Introduction
Advances in MRI techniques has generated interest in its ability to discriminate between benign and malignant prostate tissue. MP-MRIs are reported with a PI-RADS score. This is a likert score, which determines the likelihood of a lesion being malignant. We performed a retrospective analysis to determine if multiparametric-MRI can be used to identify patients in whom TRUS biopsies can be safely avoided.
Methods
We performed a retrospective review of all patients who were investigated for a raised PSA between September 2015-July 2016 in three London Hospital- The Royal London, Newham University Hospital and St Barts Hospital. All patients underwent a 1.5 Tesla MP-MRI pior to a Transrectal Ultrasound guided Biopsy of their Prostate gland. We noted patient age, PSA level, Prostate volume (calculated by MRI), PSA density, ethnicity, histology and the PI-RADS score on the MP-MRI of the Prostate.
Results
511 patients underwent MP-MRI (prior to a TRUS biopsy of the prostate) over the course of 18 Months in three London Hospitals. The mean age of included patients was 65 years old. A total of 254 prostate cancers were diagnosed.
170 patients were reported to have PIRADS 1-3 lesions. Of these 56 patients (33%) were found to have prostate cancer. The mean Gleason score was 7 (Gleason Score Ranging from 6 to 10).
Furthermore, in 18 patients with histologically proven bilateral prostate cancer, MRI missed cancer in a contralateral lobe.
341 patients were reported to have PIRADS 4/5. 179 were found to have prostate cancer (52%).
The Positive Predictor Value of MP-MRI was found to be 52.5% and the Negative Predictor Value was 67%.
Conclusion
Mp-MRI can miss clinically significant prostate cancers and therefore a normal MRI (PI-RADS 1-3) cannot be used to guide decision to biopsy in patients with an elevated PSA.