CV Function
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Tuesday 8 May 2012
Room 219-220  10:00 - 12:00 Moderators: Sebastian Kozerke, Michael Salerno

10:00 0225.   
High Spatial and Temporal Resolution 2D Real Time and 3D Whole-Heart Cardiac Cine MRI Using Compressed Sensing and Parallel Imaging with Golden Angle Radial Trajectory
Li Feng1,2, Jian Xu3, Leon Axel1, Daniel Sodickson1, and Ricardo Otazo1
1Radiology, New York University School of Medicine, New York, New York, United States, 2Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York, United States, 3Siemens Medical Solutions, New York, New York, United States

Cardiac cine MRI is valuable for imaging myocardial function. High spatial and temporal resolutions are desirable to improve diagnostic utility. In this study, we propose a joint reconstruction algorithm that combines compressed sensing and parallel imaging for highly undersampled golden angle radial k-space acquisitions, to enable 2D real-time and 3D whole-heart cardiac cine MRI with previously inaccessible spatial and temporal resolution. The technique allows reconstruction of the same data set with different temporal resolutions. We demonstrate the feasibility of 2D real-time cine imaging with 11ms temporal resolution and 3D whole-heart cine imaging with an acquisition window of 22.4ms per partition.

10:12 0226.   
Mapping regional right ventricular myocardial strain using 3D cine DENSE MRI
Daniel A. Auger1, Xiaodong Zhong2, Frederick H. Epstein3, and Bruce S. Spottiswoode1,4
1MRC/UCT Medical Imaging Research Unit, University of Cape Town, Cape Town, Western Cape, South Africa, 2MR R&D Collaborations, Siemens Healthcare, Atlanta, Georgia, United States, 3Departments of Radiology and Biomedical Engineering, University of Virginia, Charlottesville, Virginia, United States, 4Division of Radiology, University of Stellenbosch, Cape Town, Western Cape, South Africa

The mechanics of the right ventricle (RV) are notoriously difficult to quantify because of the RV’s thin wall and irregular geometry. However, the recently developed spiral 3D cine DENSE MRI technique is well suited to imaging the RV. This work presents model-free techniques to study the myocardial mechanics of the RV at a high spatial resolution using spiral 3D cine DENSE MRI. These involve tailored post-processing algorithms for mid-wall tissue tracking and strain estimation. The RV is subdivided into four regions according to anatomical landmarks, and the temporal evolution of strain is assessed for a group of normal volunteers.

10:24 0227.   
Dual heart-phase cardiac DTI using Local-look STEAM
Christian Torben Stoeck1, Nicolas Toussaint2, Peter Boesiger1, and Sebastian Kozerke1,2
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 2Imaging Sciences, King's College London, London, United Kingdom

Analysis of diffusion tensor imaging of the myocardium reveals insight into cardiac mechanics. Previous studies investigated myocardial architecture at different states of cardiac contraction in ex-vivo animal hearts or by interpreting the strain tensor. In this study we present an initial direct comparison of systolic vs. diastolic fiber architecture of the in-vivo human heart based on diffusion weighted images acquired at both time points during the cardiac cycle using a local-look STEAM sequence.

10:36 0228.   In Vivo Assessment of Myofiber Dynamics in the Human Heart Using Supertoroidal Analysis of Diffusion Tensor MRI
Choukri Mekkaoui1, Sonia Nielles-Vallespin2, Peter Gatehouse2, Marcel P Jackowski3, David Firmin2, and David E Sosnovik4
1Harvard Medical School, Boston, MA, United States, 2Royal Brompton Hospital, 3University of Săo Paulo, 4Harvard Medical School - Massachusetts General Hospital

Supertoroidal analysis provides a novel formalism to analyze diffusion tensor MRI (DTI) data in the heart. Here, for the first time, we use supertoroids to analyze in vivo DTI datasets from normal human volunteers. We show that the volumetric nature of supertroidal-derived indices makes them extremely sensitive to changes in the diffusion eigenvalues. The orientation of the toroids (primary diffusion eigenvector) changes little as the myocardium contracts, except in the subepicardium. However, toroidal volume and curvature both decrease significantly as the myocardium contracts, reflecting a reduction in diffusion anisotropy in the myocardium during systole.

10:48 0229.   
Temporal features of edema in acute myocardial infarction: T2 maps vs T2-STIR
Avinash Kali1,2, Andreas Kumar3, Dror Berel4, Veronica L M Rundell5, Richard Tang4, James Min4, and Rohan Dharmakumar4,5
1University of California, Los Angeles, CA, United States, 2Cedars-Sinai Medical Center, Los Angeles, California, United States, 3Laval University, Laval, QC, Canada, 4Cedars-Sinai Medical Center, Los Angeles, CA, United States, 5Northwestern University, Chicago, IL, United States

The temporal features of myocardial edema during ischemia and post-reperfusion were studied using T2 maps and T2-STIR images. Relative edema, infarct volumes and myocardial salvage were measured at baseline, during ischemia and one and 8 weeks post-reperfusion. Relative to baseline, a significant edema volume was apparent during ischemia, but was markedly elevated and remained constant up to one-week post-reperfusion, and regressed to baseline levels by week 8. Ischemic edema volume was not indicative of post-reperfusion edema volume. Myocardial salvage was constant for one-week post-reperfusion. T2 maps and T2-STIR images appear to provide equivalent information on myocardial edema and salvage.

11:00 0230.   
Myocardial Velocity and T2 Mapping Reveals Changes in LV Structure and Function after Heart Transplantation
Rahul Rustogi1, Mauricio Galizia1, Jeremy Collins1, Darshit Thakrar1, Asad Usman1, Bernd Jung2, Daniela Foell3, Saurabh Shah4, James Carr1, and Michael Markl1
1Radiology and Biomedical Engineering, Northwestern University Feinberg School of Medicine, Chicago, IL, United States, 2Medical Physics, Freiburg University Medical Center, Freiburg, Germany, 3Cardiology, Freiburg University Medical Center, Freiburg, Germany, 4Siemens Healthcare, Chicago, United States

In a pilot study using a small cohort of post cardiac transplantation patients, we demonstrate the ability of novel non-invasive myocardial velocity mapping and T2 mapping to reveal underlying changes in myocardial structure and function. T2 maps assess myocardial edema while myocardial velocity maps detect changes in diastolic relaxation. Post transplant patients showed significant heterogeneity in distribution of T2 relaxation times and reduced peak radial and long axis velocities compared with normal control subjects. Very good agreement was found between independent readers indicating myocardial velocity mapping to be a highly reproducible method for assessing diastolic dysfunction.

11:12 0231.   Subepicardial dysfunction leads to global left ventricular systolic impairment in patients with limb girdle muscular dystrophy 2I permission withheld
Kieren G Hollingsworth1, Tracey A Willis2, Ben J Dixon1, Hanns Lochmuller2, Kate Bushby2, John Bourke2, Guy A MacGowan2, Andrew M Blamire1, and Volker Straub2
1Newcastle Magnetic Resonance Centre, Newcastle University, Newcastle upon Tyne, Tyne and Wear, United Kingdom, 2Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, Tyne and Wear, United Kingdom

The assessment of cardiac involvement is important in Limb Girdle Muscular Dystrophy 2I, and the mechanisms of cardiac disease in this disease remain to be understood. For the first time, this study combines the techniques of MR cine imaging, MR tagged imaging and MR spectroscopy to assess a large group (n=11) of British patients. As a group, peak cardiac torsion and ejection fraction are significantly reduced in LGMD2I, and the deficit in these two measures is strongly correlated. The relationship between circumferential strain and cardiac torsion suggests subepicardial dysfunction, distinct from previous results on Duchenne muscular dystrophy.

11:24 0232.   Myocardial tagging reveals a distinct regional contractility pattern after Ischemic Postconditioning in Mice
Wouter Oosterlinck1, Tom Dresselaers2, Vincent Geldhof1, Marijke Pellens1, Stefan Janssens1, Uwe Himmelreich2, and Paul Herijgers1
1Cardiovascular Diseases, KU Leuven, Leuven, Belgium, 2Medical Diagnostic Sciences, Biomedical NMR-Unit/MoSAIC, KU Leuven, Leuven, Belgium

We studied ischemia reperfusion and Ischemic Postconditioning in mice. Follow up included non invasive cMRI and myocardial tagging and invasive pressure conductance analysis after 1 and 10 weeks. We studied global and regional contractility changes and evaluated the effect of Ischemic Postconditioning at long term. The cardioprotective effect of IPostC, evidenced after 1 week , is sustained and protects against adverse LV remodeling. Myocardial tagging reveals an improved contractility pattern at both postischemic and remote areas

11:36 0233.   Correlation between Spatial Differences in Action Potential Duration and Myocardial Dysfunction in Transgenic LQT2 Rabbits
Bernd Jung1, Daniela Foell2, Corinna Lang2, David Ziupa2, Gerlind Franke2, Stefanie Perez Feliz2, Michael Brunner2, Gideon Koren3, Manfred Zehender2, and Katja E Odening2
1Radiology, Medical Physics, University Medical Center, Freiburg, Germany, 2Cardiology, University Medical Center, Freiburg, Germany, 3Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Providence, United States

Transgenic LQT2 rabbits and wildtype controls were subjected to in vivo phase contrast MRI in a 1.5T MR-system to assess regional myocardial velocities in the LV (AHA 16-segment model). The same rabbits’ hearts were subsequently Langendorff-perfused and subjected to ex vivo epicardial monophasic action potential measurements to assess APD in the corresponding segments. Prolongation of cardiac repolarization and increased dispersion of APD lead to a globally and regionally impaired systolic and diastolic function in transgenic LQT2 rabbits. Moreover, regional APDs correlate with regional peak diastolic velocities indicating that Long-QT syndrome is not purely an electrical but rather an electromechanical disorder.

11:48 0234.   SSAT inducer as a potential treatment for obesity-related heart failure
Jun Lu1, Mingming Li2, Beau Pontre3, Stephen Pickup4, Anothny Phillips2, and Garth JS Cooper2
1Faculty of Health & Environmental Sciences, Auckland University of Technology, Auckland, North Island, New Zealand, 2School of Biological Sciences, University of Auckland, Auckland, New Zealand, 3Centre for Advanced MRI, University of Auckland, Auckland, New Zealand, 4Dept of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States

This project uses High-Field MRI to study cardiac function and body fat composition of obese mice and the effects of the treatment by diethylnorspermidine, a potent inducer of spermidine/spermine acetyltransferase.