Suspected Local Recurrence after Radical Prostatectomy: Endorectal Coil MR Imaging

Abstract

PURPOSE: To evaluate endorectal coil magnetic resonance (MR) imaging in the depiction of local recurrence after radical prostatectomy. MATERIALS AND METHODS: Endorectal MR images were reviewed retrospectively in 82 patients who underwent prostatectomy. The interval between prostatectomy and MR imaging ranged between 0.5 and 13.0 years (mean, 3.25 years). Local recurrence was considered present if there was no evidence of distant metastases and there was a positive biopsy result, subsequent reduction in prostate-specific antigen (PSA) level after radiation therapy of the pelvis, or serial MR imaging findings of increased tumor size. Local recurrence on MR images was assessed for location, size, signal intensity, and invasion of adjacent structures. All images were reviewed independently by two readers who were blinded to clinical information. RESULTS: Thirty-four of 82 patients did not meet inclusion criteria. Forty-one of 48 remaining patients had clinically documented local recurrence, which MR imaging depicted in 39 of 41 (95%) patients. Seven of 48 patients had no evidence of local or distant metastases, and none had positive MR imaging findings. Sensitivity of MR imaging was 95%, and specificity was 100%. Local recurrences were penanastomotic in 12 (29%) patients and retrovesical in 17 (40%), within retained seminal vesicles in nine (22%), and at anterior or lateral surgical margins in four (9%). All local recurrences were hyperintense to adjacent pelvic muscles on T2-weighted MR images. The mean diameter of tumors was 1.4 cm (range, 0.8-4.5 cm). PSA levels at MR imaging in patients with clinically proved recurrences ranged from undetectable to 10 ng/ mL (mean, 2.18 ng/mL). CONCLUSION: MR imaging depicts a high proportion of local recurrence after prostatectomy. The authors propose incorporation of endorectal coil MR imaging in the diagnostic paradigm of patients who have undergone prostatectomy and are suspected of having local recurrence. © RSNA, 2004.