Comparison of a Commercially Available Prostate Segmentation Application to Traditional Prolate and Biproximate Ellipsoid Methods for Prostate Volume Measurement

Rationale and ObjectivesTo compare the a commercially available automatic and manually adjusted segmentation software program (DynaCAD ®) to two ellipsoid volume methods using T2-weighted magnetic resonance imaging (MRI).Material and MethodsThis is a retrospective IRB-approved study of 146 patients randomly selected from 1600 consecutive men referred for T2-weighted MRI. All measurements were performed by a single expert senior radiologist. Total prostate volume was calculated using automatic DynaCAD ® software (RCAD), manually adjusted DynaCAD ® (ACAD), traditional ellipsoid method (TE) and a new alternative biproximate ellipsoid method (BE). Results were assessed with ANOVA and linear regression.ResultsMean volumes for RCAD, ACAD, BE and TE were 61.5, 58.4, 56, and 53.2 respectively. ANOVA showed no difference of the means (p> 0.05.) Linear regression showed a coefficient of determination (r 2) between ACAD and TE of 0.92 and between ACAD and BE of 0.90. Using the planigraphic-based segmented ACAD as the “gold’ standard, RCAD overestimated volume by 5%. TE and BE underestimated prostatic volume by 4% and 9% respectively. ACAD processing time was 4.5 to 9.5 minutes (mean=6.6 min.) compared to 1.5 to 3.0 minutes (mean=2.3 min.) for prolate ellipsoid methods.ConclusionManually adjusted MRI T2-weighted segmentation is likely the most accurate measure of total prostate volume. DynaCAD appears to fulfill that function, but manual adjustment of automatic misregistration of boundaries is necessary. ACAD and RCAD are best applied to research use. Ellipsoid methods are faster, more convenient, nearly as accurate and more practical for clinical use.