QUANTITATIVE ASSESSMENT OF SONOGRAPHIC IMAGE ECHOGENICITY BY TRANSMISSION DENSITOMETRY - FETAL LIVER MODEL

A mathematical method is proposed to compare density values of differe nt sonographs of the same tissue. Two transformations were needed: (1) calibration of the gray scale according to the maximal range of scann ing for a given tissue, and (2) comparison of the effect of two time-c ompensated gains on the difference in density and standardizing this e ffect to an arbitrary gain. To verify these relationships, 12 fetal li vers were scanned at 38 weeks' gestation, at three different gains cor responding to the optimal gain and to the minimal and maximal gains th at allowed a clear image to be obtained. After the mathematical transf ormations, the initially completely different densities were nearly id entical (t-test: P = 0.9998; Wilcoxon test: P > 0.5; Pearson's R = 0.8 933). This method permits an accurate quantitative assessment of the e chogenicity of any parenchymatous organ.