QUANTITATIVE COMPARISON OF 2 DISTINCT ECHOGENIC STRUCTURES APPEARING ON THE SAME IMAGE USING GAIN-ASSISTED DENSITOMETRIC EVALUATION OF SONOGRAMS (GADES)

Gain-assisted densitometric evaluation of sonograms with two distinct echogenic structures appearing on each image was performed to establis h if their density-gain setting curves have similar inclinations. We u sed the breast model (n = 67) in which hyperechoic masses were compare d to the surrounding hypoechoic tissue at the optimal gain (Gopt) and at Gopt + 5. Both structures had significantly different film-correcte d densities and showed a linear decline of density as the system gain increased from Gopt - 5 to Gopt + 5. The least squares regression line s were almost parallel. The density-gain unit decrease from Gopt - 5 t o Gopt was not different, but the decrease from Gopt to Gopt + 5 reach ed statistical significance. The data suggest that skewed values are t heoretically possible in comparing two distinct echogenic structures. However, within the gain intervals used in GADES, these differences ar e negligible and comparisons are as accurate as with the assessment of a single echogenic structure.