Cardiovascular

Tuesday 13 May 2014      10:00 - 11:00

Space 1/Power Poster Theatre & Traditional Poster Hall 
Moderators: Ian Marshall, Ph.D. & Machel Salerno, M.D., Ph.D.

Click on this video icon to view the introductory session.

Steve W Leung¹, Richard Lawless¹, Vincent L Sorrell¹, and Moriel Vandsburger^1
1University of Kentucky, Lexington, Kentucky, United States

The development of myocardial fibrosis significantly heightens the risk of sudden cardiac death. Late gadolinium enhanced (LGE) MRI has become the reference standard for detection of fibrotic tissue, however, multiple high risk patient cohorts are contraindicated to LGE-CMR. We developed a novel fibrosis imaging technique that utilizes magnetization transfer (MT) from fibrotic tissue for completely non-invasive diagnosis of fibrotic remodeling. In this preliminary study, demonstrate excellent correlation of fibrosis as identified with MT-weighted bSSFP MRI with LGE-CMR and measurement of gadolinium partition coefficient.

Ivan Cokic¹, Avinash Kali², Xunzhang Wang², Hsin-Jung Yang², Richard L. Q. Tang², Anees Thajudeen², Michael Shehata², Allen M. Amorn², Enzhao Liu², Brian Stewart³, Nathan Bennett³, Doron Harlev³, Sotirios A. Tsaftaris⁴, Warren M. Jackman⁵, Sumeet S. Chugh², and Rohan Dharmakumar^2
1Cedars-Sinai Medical Center, Los Angeles, CA, United States, ²Cedars-Sinai Medical Center, CA, United States, ³Rhythmia Medical-Boston Scientific, Inc., MA, United States, ⁴Institute for Advanced Studies, Lucca, Italy, ⁵Heart Rhythm Institute, OK, United States

Myocardial infarction can lead to chronic iron deposition that can be accurately quantified with T2* MRI. However, its long-term fate and influence on myocardial electrical properties remain largely unexplored. In this study we used T2* MRI to characterize chronic iron deposition in canines with chronic myocardial infarction in combination with impedance spectroscopy, surface ECG indices and electroanatomical maps to demonstrate that the electrical behavior of infarcted hearts with iron appear to be different from those without iron.

Yongxia Zhou¹, Michael C Langham¹, Erica N Chirico^1,2, Erin K Englund¹, Emile R Mohler III³, Jeremy F Magland¹, Wensheng Guo⁴, and Felix W Wehrli^1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, ²School of Nursing, University of Pennsylvania, Philadelphia, PA, United States,³Medicine, University of Pennsylvania, Philadelphia, PA, United States, ⁴Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA, United States

The purpose was to assess various surrogates of endothelial dysfunction using parameters derived from dynamic MRI sequences. Measures of peripheral vascular reactivity were assessed via dynamic venous oximetry, arterial hyperemia and multi-segment pulse-wave velocity (PWV) of thoracic and abdominal aorta in the form of a single, integrated MR protocol in 132 subjects consisting of young and old smokers and nonsmokers. Our results demonstrate significant aging and smoking effects based on parameters determined from dynamic MRI measures, thereby providing new vascular biomarkers for the effect of age and smoking on vascular endothelial function.

Yu Ding¹, Rizwan Ahmad¹, Ning Jin², and Orlando Simonetti^1
1The Ohio State University, Columbus, OH, United States, ²Siemens Healthcare, Chicago, IL, United States

This study provides a new perspective on the 4-point balanced velocity-encoding technique from the Fourier transform/frequency domain point of view. We show that, from a Fourier encoding point of view, each of the velocity directions is encoded into a sub-band centered on a different frequency by amplitude modulation. Velocity reconstruction is shown to be equivalent to a traditional filter design problem in the Fourier domain. A straight-forward velocity reconstruction algorithm based on a simple Fourier domain filter is described and tested in a volunteer. Comparing to the traditional sliding window reconstruction, the proposed method eliminates artifactual oscillations in the velocity curves.

Choukri Mekkaoui¹, Marcel P Jackowski², Christian T Stoeck³, Aravinda Thiagalingam⁴, William J Kostis⁵, Jeremy N Ruskin⁵, Timothy G Reese⁶, Sebastian Kozerke⁷, and David E Sosnovik^8
1Harvard Medical School - Massachusetts General Hospital, Boston, MA, United States, ²Department of Computer Science, Institute of Mathematics and Statistics, University of São Paulo, São Paulo, Brazil, ³Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland,⁴University of Sydney, Sydney, Australia, ⁵Massachusetts General Hospital, Boston, United States, ⁶Athinoula A Martinos center for Biomedical imaging, Boston, United States, ⁷University and ETH Zurich, Zurich, Switzerland, ⁸Harvard Medical School - Massachusetts General Hospital, Boston, United States

The tractographic propagation angle (PA) is a topographic measure of myocardial fiber architecture. Here, we demonstrate the correlation of PA with late gadolinium enhancement and electroanatomical voltage mapping in the detection of infarcted myocardium (PA>4^o), as well as its ability to delineate regions of heterogeneous scar (4^o≤PA≤10^o) and dense scar (PA>10^o). PA detects infarction and defines the substrate for reentrant ventricular arrhythmias without the need for exogenous contrast agents. PA could become a valuable tool in cardiovascular imaging, especially among patients with renal dysfunction and those at risk of sudden cardiac death.

Eric G. Stinson¹, Joshua D. Trzasko¹, Paul T. Weavers¹, and Stephen J. Riederer^1
1Mayo Clinic, Rochester, Minnesota, United States

Single-echo Dixon-based methods can provide the benefits (improved SNR, subtraction error reduction) of Dixon-based contrast-enhanced MR angiography (CE-MRA) without extending scan time. A theoretical SNR and CNR analysis of single-echo Dixon compared to subtraction CE-MRA was performed and compared to phantom and in vivo results. Single-echo Dixon CE-MRA provides a contrast concentration-dependent SNR and CNR boost of at least 2 over subtraction CE-MRA. At high contrast concentrations (>3-4mmol) Gadolinium-induced susceptibility artifacts can reduce the SNR and CNR of pre-calibrated Dixon CE-MRA. This technique may allow time-resolved CE-MRA with higher SNR and CNR and improved resistance to motion than subtraction-based methods.

Courtney K Morrison¹, Mahdi S Rahimi¹, Kang Wang², James H Holmes², Peter Bannas^3,4, Utaroh Motosugi³, and Frank R Korosec^1,3
1Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, ²Global MR Applications and Workflow, GE Healthcare, Madison, WI, United States, ³Radiology, University of Wisconsin-Madison, Madison, WI, United States, ⁴Radiology, University Hospital Hamburg-Eppendorf, Hamburg, Germany

Conventional contrast-enhanced peripheral MR angiography (MRA) typically uses subtraction-based methods, which are susceptible to misregistration from patient motion and suffer from decreased signal-to-noise ratio (SNR) relative to non-subtractive methods. Previous work has demonstrated the use of non-subtractive contrast-enhanced peripheral MRA at 3.0 T during the steady state and at 1.5 T using a bolus-chase method. This work investigates the clinical feasibility of using a contrast-enhanced, time-resolved, non-subtractive method for MRA at 3.0 T in patients with peripheral vascular disease.

Alejandro Roldán-Alzate¹, Camilo A Campo¹, Kevin M Johnson², Scott B Reeder^1,2, and Oliver Wieben^1,2
1Radiology, University of Wisconsin, Madison, Wisconsin, United States, ²Medical Physics, University of Wisconsin, Madison, Wisconsin, United States

The purpose of this study was to evaluate the repeatability of 4D PC flow measurements in both arteries and veins of the abdominal circulation. 10 subjects, 3 patients with portal hypertension and 7 controls were included in the study. Excellent correlation and low percent difference between repeated measurements within the same day for both arterial and venous circulation demonstrates the repeatability of radial 4D flow MRI for quantifying blood flow in the abdominal circulation. Similarly comparison of day-to-day variation show that radial 4D flow MRI is repeatable for assessing mesenteric hemodynamics in controlled fasting states.

Carla Contaldi¹, Pim van Ooij², Bradley Allen², Julio Garcia², Jeremy Collins², James Carr³, Daniel C. Lee⁴, Brandon Benefield², Lubna Choudhury¹, Michael Markl⁵, Alex J. Barker², and Robert O. Bonow^1
1Department of Medicine – Cardiology, Northwestern University Feinberg School of Medicine, Chicago, IL, Chicago, Illinois, United States, ²Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, Chicago, Illinois, United States, ³Radiology and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, Chicago, Illinois, United States, ⁴Department of Medicine – Cardiology and Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, Chicago, Illinois, United States, ⁵Radiology and Biomedical Engineering, Northwestern University Feinberg School of Medicine, Chicago, IL, Chicago, Illinois, United States

The aim of this study was to characterize obstructive hypertrophic cardiomyopathy (HCM) severity by irreversible energy loss, caused by viscous dissipation, and calculated from 4D Flow MRI velocity fields covering the entire left ventricular outflow tract (LVOT). The difference in energy loss between HCM patients and controls was significant. Energy loss showed a strong correlation with LVOT gradient calculated from 4D Flow MRI and a good correlation with myocardial fibrosis as quantified by extracellular volume fraction by T1 mapping MRI. Elevated energy loss may indicate increased hemodynamic loading and left ventricular remodeling and may be useful in HCM severity assessment.

Marc D Lindley^1,2, Daniel Kim¹, Glen Morrell¹, Marta E Heilbrun¹, Pippa Storey³, Christopher J Hanrahan¹, and Vivian S Lee^1
1UCAIR, Radiology, University of Utah, Salt Lake City, Utah, United States, ²Physics, University of Utah, Salt Lake City, Utah, United States, ³Radiology, New York University, New York, United States

Non-contrast MRA based on subtraction of two FSE acquisitions of the thigh at 3T suffers from signal loss in right femoral common artery due to B1+ inhomogeneities. We propose to recover the signal loss with high-permittivity dielectric padding. In 11 subjects, apparent CNR, normalized B1, and image quality scores verified superior performance with custom-made high-permittivity dielectric padding in comparison with baseline and commercially available dielectric padding. Our study shows that signal loss in right common femoral artery in non-contrast MRA at 3T is recovered with high-permittivity dielectric padding.

Andrew Nicholas Priest¹, Sally Hunter¹, Ilse Joubert¹, Sarah Hilborne¹, David J Bowden¹, Martin John Graves¹, Trevor Baglin², and David John Lomas^1
1Radiology, Addenbrooke's Hospital and University of Cambridge, Cambridge, United Kingdom, ²Haematology, Addenbrooke's Hospital, Cambridge, United Kingdom

Both non-contrast-enhanced MR venography (NCE-MRV) and MR direct thrombus imaging (MR-DTI) can image deep vein thrombosis (DVT). The MR-DTI signal varies with thrombus age. We measured the size and location of a first DVT assessed by NCE-MRV and MR-DTI acquired at three different time-points. The two methods always agreed at the first time-point, within a week of diagnosis, but at later time-points (three and six months) most of the thrombus was not seen on MR-DTI, with only very small bright-signal regions. This may be important for the clinically-important question of distinguishing between acute recurrent thrombus and a residual previous DVT.

Jianing Pang^1,2, Zhaoyang Fan², Reza Arsanjani², Daniel S Berman², and Debiao Li^2,3
1Radiology and Biomedical Engineering, Northwestern University, Chicago, IL, United States, ²Biomedical Imaging Research Institiute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, ³Bioengineering, University of California, Los Angeles, CA, United States

We have demonstrated a fully self-gated 4D whole-heart imaging technique with high isotropic spatial resolution and near 100% imaging efficiency through respiratory motion correction and retrospective cardiac gating. No ECG or diaphragm navigator is needed. The 4D visualization allows one to determine the precise quiescent period retrospectively. Future efforts will be focused on optimizing of the sequence and reconstruction parameters, as well as comparing the dual-mode reconstruction against existing coronary MRA and cine protocols.

Julio Garcia¹, Alex J. Barker¹, Pim van Ooij¹, Susanne Schnell¹, S. Chris Malaisrie², Jeremy Collins¹, James Carr¹, and Michael Markl^1
1Radiology, Northwestern University, Chicago, Illinois, United States, ²Division of Cardiac Surgery, Northwestern University, Chicago, Illinois, United States

Time-resolved 3D PC-MRI data analysis can be time consuming and often relies on the manual placement of 2D analysis planes at user defined vascular regions of interest. The inherent volumetric 3D coverage of the vascular system of interest provided by 4D flow MRI is not fully utilized by analysis based on 2D planes. It was thus the aim of this study to evaluate a novel automated flow distribution analysis based on the evaluation the blood flow velocity distributions in the entire 3D vessel segments to identify hemodynamic 'fingerprints' of different aortic pathologies.

Rita Morisi¹, Rohan Dharmakumar^2,3, and Sotirios A. Tsaftaris^1,4
1IMT Institute for Advanced Studies, Lucca, LU, Italy, ²Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States, ³Medicine, University of California, Los Angeles, California, United States, ⁴Electrical Engineering and Computer Science, Northwestern University, Evanston, Evanston, IL, United States

Cardiac-phase resolved Blood Oxygen-Level-Dependent (CP-BOLD) MRI is a new approach capable of detecting an ongoing ischemia without the need for provocative stress. Current disease assessment relies on segmental analysis and uses only a few cardiac phases of the cine acquisition. It is expected that using all phases can permit pixel-level characterization. This work explores Independent Component Analysis (ICA) for pixel-level ischemia characterization. Using simulated data we demonstrate the potential utility of ICA for overcoming existing limitations in discriminating ischemic territories on the basis of CP-BOLD

Martine Truijman^1,2, Alexandra de Rotte³, Rune Aaslid⁴, Anouk van Dijk^5,6, Madieke Liem⁷, Floris Schreuder^2,8, Robert van Oostenbrugge⁸, Joachim Wildberger¹, Paul Nederkoorn⁷, Jeroen Hendrikse³, Aad van der Lugt⁵, Werner Mess², and Marianne Eline Kooi^1
1Radiology, Maastricht University Medical Center, Maastricht, Netherlands, ²Clinical Neurophysiology, Maastricht University Medical Center, Maastricht, Netherlands, ³Radiology, University Medical Center, Utrecht, Netherlands, ⁴Hemodynamics AG, Bern, Switzerland, ⁵Radiology, Erasmus Medical Center, Rotterdam, Netherlands, ⁶Neurology, Erasmus Medical Center, Rotterdam, Netherlands, ⁷Neurology, Academic Medical Center, Amsterdam, Netherlands, ⁸Neurology, Maastricht University Medical Center, Maastricht, Netherlands

Vulnerable carotid atherosclerotic plaque features, such as intraplaque haemorhage, fibrous cap status and microembolic signals, are frequently studied to identify those patients with an increased risk of a recurrent stroke. The purpose of this study was to investigate the relationship between these MRI and transcranial Doppler ultrasound determined features. The results show no significant difference in MES between patients with intraplaque haemorrhage or thin/ruptured fibrous cap. This indicates that MRI and transcranial Doppler ultrasound provide additive information on plaque vulnerability.