Journal of Ultrasound in Medicine, Vol 12, Issue 10 567-571, Copyright © 1993 by American Institute of Ultrasound in Medicine
Quantitative assessment of sonographic image echogenicity by transmission densitometry: fetal liver model
I. Blickstein
Department of Obstetrics and Gynecology, Kaplan Hospital, Rehovot, Israel.
A mathematical method is proposed to compare density values of different
sonographs of the same tissue. Two transformations were needed: (1)
calibration of the gray scale according to the maximal range of scanning
for a given tissue, and (2) comparison of the effect of two
time-compensated gains on the difference in density and standardizing this
effect to an arbitrary gain. To verify these relationships, 12 fetal livers
were scanned at 38 weeks' gestation, at three different gains corresponding
to the optimal gain and to the minimal and maximal gains that allowed a
clear image to be obtained. After the mathematical transformations, the
initially completely different densities were nearly identical (t-test: P =
0.9998; Wilcoxon test: P > 0.5; Pearson's R = 0.8933). This method
permits an accurate quantitative assessment of the echogenicity of any
parenchymatous organ.
