Detecting ultrasonographic hollowness in small choroidal melanocytic tumors using 10 MHz and 20 MHz ultrasonography: a comparative study.

Background: The purpose of this work was to compare the detection of ultrasonographic hollowness (UH), as a risk sign for evolution from small choroidal melanocytic tumors (SCMT) to uveal melanoma (UM), between conventional ultrasonography (standardized 8 MHz ultrasonography and B-mode 10 MHz ultrasonography) and high-resolution 20 MHz ultrasonography.

Methods: Fifty SCMTs from 50 eyes were included in this work. In all cases, ultrasonographic studies were performed using: 8 MHz standardized A-mode, 10 MHz B-mode, and posterior pole 20 MHz B-mode. Comparison between the presence and the absence of UH were carried out between the ultrasonographic images.

Results: There were no statistically significant differences between the SCMT dimensions obtained using the 8-10 and 20 MHz techniques. UH was detected in 12 and 20 cases by means of ten and 20 MHz probes respectively. The difference between these proportions was statistically different from zero (McNemar test, p-value = 0.008). Cases without UH by 20 MHz have lower height values than cases with UH. However, these differences were not found by 10 MHz ultrasonography. By receiver operating characteristic (ROC) study, specificity was better by 20 MHz than 10 MHz ultrasonography when the value of tumor height as marker for UH was studied.

Conclusions: UH is easier to detect by 20 MHz than by 10 MHz ultrasonography. This ultrasonographic sign appears to be correlated with the height of the tumor. Thus, we believe UH estimation by 20 MHz ultrasonography could be used as a significant predictive factor for SCMT growth.