Regional variation in the measured apparent ultrasonic backscatter of mid-gestational fetal pig hearts.

The goal of this study was to characterize and compare regional backscatter properties of fetal hearts through measurements of the apparent integrated backscatter. Sixteen excised, formalin-fixed fetal pig hearts, representing an estimated 53 to 63 days of gestation, were investigated. Spatially localized measurements of integrated backscatter from these specimens were acquired using a 50 MHz single-element transducer. The apparent integrated backscatter measurements demonstrate different patterns of backscatter from the myocardium of the right ventricle compared with that of the left ventricle. These backscatter measurements appear to be consistent with the anisotropy of the fiber orientation observed in histologic assessment of the same specimens. For each of the 16 hearts, the apparent integrated backscatter from the right ventricular myocardium was larger than that from the left ventricular myocardium, exhibiting mean apparent backscatter values of -35.9 +/- 2.0 dB and -40.1 +/- 1.9 dB (mean +/- standard deviation; n = 16; p < 0.001), respectively. This study suggests that the intrinsic ultrasonic properties of the left and right ventricular myocardium are distinct in fetal pig hearts at mid-gestation.