Tumor Volumes in Choroidal Melanoma: Agreement Between Three-Dimensional Ultrasound and Two Mathematical Models

PurposeTo determine the degree of agreement between 2 mathematical models and 3-dimensional ultrasonography (3DUS) in estimating choroidal melanoma tumor volumes.DesignReliability analysis.MethodsTumor measurements estimated by 2 mathematical models (designated Formula 1 and Formula 2) were compared to those obtained by 3DUS in 45 consecutive patients with primary choroidal melanoma to determine the percentage agreement between the models and 3DUS.ResultsBoth formulas tended to overestimate the tumor volume. Overall, the mean volume differences between 3DUS and Formula 1 and between 3DUS and Formula 2, respectively, were 51.7 mm3 (95% confidence interval [CI], 187.6 to 84.3) and 23.8 mm3 (95% CI, 122.5 to 74.8). Excluding mushroom-shaped tumors, the mean volume differences were 52.0 mm3 (95% CI, 194.9 to 91.0) and 23.0 mm3 (95% CI, 127.0 to 81.0), respectively. In mushroom-shaped tumors, mean volume differences were 49.9 mm3 (95% CI, 135.7 to 35.9) and 29.3 mm3 (95% CI, 87.6 to 29.0), respectively.ConclusionsThe agreement between these mathematical models and the measured 3DUS volume was high. The data obtained in this study show that both formulas provide a simple, fast, and accurate method of estimating tumor volumes in the clinical setting, suggesting that these models could be used as a reliable and inexpensive alternative to time-consuming procedures such as 3DUS or magnetic resonance imaging. The accurate tumor volume values provided by these formulas may help to provide more reliable estimates of tumor regression or regrowth following globe-preserving treatment of choroidal melanomas, and may be a valuable prognostic indicator.