Arunark Kolipaka¹, Kiaran McGee¹, Shivani Aggarwal¹, Nandan Anavekar¹, Armando Manduca¹, Richard Ehman¹, and Philip Araoz^1
1Mayo Clinic, Rochester, Minnesota, United States

Hypertrophic cardiomyopathy (HOCM) is a genetic cardiac disease and is thought to increase myocardial stiffness. Recently, MR elastography (MRE) has been adapted to measure stiffness in the myocardium. The purpose of this study was to demonstrate the feasibility of using MRE to identify changes in the stiffness of LV in HOCM’s when compared to normals. MRE was performed on 18 normal volunteers and 2 HOCM patients. During end-systole an increased stiffness with a mean value of 14.5 kPa was found as compared to normals with a mean value of 5.6 kPa.

Heiko Tzschätzsch¹, Thomas Elgeti¹, Sebastian Hirsch¹, Thoralf Niendorf², Jürgen Braun³, and Ingolf Sack^1
1Department of Radiology, Charité University Medicine, Berlin, Germany, ²Berlin Ultrahigh Field Facility, Charité University Medicine, Berlin, Germany, ³Institute of Medical Informatics, Charité University Medicine, Berlin, Germany

The variation of myocardial elasticity enables the heart to circulate blood through the cardiovascular system. Thus, measurement of heart elasticity by elastography techniques may play a key role in the diagnosis of cardiac dysfunction. This paper presents a novel approach in cardiac MR elastography. The method relies on shear waves with amplitudes in the order of the in-plane resolution of vibration-synchronized MRI. Wall oscillations in the heart can directly be monitored in magnitude images without the need of specialized motion encoding gradients and phase unwrapping algorithms.

Lukas Winter¹, Christof Thalhammer¹, Matthias Dieringer^1,2, Celal Özerdem¹, Jan Rieger¹, Fabian Hezel¹, Wolfgang Renz³, and Thoralf Niendorf^1,2
1Berlin Ultrahigh-Field Facility, Max Delbrueck Center for Molecular Medicine, Berlin, Germany, ²Experimental and Clinical Research Center (ECRC), Charité Campus Buch, Humboldt-University, Berlin, Germany, ³Siemens AG, Erlangen, Germany

Multichannel transmit and receive coil arrays give promising results to overcome the challenges towards clinical cardiac imaging at ultrahigh field strengths. The comparison of 4-, 8- and 16-channel cardiac coils shows a higher SNR, CNR as well as image homogeneity while moving towards a higher number of TX/RX elements. Clinically relevant short axis and four chamber view cardiac 2D CINE FLASH, tag band prepared 2D CINE FLASH and 2D CINE SSFP images were acquired and compared.

Subashini Srinivasan^1,2, Peng Hu², Kraig V. Kissinger², Beth Goddu², Lois Geopfert², Ehud J. Schmidt³, Sebastian Kozerke¹, and Reza Nezafat^2
1Institute of Biomedical Engineering, ETH, Zurich, Switzerland, ²Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, ³Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States

2D black blood imaging of the heart is commonly used in the assessment of myocardial wall anatomy, cardiac masses and other pathologic conditions. In this study, we describe a free-breathing whole heart 3D black-blood imaging using MSDE preparation pulse. Images with T1 weighted turbo spin echo, spoiled gradient echo, and balanced steady state free precession in axial and short axis planes were acquired from 7 healthy adult subjects. Excellent suppression of blood and clear delineation of the cardiac chamber walls and papillary muscle was observed with all the imaging sequences but with additional undesired signal loss in the myocardium (14%-27%).

Bastiaan J van Nierop¹, Elza D van Deel², Dirk J Duncker², Gustav J Strijkers¹, and Klaas Nicolay^1
1Biomedical NMR, department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands, ²Department of Cardiology, Thoraxcenter, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands

In this study the temporal evolution of cardiac function was studied in C57BL/6 mice with a mild constriction of the aorta, resulting in compensated hypertrophy, and in mice with a severe constriction of the aorta. Only the mice with a severe constriction showed a progressive increase in left ventricular mass accompanied by a progressive decline of left and right ventricular ejection fraction, as well as lung edema. The different disease progression between both animal models opens unique opportunities to study interventions, and to study different aspects of myocardial hypertrophy during the transition from compensated hypertrophy towards overt HF.

Shuning Huang¹, Choukri Mekkaoui¹, Miloslav Polasek¹, Howard H. Chen¹, Ruopeng Wang¹, Soeun Ngoy², Ronglih Liao², Van J Wedeen¹, Guangping Dai¹, Peter Caravan¹, and David E Sosnovik^1,3
1Martinos Center for Biomedical Imaging, Mass General Hospital, Charlestown, MA, United States, ²Cardiology, Brigham and Woman's Hospital, Boston, MA, United States,³Cardiology, Mass General Hospital, Boston, MA, United States

The transition from adaptive hypertrophy to heart failure is poorly understood. Here, we use molecular MRI of a collagen-binding gadolinium chelate and in-vivo diffusion tensor MRI (DTI) of the mouse heart to characterize the response of the left ventricle to pressure overload. We show that pressure overload results in significant amounts of fibrosis and circumferential realignment of myofibers well before the overt transition to diastolic heart failure.

Herve Lombaert^1,2, Jean-Marc Peyrat³, Stanislas Rapacchi⁴, Laurent Fanton⁵, Herve Delingette², Nicholas Ayache², and Pierre Croisille^4
1Ecole Polytechnique, Montreal, QC, Canada, ²Asclepios, INRIA, Sophia-Antipolis, France, ³Siemens Molecular Imaging, Oxford, United Kingdom, ⁴Creatis-LRMN, HCL, Lyon, France, ⁵Institut Universitaire de Médecine Légale, Lyon, France

A human statistical atlas of the cardiac fiber architecture is constructed from ex-vivo diffusion tensor images and is based on a set of 10 normal human hearts. To the best of our knowledge, this is the first time that such study has been conducted with human data. We have developed a semi-automated method where only minimal interactions are required for the segmentation of the myocardium, and where the registrations are fully automated via symmetric log domain diffeomorphic demons. The results on the variability of human cardiac fibers concur with studies on other mammals. The cardiac fiber orientation is indeed much more consistent across our population than the orientation of the cardiac laminar sheets.

Choukri Mekkaoui¹, Shuning Huang¹, Guangping Dai¹, Timothy G Reese¹, Marcel P Jackowski², and David Sosnovik^3
1Radiology, Harvard Medical School, Massachusetts General Hospital, Martinos Center For Biomedical Imaging, Charlestown, MA, United States, ²Computer Science, University of São Paulo, Institute of Mathematics and Statistics, São Paulo, Brazil, ³Cardiology, Harvard Medical School, Massachusetts General Hospital, Martinos Center For Biomedical Imaging, Charlestown, MA, United States

The supertoroid-based representation of cardiac diffusion tensor MRI (DT-MRI) has previously been shown to enhance the three-dimensional perception of myocardial tissue structure and organization. In this work, the quantification of DT-MRI data using the supertoroidal model is performed in vivo for the first time. The toroidal indices TV and TC revealed that diffusivity and anisotropy values are homogeneous and highly reproducible in the myocardium in vivo. Changes in diffusivity in infarcted myocardium are detected with greater sensitivity with TV than MD. The supertoroidal formalism thus holds significant promise for the analysis of myocardial microstructure with DT-MRI.

Christian Torben Stoeck¹, Nicolas Toussaint², Peter Boesiger¹, Philip G Batchelor², and Sebastian Kozerke^1,2
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, ²Imaging Sciences, King's College London, London, United Kingdom

Cardiac DTI faces major challenges due to underlying physiological motion such as breathing and the heart beat. Therefore the timing of diffusion encoding is essential for the success of diffusion weighted imaging in the heart. In this Study we introduce a dynamic timing scout sequence and investigate time windows during the cardiac cycle usable for DTI. Imaging is possible during the upslope of circumferential contraction and symmetry point of rotational motion. It appears that the optimal timing window is independent of the subject’s heart rate.

Xiaodong Zhong¹, Lauren B Gibberman², Andrew D Gilliam³, Craig H Meyer^2,4, Brent A French⁴, and Frederick H Epstein^2,4
1MR R&D Collaborations, Siemens Healthcare, Atlanta, GA, United States, ²Radiology Department, University of Virginia, Charlottesville, VA, United States, ³Andrew D. Gilliam Consulting, Providence, RI, United States, ⁴Biomedical Engineering Department, University of Virginia, Charlottesville, VA, United States

MRI of myocardial mechanics in mice enables the investigation of the roles of individual genes and experimental therapies in cardiac function. While two-dimensional tagging, HARP, and DENSE have previously been demonstrated in the mouse heart, myocardial mechanics are more comprehensively assessed using three-dimensional (3D) methods. In this study, 3D cine DENSE acquisition and analysis methods for mice imaging were developed, and were evaluated in normal mice. A comprehensive assessment of 3D myocardial mechanics in mice can be performed with a scan time of less than 25 minutes and a segmentation time of about an hour, followed by automatic post-processing.