DETECTION OF LOCALLY RECURRENT PROSTATE-CANCER AFTER CRYOSURGERY - EVALUATION BY TRANSRECTAL ULTRASOUND, MAGNETIC-RESONANCE-IMAGING, AND 3-DIMENSIONAL PROTON MAGNETIC-RESONANCE SPECTROSCOPY

Objectives. To assess and compare the clinical usefulness of transrect al ultrasound (TRUS), magnetic resonance imaging (MRI), and three-dime nsional proton magnetic resonance spectroscopic imaging (3-D MRSI) in detecting local recurrence of carcinoma of the prostate (CaP) in patie nts with detectable prostate-specific antigen (PSA) levels after cryos urgery. Methods. In a prospective study, 25 patients who had undergone cryosurgery as primary treatment for Cap underwent endorectal MRI and 3-D MRSI, followed by TRUS-guided prostate biopsy. At the time of stu dy, 20 patients had detectable PSA; the remaining 5 patients sewed as controls. All patients had random sextant and guided prostate biopsy f or correlation with imaging and MR spectroscopic findings. Results. In patients with detectable PSA, MRSI identified, location-for-location, all foci of Cap and benign prostatic tissue that were detected by pro state biopsy. MRSI identified more sites with CaP than did prostate bi opsy, indicating a larger volume of cancer. In 2 patients with detecta ble PSA and negative prostate biopsy, MRSI identified ii voxels with v iable prostatic tissue. in patients with undetectable PSA, both MRSI a nd prostate biopsy showed necrosis. Ultrasound and MRI were very poor tools for identifying recurrent cancer and differentiating between via ble and necrotic prostate tissue. Conclusions. 3-D MRSI is superior to TRUS and MRI in differentiating among CaP, BPH, and necrosis when loc al recurrence after cryosurgery is suspected. By providing chemical ma pping of the prostate in contiguous voxels, the addition of spectrosco py to endorectal MRI increases the sensitivity for detection of local recurrence.