Diagnostic Value of Dynamic Contrast-Enhanced MRI for the Detection of Clinically Significant Prostate Cancer in a Multi-Reader Study: Preliminary Results from the PI-CAI Consortium

PURPOSE: The study aimed to compare the detection performance of ISUP grade group (GG) >= 2 using bi-parametric (bp)MRI, and multi-parametric (mp)MRI (which includes dynamic contrast IV administration), in an international reader study. METHODS: This retrospective reader study uses a cohort of 400 prostate mpMRI exams acquired between 2012-2021 at three Dutch and one Norwegian centres. Patients suspected of GG>=2 cancers and without prior prostate treatment or prior GG>=2 findings in an MRI-first approach are included. 65 radiologists (18 countries, 43 centres) with 1-23 years (median: 8) prostate reading experience were enlisted. Readers and cases are divided into blocks of 100 cases. For each case, readers assessed bpMRI and mpMRI in sequence to mimic theclinical routine. Suspected GG>=2 cancer findings were assigned a PI-RADS 3-5 score. Additionally, a patient-level suspicion score (0-100) of harbouring GG>=2 was indicated. Multi-reader multi-case (MRMC) analysis was used to compare the patient-level addedvalue of mpMRI. RESULTS: Preliminary results from the first 14 readers with 2-15 years (median: 9) of experience indicate that overall, there is little improvement in GG>=2 detections between bpMRI and mpMRI readings with AUROCs of 0.857 (95% CI: 0.83, 0.89) and 0.860 (95% CI: 0.83, 0.89), respectively. For individual readers, absolute differences in AUROC ranged between 0.00-0.03 (95% CI: 0.00, 0.01). CONCLUSION: MRI assessments in bpMRI had similar GG>=2 detections to mpMRI assessments at a per-case level. Multivariable influencers such as experience, workflow, image quality and protocol familiarity must be evaluated. LIMITATIONS: Preliminary results are limited by the sample size. mpMRI readings of the original data were used to guide histologic verification. 13 out of 14 readers had high expertise as per 2020 ESUR/ESUI consensus statements.