Investigation on the structure of ventricular mass using magnetic resonance diffusion tensor imaging

The 3-dimensional arrangement of the ventricular mass remains controversial. In this study, we used magnetic resonance diffusion tensor imaging (MRDTI) in an attempt to determine whether the ventricular mass is arranged in the form of a helical ventricular myocardial band (HVMB) and what the geometrical features of the HVMB are in postmortem pig hearts.

Ten pig hearts were harvested from the slaughterhouse, and their whole-body MR images were obtained. The data were obtained via DTI by single-shot echo planar imaging and sensitivity encoding. The pig hearts were scanned with single-shot echo planar imaging and sensitivity-encoding scans (TE/TRZ78.5/10000 ms) with diffusion-sensitized gradients (b = 800 s/mm2) along 6 directions. Color-coded imaging and fiber-tracking techniques were used to investigate the arrangement of the fibers of ventricular mass on a GE Healthcare Advantage Workstation (Microsoft Windows).

Color-coded images showed that the ventricular wall in each section was uniformly divided into 3 layers (subendocardial, middle, and subepicardial) in all samples. Fiber tracking showed that the subendocardial layer ran obliquely from base to apex, turned a circle, and transformed into the middle layer at the apex, and then ran obliquely upward. The ventricular mass was arranged in the form of double-helical coils. The crossing angle between subendocardial layer and middle layer was nearly vertical.

Results of our investigation with MRDTI support the theory of Torrent-Guasp et al that the ventricular mass is arranged in the form of an HVMB.