Comparison of Prostate Volume Measured by Transrectal Ultrasonography and MRI with the Real Prostate Volume Measured after Radical Prostatectomy

Jeong, Chang Wook; Lee, Hak Jong; Lee, Sang Eun

Abstract

PURPOSE: The aim of this study was to compare the prostate volume, as measured by transrectal ultrasonography (TRUS) and by MRI, with that of the real prostate volume measured after a radical prostatectomy (RRP).
MATERIALS AND METHODS
This prospective study included 21 clinically localized prostate cancer patients that had undergone a RRP. TRUS prostate volumes were calculated using the prolate ellipsoid volume formula, with the anteroposterior diameter measured from the axial (TRUS_V1) and midsagittal images (TRUS_V2). Two prolate ellipsoid volumes (MRI_EV1 and MRI_EV2) were calculated from the MRI using the same method, and planimetric volume (MRI_PV) with 3D image software. The real prostate volume (Real_V) was measured in a measuring jug within 1 hour after RRP.
RESULTS
The average age and preoperative serum prostate-specific antigen (PSA) were 65.5 years (54-70) and 6.8ng/ml (2.5-17.0), respectively. Mean of Real_V, TRUS_V1 and TRUS_V2 were 40.3ml (21.0-82.0), 42.4ml (23.8-82.2) and 51.4ml (29.1- 87.3), respectively. The mean of MRI_EV1, MRI_EV2 and MRI_PV were 44.2ml (17.9-85.2), 41.0ml (15.7-93.9) and 40.9ml (19.4-83.8), respectively. In a paired sample test, the correlation coefficients (R) for all methods used were over 0.8. In a Student's t-test (paired), the MRI_PV (p=0.620), MRI_ EV2 (p=0.703) and TRUS_V1 (p= 0.099) showed no significant differences compared to the Real_V. The linear regression models of this three methods were y=1.025x 0.268, y=0.946x 2.979 and y=1.046x 0.381, respectively.
CONCLUSIONS
Between the TRUS prolate ellipsoid volumes, the TRUS_V1 was shown to be superior to the TRUS_V2. In the MRI, the MRI_EV2 was more accurate than the MRI_EV1. However the MRI_PV was the most accurate method. The TRUS_V1, MRI_EV2 could be used instead of the MRI_PV in general clinical settings.