Introduction: We aimed to evaluate whether PIRADS 3 lesions in multiparametric MRI (mpMRI) represent a significant risk of prostate cancer (PCa) in a real-world setting of different referring radiologic institutes.
Materials and methods: Between May 2015 and October 2017, a total of 408 patients were referred to our clinic for MRI-ultrasound fusion targeted biopsy of the prostate (FusPbx) due to suspected prostate cancer. In all patients, preoperatively an mpMRI of the prostate was performed by altogether 62 different radiologic institutes. Prostate lesions were classified according to the PIRADS system. A PIRADS 3 lesion was diagnosed in 41 patients. FusPbx was performed transrectally using a Philips EPIQ 7 (Philips Medical Systems, Bothell, WA) scanner with plane wise fusion of ultrasound and MRI image data. In addition to FusPbx in each patient a randomized 12-core transrectal ultrasound guided biopsy (USPbx) was performed.
Results: Mean PSA Level was 9.5 ng/ml (range: 1- 26 ng/ml), mean patients age was 66.1 years (48.6- 80.4). In 11/41 patients (26.8%) prostate cancer was diagnosed by FusPbx of the PIRADS 3 lesion. In the target lesion PCa was classified as Gleason Score 3+3 in 5 patients, as 3+4 in 3, 4+3 in 1, 4+4 in 1 and 4+5 in 1 patient. In patients with negative FusPbx USPbx revealed PCa in another 7 patients (17.1%). In 5 of these GS 3+3 PCa was found, in another 2 patients GS 3+4 PCa.
Conclusions: PIRADS 3 lesion indicates an equivocal likelihood of significant prostate cancer. In our series the overall PCa detection rate was 26.8% and 14.6% for clinically significant cancer in PIRADS 3 lesions. This evokes the question, if PIRADS 3 lesions could be surveilled only. The findings should be confirmed in a larger series.
Keywords: MRI-ultrasound fusion biopsy; PIRADS score; Prostate cancer; image fusion; multiparametric MRI.