Prostate MRI to Evaluate Extra-Prostatic Disease: A Single Center Analysis

Abstract

Introduction: To examine the use of prostate magnetic resonance imaging (MRI) for staging after a new diagnosis of prostate cancer in our hospital system. There are no universally accepted recommendations to guide the use of MRI for staging purposes. In practice, prostate MRI is used to help distinguish T2 and T3 cancer. Prostate MRI is a modality that could aid in the triage of patients to radical prostatectomy or non-surgical treatments via accurate identification of organ-confined disease. Materials and Methods:We performed a retrospective review of prostate cancer patients who underwent staging MRI with 1.5T MRI with endorectal (ER) coil. We compared patient characteristics in patients who underwent surgery and those who did not, and used pathology reports from prostatectomy samples to calculate the negative predictive value (NPV) for extra-capsular extension (ECE) and seminal vesicle invasion (SVI). Results: We found that patients who underwent radical prostatectomy were younger, had lower Gleason scores, and had lower PSA values at diagnosis than patients who were not treated surgically. We calculated a NPV of 93.7% for SVI and 69.5% for ECE. We found variation in rates of accurate identification of T3 prostate cancer across the seven radiologists who interpreted MRI images in our study. Conclusions: 1.5T MRI with ER coil has a high NPV for SVI and a lower NPV for ECE. The utilization of 3TMRI may enable practitioners to more confidently rule out ECE. Future studies will be necessary to generate guidelines for use of MRI in prostate cancer staging.