Diagnostic A-Scan of Choroidal Tumors: Comparison of Quantified Parameters

To compare quantified ultrasonographic A-scan parameters of common choroidal tumors.

Consecutive patients with a clinical diagnosis of choroidal melanoma (n = 100), choroidal nevus (n = 30), choroidal metastasis (n = 10), and circumscribed choroidal hemangioma (n = 10) were included in this study. Ultrasonographic A-scans (8 MHz, 1,550 m/s, tissue sensitivity = 67 dB) were performed by standard techniques. Using a custom made MATLAB® script, four quantifiable A-scan parameters: tumor height (mm), number of internal reflectivity peaks (numerical value), median internal reflectivity (%), and angle κ (°) were obtained for all (n = 150) tumors.

The mean number of internal reflectivity peaks for choroidal nevus, choroidal metastasis, and circumscribed choroidal hemangioma was 3.1, 5.1, and 4.0, respectively. The median internal reflectivity for choroidal melanoma varied from 21.5 to 99.5% (mean = 76.4%). The median internal reflectivity was ≥65% in all choroidal nevus (100%), choroidal metastasis (100%), and circumscribed choroidal hemangioma (100%), and majority of the choroidal melanoma (78%).

The quantified A-scan patterns of common choroidal tumors were significantly influenced by the tumor height. Other than median internal reflectivity of < 65%, which seems to distinguish choroidal melanoma from other tumors (choroidal nevus, choroidal metastasis, and circumscribed choroidal hemangioma), there were no specific diagnostic patterns.