Evaluation of prostate volume by transrectal ultrasonography for use in a brachytherapy program

Objectives. To evaluate two methods of measuring the prostate volume using transrectal ultrasonography. The measurements were performed in vivo at pre planning and again preoperatively in connection with brachytherapy. The acc urate measurement of the prostate volume is important in a brachytherapy pr ogram for treatment planning. Methods. A total of 43 patients with biopsy-proven prostate cancer underwen t prospective determination of the prostate volume, by one physician, using transrectal ultrasonography. Volume calculations were made at the preplann ing and preoperative settings, both by a hand-held rectal probe using the p rolate ellipsoid formula and by a mounted probe in a stepping device using the planimetric method. Results. The coefficient of variation between the preplanning and preoperat ive prostate volumes with the probe holder was less than 3% compared with t he hand-held probe, which was greater than 10%. The difference between the median values at the preplanning and preoperative settings by serial planim etry was 2.5 cm(3) (range 0.2 to 9.4). The difference in the median volumes between the preplanning and preoperative ellipsoid calculations was 6.7 cm (3) (range 0.3 to 38.7). The difference between the median values with the ellipsoid volume was significant (P < 0.001). The Pearson correlation coeff icient for all values using the planimetric method was 0.92 versus 0.58 for the ellipsoid method. The correlation coefficient was significantly greate r for the planimetric method (P < 0.001). Conclusions. On the basis of these data, planimetric prostate volume determ ination, by a single ultrasonographer, is an accurate and reproducible meth od with applicability to a brachytherapy program. (C) 2001, Elsevier Scienc e Inc.