Assessment of the risk of positive surgical margins with pelvic phased-array magnetic resonance imaging in patients with clinically localized prostate cancer: A prospective study

Objectives. We assessed magnetic resonance imaging (MRI) performance in the prediction of positive surgical margins (PSMs) before radical prostatectom y in a prospective study correlating the MRI results and pathologic finding s. Methods. Between January 1995 and December 1999, 176 patients (mean age 64. 2 years, range 49 to 75), with localized prostate cancer (49 with Stage T1 and 127 with Stage T2) underwent preoperative MRI with a pelvic phased-arra y coil (Tesla-1, Siemens) at a mean interval of 35 days after randomized tr ansrectal biopsies. The mean preoperative prostate-specific antigen level w as 10.9 ng/mL (range 1.2 to 39). The MRI studies and specimen analysis were performed by one radiologist unaware of the clinical and biopsy findings a nd by one pathologist, respectively. Multivariate analysis was performed to compare the predictive value of MRI staging, prostate-specific antigen val ue, and preoperative Gleason score to identify the PSM rate. Results. Of the 176 patients, 131 (74%) had Stage T2 disease by MRI and 45 (26%) Stage T3 disease by MRI. Pathologic staging showed 103 with pT2 and 7 3 with pT3. Overall, the PSM rate of the series was 18%. The PSM rate was 1 3.7% and 31% for patients with T2 and T3 disease by MRI, respectively. For the T3 MRI cases, the PSM rate was 2.32-fold higher. MRI staging, like the prostate-specific antigen value, was a predictive factor of PSMs (P = 0.05) . Conclusions. The results of this study show that preoperative MRI staging w ith the phased-array coil may be helpful in predicting the PSM risk in radi cal prostatectomy candidates with clinically localized prostate cancer. URO LOGY 58: 228-232, 2001. (C) 2001, Elsevier Science Inc.