Diffusion Biomarkers in Chronic Myocardial Infarction

Abstract

Cardiac diffusion tensor magnetic resonance imaging (cDTI) allows estimating the aggregate cardiomyocyte architecture in healthy subjects and its remodeling as a result of cardiac disease. In this study, cDTI was used to quantify microstructural changes occurring in swine (N = 7) six to ten weeks after myocardial infarction. Each heart was extracted and imaged ex vivo with $1\,\mathrm {mm}$ isotropic spatial resolution. Microstructural changes were quantified in the border zone and infarct region by comparing diffusion tensor invariants – fractional anisotropy (FA), mode, and mean diffusivity (MD) – radial diffusivity, and diffusion tensor eigenvalues with the corresponding values in the remote myocardium. MD and radial diffusivity increased in the infarct and border regions with respect to the remote myocardium ($p< 0.01$). In contrast, FA and mode decreased in the infarct and border regions ($p< 0.01$). Diffusion tensor eigenvalues also increased in the infarct and border regions, with a larger increase in the secondary and tertiary eigenvalues.

This work was supported by NIH/NHLBI K25-HL135408 to LEP, AHA 20POST35210644 to KM, and the University of Central Florida. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Funders.

Appendix

Mean diffusivity (MD) and Radial diffusivity (Rd) data are reported separately for each subject in Fig. 5. As also evident in Fig. 4, there is a significant variability across subjects, in part as a function of infarct size.

Fig. 5.

Grouped box plots overlaid on top of corresponding Mean diffusivity (MD) and Radial diffusivity (Rd) data points (cross and circular markers) in the infarct (left, purple), border (center, yellow), and remote (right, blue) myocardial regions for each subject. Cross markers represent data points 1.5 IQR above Q3 or below Q1. (Color figure online)