Evaluation of 3 T pelvic MRI imaging in prostate cancer patients receiving post-prostatectomy IMRT

Purpose: The purpose of the study was to evaluate the utility of a 3 T pelvic magnetic resonance imaging (MRI) in detecting a local recurrence in post-prostatectomy prostate cancer patients prior to receiving adjuvant or salvage intensity-modulated radiation therapy (IMRT). Methods: Ninety prostate cancer patients status post-prostatectomy with rising prostate-specific antigen (PSA) had a 3 T pelvic MRI prior to IMRT. The following variables were analyzed for predicting positive findings on MRI: initial presenting and initial post-op PSA, PSA at the time of imaging, PSA velocity, surgical margins, Gleason score, pathological stage, pre-RT digital rectal examination, and type of surgical prostatectomy. Results: The only significant variable predictive of a positive MRI was positive margins. Specifically, 15 of 46 (33 %) patients with positive margins had a positive MRI, while 5 of 44 (11 %) patients with negative margins had a positive MRI. In the MRI positive group, the location of the positive findings on MRI corresponded with the pathology report in 9 of 12 (75 %) cases. Conclusion: Post-prostatectomy patients with pathologic positive margins are three times more likely to have positive findings on a 3 T MRI.