PROSTATE CARCINOMA - MR-IMAGING FINDINGS AFTER CRYOSURGERY

PURPOSE: To determine the morphologic changes in the prostate gland af ter cryosurgery and to assess the value of magnetic resonance (MR) ima ging in detecting residual tumor. MATERIALS AND METHODS: Twenty-seven patients with prostate carcinoma underwent endorectal MR imaging after cryosurgery. Eighteen patients also underwent MR imaging before cryos urgery. MR findings were correlated with posttreatment clinical data, prostate-specific antigen level, and biopsy results. RESULTS: Mean pro state volume had decreased by 52% in patients examined 8 weeks or more after cryosurgery. Zonal differentiation was lost in 22 of 27 patient s (81%). Areas of intraprostatic necrosis were identified in 14 of 27 patients (52%). A thick capsule enveloped the gland and neurovascular bundles in 24 of 27 patients (89%). Osteonecrosis of the symphysis pub is was seen in six of 27 patients (22%). Positive and negative predict ive values for MR assessment of recurrent tumor were 44% and 73%, resp ectively. CONCLUSION: Cryosurgery-induced changes in the prostate glan d preclude reliable detection of residual prostate carcinoma at MR ima ging.