ISMRM 21st Annual Meeting & Exhibition 20-26 April 2013 Salt Lake City, Utah, USA

Cardiac Microstructure & Function
Wednesday 24 April 2013
Room 255 EF  13:30 - 15:30 Moderators: Daniel B. Ennis, David N. Firmin

13:30 0479.   Time-Resolved In Vivo Cardiac Diffusion Tensor MRI of the Human Heart
Sonia Nielles-Vallespin1,2, Pedro Ferreira3, Peter David Gatehouse1, Jennifer Keegan1, Ranil de Silva3, Tevfik Ismail1, Andrew Scott1, Timothy G. Reese4, Choukri Meekaoui4, Peter Speier5, Thorsten Feiweier6, David E. Sosnovik4, Andrew E. Arai2, and David N. Firmin1
1Royal Brompton Hospital, Imperial College, London, London, United Kingdom, 2National Heart Lung and Blood Institue (NHLBI), National Institues of Health (NIH), DHHS, Bethesda, MD, United States, 3Royal Brompton Hospital, London, London, United Kingdom, 4Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 5Siemens AG Healthcare Sector, Erlangen, Germany, 6Siemens AG, Erlangen, Germany

Zonal-excitation and partial-Fourier were combined to speed up a diffusion-weighted stimulated-echo single-shot-EPI technique to acquire in-vivo cardiac Diffusion Tensor Imaging (cDTI) at any time point over the entire cardiac cycle. 5 healthy volunteers were scanned. Mean-diffusivity, fractional-anisotropy, helix-angle and superquadric glyph maps were produced. We show here for the first time in-vivo cDTI images of the human heart over the entire cardiac cycle. The rotation of the diffusion tensor as the heart contracts and expands can be observed. This technique promises to provide novel insights into the structure-function relationships in the heart, and its changes in the presence of disease.

13:42 0480.   
High-Resolution Single-Shot DTI of the in-vivo Human Heart Using Asymmetric Diffusion Encoding
Christian T. Stoeck1, Constantin von Deuster1,2, Nicolas Toussaint2, and Sebastian Kozerke1,2
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 2Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom

A single-shot DTI-SE approach employing asymmetric (ASY) Stejskal-Tanner diffusion encoding is presented addressing limitations of STEAM acquisition for diffusion tensor imaging of the in-vivo heart. It is shown that high-resolution multi-slice cardiac DTI data can be obtained permitting 3D tensor reconstructions of the entire left ventricle. The scheme holds potential for application in patients as data acquisition is performed during free-breathing of the subject without requiring any breathhold or guided breathing patterns.

13:54 0481.   Diffusion MRI Tractography of the Developing Human Fetal Heart
Choukri Mekkaoui1, Prashob Porayette2, Marcel Parolin Jackowski3, William Kostis4, Guangping Dai5, Stephen Sanders6, and David E. Sosnovik4
1Harvard Medical School - Massachusetts General Hospital - Athinoula A Martinos center for Biomedical, Boston, MA, United States, 2Cardiology, Children's Hospital Boston, Boston, MA, United States, 3University of São Paulo, São Paulo, São Paulo, Brazil, 4Harvard Medical School - Massachusetts General Hospital - Athinoula A Martinos center for Biomedical, Charlestown, MA, United States, 5Massachusetts General Hospital, Charlestown, MA, United States, 6Children's Hospital Boston, Boston, MA, United States

There is increased interest in the use of stem cells and tissue scaffolds to regenerate lost myocardium. Diffusion MRI tractography of the developing human fetal heart may provide valuable insights to optimize the regeneration of myocardium in the adult heart. We show that myofiber anisotropy develops in the human fetal heart well after it has looped and started to contract. This suggests that implanted stem cells may also be able to endogenously align themselves to form fiber tracts and subsequently sheets. The use of scaffolds therefore may not be a prerequisite for successful cell therapy.

14:06 0482.   Quantitative Analysis of Cardiac Motion Effects on in vivo Diffusion Tensor Parameters -permission withheld
Hongjiang Wei1, Magalie Viallon1,2, Benedicte M.A. Delattre1, Lihui Wang1, Vinay M. Pai3, Han Wen3, Pierre Croisille1,4, and Yuemin Zhu1
1CREATIS, CNRS (UMR 5220), INSERM (U1044),INSA Lyon,University of Lyon, Lyon, France, 2Department of Radiology,University Hospitals of Geneva, Geneva, Switzerland, 3Imaging Physics Lab, BBC/NHLBI/NIH, Bethesda, Maryland 20892, United States, 4Jean-Monnet University, Saint-Etienne, France

Cardiac motion is a crucial problem in in vivo diffusion tensor imaging (DTI) of the human heart. Its effects of on diffusion tensor parameters of the human heart have not been well established. Recently, an efficient method was proposed that acquires cardiac diffusion weighted (DW) images at different time points of the cardiac cycle and removes motion-induced signal loss using PCA filtering and temporal MIP techniques (PCATMIP). Meanwhile, polarized light imaging (PLI) provides us the ground-truth of the heart fiber architecture, and DENSE technique offers us higher spatial resolution 3D displacement fields of the human heart. These different imaging possibilities have led us to investigate a multimodal approach to quantitatively analyze the effects of cardiac motion on diffusion tensor parameters.

14:18 0483.   Diffusion Tensor MRI Revealed Developmental Changes of Cardiomyocyte Architecture in Pig Hearts
Junjie Chen1, Lei Zhang2, John S. Allen3, Lingzhi Hu4, Shelton D. Caruthers3, Gregory M. Lanza3, and Samuel A. Wickline3
1Internal Medicine, Washington University In Saint Louis, Saint Louis, MO, United States, 2Washington University School of Medicine, Saint Louis, mo, United States, 3Internal Medicine, Washington University School of Medicine, Saint Louis, mo, United States, 4Physics, Washington University School of Medicine, Saint Louis, mo, United States

The new-born heart undergoes substantial structural and functional changes to accommodate the rapid switching from fetal to neonatal circulation immediately after birth. We hypothesized that three dimensional cardiomyocyte architecture might be required to adapt rapidly to accommodate programmed perinatal changes of cardiac function. Our results showed that the helical architecture of left ventricular cardiomyocytes was developed as early as mid-gestation period, After birth, cardiomyocytes architecture in the right ventricular free-wall and septum changed rapidly, illustrating the plasticity of cardiomyocyte architecture in response to the new demands of the left and right ventricular function.

14:30 0484.   
Cardiac Laminae Structure Dynamics from in-vivo Diffusion Tensor Imaging
Nicolas Toussaint1, Christian T. Stoeck2, Tobias Schaeffter1, Maxime Sermesant3, and Sebastian Kozerke1,2
1Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom, 2Institute for Biomedical Engineering, University and ETH, Zurich, Switzerland, 3Asclepios Research Group, INRIA, Sophia-Antipolis, France

The laminae arrangement within the left ventricle is believed to strongly determine the tissue shearing that allows the muscle contraction. In this work we demonstrate that in-vivo DTI is capable of detecting discrepancies between diastolic and systolic laminae organization that agrees with previously reported histological studies.

14:42 0485.   
Improved Cardiac Motion Self-Gating
Fei Han1, Stanislas Rapacchi1, and Peng Hu2
1Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, United States, 2Department of Radiological Sciences, University of California Los Angeles, Los Angeles, CA, United States

A new cardiac self-gating method in which the self-gating signal is derived from repeatedly acquired non-phase-encoded k-space centerline instead of the center k-space point used in conventional self-gating method. Principle Component Analysis is used for processing the acquired self-gating signal and triggers are generated by detecting peaks on the processed signal. Experiment results shows that the motion signal provided by the proposed method is free of the distortion and artifact usually seen in conventional self-gating method and the detected triggers are with high reliability and accuracy when using ECG as reference.

14:54 0486.   
Characterising Global and Regional Myocardial Motion Patterns for the Whole Cardiac Cycle Using Retrogated Spiral Phase Velocity Mapping
Robin Simpson1,2, Jennifer Keegan1,2, and David N. Firmin1,2
1Imperial College London, England, United Kingdom, 2Cardiovascular BRU, Royal Brompton Hospital, London, United Kingdom

A novel sequence for measuring myocardial velocities with high spatial and temporal resolution using spiral k-space trajectories is presented. The use of retrospective cardiac gating allows the analysis of the entire cardiac cycle, including atrial systole. Results from ten healhty volunteers show consistent patterns of motion characterised by average peak and TTP velocities throughout the cardiac cycle. Complex regional motion patterns can be easily assessed using newly developed 2D colour plots.

15:06 0487.   
Myocardial Tagging in the Polar Coordinate System; Initial Clinical Results
Sarah N. Khan1, Abbas N. Moghaddam2, Razieh Kaveh2, Ali Nsair3, Mona Bhatia1, and J. Paul Finn4
1Diagnostic Cardiovascular Imaging, Department of Radiology, UCLA, Los Angeles, CA, United States, 2Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran, 3Department of Cardiology, UCLA, Los Angeles, CA, United States, 4Diagnostic Cardiovascular Imaging, Department of Radiology, University of California Los Angeles, Los Angeles, CA, United States

We compared grid, radial and circular tagging patterns for assessment of radial and circumferential myocardial displacement in 10 volunteers and 18 patients (10 congenital heart disease (CHD) and 8 cardiomyopathy (CM)). Images were scored subjectively and processed quantitatively for circumferential and radial strain. Polar tagging was easier to interpret (ave 3.6) than grid tagging (ave 2.9). Tag quality and confidence in strain assessment was similar among the three tag groups. Patients with CM had diminished radial strain rate (1.19±0.26 sec-1) when compared to volunteers (1.64±0.61 sec-1). We conclude that polar tagging has advantages for the visual and quantitative assessment of myocardial strain.

15:18 0488.   
Left Ventricular Twist and Systolic Twist-Per-Volume Slope in Patients with Mitral Regurgitation
Meral L. Reyhan1,2, Ming Li3, Hyun Grace Kim1, Himanshu Gupta4,5, Steven G. Lloyd4,5, Louis J. Dell'Italia4,5, Thomas Stewart Denney3, and Daniel B. Ennis1,2
1Department of Radiological Sciences, University of California Los Angeles, Los Angeles, CA, United States, 2Biomedical Physics Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States, 3Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, United States, 4Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States, 5Birmingham VA Medical Center, Birmingham, AL, United States

Primary mitral regurgitation (MR) is a common valvular disorder that foments left ventricular (LV) dysfunction. LV twist is a quantitative imaging biomarker for LV dysfunction and was studied in normal subjects and patients with moderate and severe MR. Compared to normal subjects peak LV twist was decreased in moderate and severe MR. No differences were detected in CL-shear angle between the groups. Peak systolic twist-per-volume slope was significantly different for all pairwise comparisons and was decreased in moderate MR and further decreased in severe MR compared to normal subjects. Peak systolic twist-per-volume slope may possibly serve as sensitive imaging biomarker of LV dysfunction in patients with primary MR.