Histological validation of myocardial microstructure obtained from diffusion tensor magnetic resonance imaging

TLDR

Diffusion tensor MRI offers a rapid, artifact‑free method to map myocardial fiber organization, yet its quantitative validation against histology has been lacking. The study compared fiber orientations measured by diffusion tensor MRI and histology at identical sites in two perfused rabbit hearts. The two modalities produced statistically similar orientations, differing by an average of 12°, comparable to the 10° uncertainty of histology, and imaging of seven hearts revealed laminar organization beyond individual myofibers.

Abstract

Diffusion tensor magnetic resonance imaging (MRI) is a possible new means of elucidating the anatomic structure of the myocardium. It enjoys several advantages over traditional histological approaches, including the ability to rapidly measure fiber organization in isolated, perfused, arrested hearts, thereby avoiding fixation and sectioning of artifacts. However, quantitative validation of this MRI method has been lacking. Here, fiber orientations estimated in the same locations in the same heart using both diffusion tensor MRI and histology are compared in a total of two perfused rabbit hearts. Fiber orientations were statistically similar for both methods and differed on average by 12° at any single location. This is similar to the 10° uncertainty in fiber orientation achieved with histology. In addition, imaging studies performed in a total of seven hearts support a level of organization beyond the myofiber, the recently described laminar organization of the ventricular myocardium.