In-gantry MRI guided prostate biopsy diagnosis of prostatitis and its relationship with PIRADS V.2 based score

Introduction: The recent literature has focussed predominantly on prostate cancer detection which has been revolutionized by multiparametric magnetic resonance imaging (mpMRI). Due to an overlap of features, prostatitis may mimic prostate cancer on MRI, especially in patients with chronic prostatitis. We retrospectively analysed our in-gantry MRI-guided biopsy (MRGB) results to determine incidental detection rate of prostatitis in Prostate Imaging Reporting and Data System (PIRADS) 3, 4 and 5 foci reported on diagnostic MRI of the prostate. Methods: About 137 patients underwent in-gantry MRGB for lesions with PIRADS score of 3 or above. All the biopsies were performed utilizing the dynaTRIM™ system (Invio Inc, Germany) on a three-tesla MRI scanner (Ingenia 3.0T, Philips, Netherlands) by a Radiologist and a Urologist. Results: We biopsied 228 lesions in 137 patients. There were 55 lesions that returned positive for prostate cancer with a Gleason Score of 3 + 3 = 6 or above. There were 62 lesions that showed inflammation. The distribution of these lesions was 3 (5%) in the central zone, 32 (52%) in the transitional zone and 27 (43%) in the peripheral zone. Inflammation was found in 36 (58%) PIRADS 3 lesions, 24 (39%) PIRADS 4 lesions and 2 (3%) PIRADS 5 lesions on pre biopsy MRI evaluation. Conclusion: In our series, biopsies which showed inflammation had a radiological appearance on mpMRI more likely of a PIRADS 3 or 4 lesions with only 3% of PIRADS 5 biopsies showing inflammation. This would suggest that a higher PIRADS score can more reliably differentiate between prostate cancer and prostatitis.