Room 255 EF

13:30 - 15:30

Moderators:

Daniel B. Ennis, David N. Firmin

Sonia Nielles-Vallespin^1,2, 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. Firmin^1
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.

Christian T. Stoeck¹, Constantin von Deuster^1,2, Nicolas Toussaint², and Sebastian Kozerke^1,2
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.

Choukri Mekkaoui¹, Prashob Porayette², Marcel Parolin Jackowski³, William Kostis⁴, Guangping Dai⁵, Stephen Sanders⁶, and David E. Sosnovik^4
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.

Hongjiang Wei¹, Magalie Viallon^1,2, Benedicte M.A. Delattre¹, Lihui Wang¹, Vinay M. Pai³, Han Wen³, Pierre Croisille^1,4, and Yuemin Zhu^1
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.

Junjie Chen¹, Lei Zhang², John S. Allen³, Lingzhi Hu⁴, Shelton D. Caruthers³, Gregory M. Lanza³, and Samuel A. Wickline^3
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.

Nicolas Toussaint¹, Christian T. Stoeck², Tobias Schaeffter¹, Maxime Sermesant³, and Sebastian Kozerke^1,2
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.

Fei Han¹, Stanislas Rapacchi¹, and Peng Hu^2
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.

Robin Simpson^1,2, Jennifer Keegan^1,2, and David N. Firmin^1,2
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.

Sarah N. Khan¹, Abbas N. Moghaddam², Razieh Kaveh², Ali Nsair³, Mona Bhatia¹, and J. Paul Finn^4
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.

Meral L. Reyhan^1,2, Ming Li³, Hyun Grace Kim¹, Himanshu Gupta^4,5, Steven G. Lloyd^4,5, Louis J. Dell'Italia^4,5, Thomas Stewart Denney³, and Daniel B. Ennis^1,2
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.