pattern Recognition Lab, University of Erlangen-Nuremberg, Erlangen, Germany, 2MR Applications and Workflow Development, Healthcare Sector, Siemens AG, Erlangen, Germany, 3Imaging and Visualization, Siemens Corporate Research, Princeton, NJ, United States

 
Conventional navigator-gated techniques for coronary MRI are limited both in scan-time efficiency and precision. Alternative approaches that derive the positional information of the heart directly from the readouts used for imaging achieve up to 100% efficiency, but are limited to 1D rigid respiratory motion correction. In contrast, image registration allows for a more realistic estimation of the underlying 3D motion, but is less efficient. In this work, a hybrid method that combines 1D self-navigation with registration-based affine motion compensation is presented. This method was implemented for 3D radial whole-heart coronary MRI and was compared with a navigator-gated approach in volunteers.

 
1272.   Flexible phase-encoding in 3D coronary MRA with balanced SSFP 
Ek Tsoon Tan1, Luca Marinelli1, Thomas K Foo1, and Christopher J Hardy1
1GE Global Research, Niskayuna, NY, United States

 
Standard breath-held 3D CMRA uses linear phase-encoding, and is challenging because of variation in patients’ cardiac quiescent period and breath-holding abilities. Flexible phase-encoding allows for acquisition window and breath-hold duration to be flexibly adjusted, and can provide 25-30% reduction in acquisitions due to removal of k-space corner samples. A novel and compact flexible-linear scheme was tested in balanced SSFP CMRA. Compared to linear phase-encoding (14 heart-beats), flexible phase-encoding in vivo provided either reduced acquisition window by 30% (14 heart-beats) or a reduced breath-hold duration (9 heart-beats).

 
1273.   MR detects coronary vessel wall imaging with age in healthy subjects 
Andrew David Scott1,2, Jennifer Keegan1,2, Raad H Mohiaddin1,2, and David Firmin1,2
1Cardiovascular Magnetic Resonance Unit, Imperial College London, London, United Kingdom, 2Cardiovascular Magnetic Resonance Unit, The Royal Brompton and Harefield NHS Foundation Trust, London, United Kingdom

 
Autopsy studies have shown that the coronary vessel wall thickens with age. There is, however, a need for a non-invasive, radiation free technique for assessing the coronary wall in longitudinal studies of disease. Beat-to-beat respiratory motion correction (B2B-RMC) is a highly efficient technique (typically >99% efficient) for respiratory motion correction in MR coronary vessel wall imaging. We studied 21 healthy subjects using dark blood prepared high resolution (0.7x0.7x3.0mm) 3D spiral imaging with B2B-RMC. For the first time using non-invasive imaging, we demonstrate significantly increasing coronary vessel wall thickness and wall/outer wall ratio (W/OW) with age in healthy subjects.

 
1274.   Monitoring statin therapy in atherosclerotic rabbits using USPIO-enhanced MRI and FDG-PET on a new PET/MRI system 
Ahmed Klink1, Steve Davis Dickson1, David Izquierdo1, Jason Bini2, Eric Lancelot3, Jesus Mateo4, Phlippe Robert5, Claire Corot3, and Zahi A Fayad6
1Radiology, Translational and Molecular Imaging Institute, New York, NY, United States, 2Radiology, Translational and Molecular Imaging Institute, New York, 10029, United States, 3Guerbet, Paris, France, 4Epidemiology, Atherothrombosis and Imaging, CNIC, Madrid, Spain, 5Research Department, Guerbet, Paris, France, 6Radiology, Translational and Molecular Imaging Institute, New York, United States

 
Effects of statins on the inflammation/macrophage burden in atherosclerotic rabbits were monitored with PET and USPIO-enhanced MRI on combined PET/MRI system. USPIO-enhanced MRI was achieved using P904, a short circulating USPIO demonstrated to be uptaken by macrophages in the plaque while radioactive labeled glucose (FDG) was used to assess macrophage metabolic activity with PET.

 
1275.   Accuracy of magnetic resonance imaging to identify the coronary artery plaque: a comparative study with intravascular ultrasound 
Yi He1, Zhaoqi Zhang1, Qinyi Dai1, Jing An2, Lixin Jin3, Renate Jerecic3, and Debiao Li4
1Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China, People's Republic of, 2Siemens Mindit Magnetic Resonance, Siemens Healthcare, MR Collaboration NE Asia, Shenzhen, China, People's Republic of, 3Siemens Limited China, Siemens Healthcare, MR Collaboration NE Asia, Shanghai, China, People's Republic of, 4Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, United States

 
This study evaluated the ability of black blood coronary arterial wall MRI to identify the coronary artery plaque, using intravascular ultrasound (IVUS) as the golden standard. The vessel cross-sectional area (CSA), luminal CSA, maximal wall thickness, plaque burden of MRI cross-section coronary wall imaging in 19 patients were compared with IVUS. And It showed a good agreement between IVUS and MRI with regard to extent of wall thickening although MRI overestimated plaque burden and degree of luminal stenosis, which is the difference in spatial resolution between techniques.