- Poster presentation
- Open Access
Left ventricular remodeling following myocardial infarction revealed with a quantitative diffusion MRI tractography framework
© Mekkaoui et al; licensee BioMed Central Ltd. 2012
- Published: 1 February 2012
- Left Ventricle
- Diffusion Tensor Image
- Helix Angle
- Infarct Zone
- Remodel Myocardium
A cardiac-tailored framework for 3D Diffusion Tensor MRI tractography is developed and used to characterize myofiber architecture in normal and remodeled myocardium. We show that myofibers in the subepicardium of the remote infarct zone become less oblique (more circumferential) as the heart dilates and remodels. This fiber realignment may play an important role in the loss of contractile function in the remote zone over time.
Large infarctions cause the left ventricle (LV) to dilate and remodel, ultimately leading to a global decrease in LV function. While the impact of infarction on fiber architecture in the infarct zone is well understood, the impact of remodeling on fiber architecture in the remote zone is not. Diffusion Tensor Imaging (DTI) has contributed greatly to the study of cardiac structure and organization, but the majority of these studies employed 2D datasets [1, 2]. Here we aim to characterize fiber architecture in the remote zone of remodeled hearts using a novel 3D cardiac-tailored diffusion MRI tractography framework that allows fibers in the entire heart to be evaluated as continuous entities.
Excised human (n=5) and sheep (n=5) hearts were studied. Large anteroseptal infarctions were produced in the sheep 3 months prior to imaging. DTI of the hearts was performed on a 3T scanner (Trio, Siemens) using 6 gradient-encoding directions, b-value=2000s/mm2; voxel-size=2x2x2mm3; TR/TE=8430/96ms. Fiber tracking was performed with a fourth-order Runge-Kutta approach. Myofibers were classified by their median helix angle (HA) and limited in length to half the LV circumference. Histograms of fiber HA were used to compare myofiber architecture in normal and remodeled myocardium.
The developed DTI tractographic framework allows myofibers be to classified as continuous entities and shows that fibers in the subepicardium of the remote zone lose their oblique orientation. This microstructural change likely contributes significantly to the loss of function seen in the remote zone over time.
R01 HL093038 (Sosnovik), NCRR P41RR14075 (Martinos Center) and MGH-ECOR (Mekkaoui).
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.