The Correlation of 3D DT-MRI Fiber Disruption with Structural and Mechanical Degeneration in Porcine Myocardium

Abstract

Evaluation of structural parameters following a myocardial infarction (MI) is important to assess left ventricular function and remodeling. In this study, we assessed the capability of 3D diffusion tensor magnetic resonance imaging (DT-MRI) to assess tissue degeneration shortly after an MI using a porcine model of infarction. Two days after an induced infarction, hearts were explanted and immediately scanned by a 3T MRI scanner with a diffusion tensor imaging protocol. 3D fiber tracks and clustering models were generated from the diffusion-weighted imaging data. We found in a normal explanted heart that DT-MRI fibers showed a multilayered helical structure, with fiber architecture and fiber density reflecting the integrity of muscle fibers. For infarcted heart explants, we observed either a lack of fibers or disruption of fibers in the infarcted regions. Contours of the disrupted DT-MRI fibers were found to be consistent with the infarcted regions. Both histological and mechanical analysis of the infarcted hearts suggested DT-MRI fiber disruption correlated with altered microstructure and tissue mechanics. The ability of 3D DT-MRI to accurately distinguish viable myocardium from dead myocardium only 2 days post infarct without the use of radioisotopes or ionotropic agents makes it a promising approach to evaluate cardiac damage early post-MI.

Estimating passive mechanical properties in a myocardial infarction using MRI and finite element simulations

“…At that time point, the infarct stiffness was isotropic in the control case, but showed increased longitudinal stiffness in the treated case. Zhang et al (Zhang et al 2010) performed diffusion tensor magnetic resonance imaging (DTMRI) and equibiaxial testing on pig hearts 2 days after infarction. In this study, infarcts were generated in the lateral wall and apex of the LV, as well as in the lateral wall of the RV.…”

Quantitative analysis of brain microstructure following mild blunt and blast trauma

“…An in-house three-dimensional fiber tracking model simulated the physical arrangement of axonal fibers (Zhang et al, 2003;Zhang et al, 2004;Correia et al, 2008;Tate et al, 2010;Zhang et al, 2010). Integral curves were created using the major eigenvector field of the diffusion tensor field (Basser et al, 2000).…”

“…Conversely, diffusion tensor imaging (DTI) provides enhanced visualization of tissue microstructure (Sundgren et al, Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jbiomech www.JBiomech.com 2004) such as spinal cord Ozanne et al, 2007), myocardium (Wu et al, 2007;Zhang et al, 2010), and skeletal muscle (Heemskerk et al, 2007;Lansdown et al, 2007). DTI has also been utilized in the brain to assess the integrity of white matter fiber tracts (MacDonald et al, 2007a,b).…”

A remodelling metric for angular fibre distributions and its application to diseased carotid bifurcations

“…Many types of cardiovascular tissues have had their fibre distributions assessed by polarising light microscopy and electron microscopy (Finlay et al 1998;Rowe et al 2003;Canham and Finlay 2004;Tower and Tranquillo 2001). An increase in resolution in imaging modalities, such as diffusion tensor magnetic resonance imaging, may provide in vivo applications; ex vivo studies to date have determined fibre architectures in the myocardium (Wu et al 2007;Zhang et al 2010), aorta (Flamini et al 2010) and articular cartilage (Pierce et al 2010).…”