PROSTATE-CANCER - METABOLIC RESPONSE TO CRYOSURGERY AS DETECTED WITH 3D H-1 MR SPECTROSCOPIC IMAGING

PURPOSE: To determine, in patients with prostate cancer treated with c ryosurgery, whether levels of choline and citrate measured at magnetic resonance (MR) spectroscopy can help discriminate regions of residual tumor from other prostatic tissues and necrosis. MATERIALS AND METHOD S: Combined MR imaging and three-dimensional proton spectroscopic imag ing were performed in 25 patients (mean age, 69 years) with prostate c ancer who underwent cryosurgery. Volume imaging and spectroscopic data were analytically corrected for the reception profile of the endorect al and pelvic phased-array coils. Spectral data were aligned with the MR imaging data and compared with serum prostate-specific antigen leve ls and biopsy results. RESULTS: Histologically confirmed necrotic tiss ue (432 voxels) did not demonstrate any observable choline or citrate. The (choline + creatine)/citrate values in regions of histologically confirmed benign prostatic hyperplasia (0.61 +/- 0.21 [standard deviat ion], 52 voxels) and cancer (2.4 +/- 1.0, 65 voxels) after cryosurgery were not statistically significantly different from those before ther apy but were statistically significantly different from the ratio in n ecrotic tissue and from each other. The (choline + creatine)/citrate i mages thresholded and overlaid in color on T2-weighted images yielded an estimate of the spatial extent of prostate cancer and benign prosta tic hyperplasia. CONCLUSION: Volume MR imaging with MR spectroscopic i maging provided a noninvasive assessment of the presence and location of residual cancer after unsuccessful therapy and helped identify succ essful cryosurgery in patients who still had an elevated prostate-spec ific antigen level.