Li Feng^1,2, Jian Xu³, Leon Axel¹, Daniel Sodickson¹, and Ricardo Otazo^1
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.

Daniel A. Auger¹, Xiaodong Zhong², Frederick H. Epstein³, and Bruce S. Spottiswoode^1,4
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.

Christian Torben Stoeck¹, Nicolas Toussaint², Peter Boesiger¹, and Sebastian Kozerke^1,2
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.

Choukri Mekkaoui¹, Sonia Nielles-Vallespin², Peter Gatehouse², Marcel P Jackowski³, David Firmin², and David E Sosnovik^4
1Harvard Medical School, Boston, MA, United States, ²Royal Brompton Hospital, ³University of São 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.

Avinash Kali^1,2, Andreas Kumar³, Dror Berel⁴, Veronica L M Rundell⁵, Richard Tang⁴, James Min⁴, and Rohan Dharmakumar^4,5
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.

Rahul Rustogi¹, Mauricio Galizia¹, Jeremy Collins¹, Darshit Thakrar¹, Asad Usman¹, Bernd Jung², Daniela Foell³, Saurabh Shah⁴, James Carr¹, and Michael Markl^1
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.

Kieren G Hollingsworth¹, Tracey A Willis², Ben J Dixon¹, Hanns Lochmuller², Kate Bushby², John Bourke², Guy A MacGowan², Andrew M Blamire¹, and Volker Straub^2
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.

Wouter Oosterlinck¹, Tom Dresselaers², Vincent Geldhof¹, Marijke Pellens¹, Stefan Janssens¹, Uwe Himmelreich², and Paul Herijgers^1
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

Bernd Jung¹, Daniela Foell², Corinna Lang², David Ziupa², Gerlind Franke², Stefanie Perez Feliz², Michael Brunner², Gideon Koren³, Manfred Zehender², and Katja E Odening^2
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.

Jun Lu¹, Mingming Li², Beau Pontre³, Stephen Pickup⁴, Anothny Phillips², and Garth JS Cooper^2
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.