Introduction

Use of multiparametric MRI (mpMRI) has increased massively in prostate cancer diagnosis, not only in active surveillance and post negative TRUS biopsy, but as part of the upfront diagnostic algorithm. The prostate imaging-reporting and data system version 2 (PIRADS v2) rates the likelihood of significant prostate cancer on a scale from 1 to 5, which encompasses T2W images, diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) MRI. DCE only affects the overall PIRADS score when a lesion is deemed PIRADS 3 on diffusion weighted imaging (DWI) in the peripheral zone. The aim of this study is to assess the utility of DCE, which requires the administration of intravenous contrast, adding cost and risks to patients.

Methods

Data on all patients undergoing their first prostate mpMRI for initial diagnosis, active surveillance and previous negative biopsies were recorded into a custom-made prospective REDCap database between July 2013 and May 2016. All mpMRIs were reported by experienced radiologists.

Results

1191 mpMRI were performed during this time period. Mean patient age was 65.1 years and mean PSA was 7.43. 658 patients were undergoing their initial mpMRI without previous biopsies. Only 85 (7.1%) mpMRI had lesions with DWI PIRADS score of 3 in the peripheral zone. Of the initial mpMRIs without previous biopsies, only 56 (8.4%) had lesions with DWI PIRADS score of 3 in the peripheral zone. _x000D_ _x000D_ Of the 85 patients with a lesion that was equal to 3 on DWI in the peripheral zone, 58 had an mpMRI that had an overall PIRADS score of 3 and had a subsequent biopsy. 35 had clinically insignificant cancer or benign biopsy, 17 had grade group 2 on histology and 6 had grade group 3. 4 patients had an overall PIRADS score of 4 and a subsequent biopsy. 3 were benign or clinically insignificant cancer and 1 had grade group 2 cancer. _x000D_ _x000D_ 14 of these patients had a subsequent radical prostatectomy, which showed 1 grade group 1 histology, 7 grade group 2 histology and 6 grade group 3 histology. Lesions with DWI score of 3 only make up a small proportion of mpMRIs, and fewer patients require radical treatment._x000D_

Conclusions

DCE appears to have a minor role in determining the overall PIRADS score of a lesion and is relevant in less than 9% of cases. By omitting the DCE, and therefore contrast administration, patients would be spared risks of nephrotoxicity and anaphylaxis, and healthcare costs could be cut without reducing diagnostic accuracy in the vast majority of cases.

Funding

Ipsen and Tolmar