Anisotropy of the backscatter coefficient of formalin-fixed ovine myocardium.

The objective of this study was to measure the backscatter coefficient of formalin-fixed myocardial tissue as a function of angle of insonification relative to the myocardial fiber direction. Backscatter measurements were performed on eight cylindrical formalin-fixed lamb myocardial specimens and compensated for attenuation and diffraction effects to determine the backscatter coefficient. The backscatter coefficient at 5 MHz was found to be maximum for insonification perpendicular to the predominant myofiber orientation and minimum for parallel insonification, with values of (17+/-14) and (1.2+/-0.7) x 10(-4) cm(-1) sr(-1) (mean+/-standard deviation), respectively.