Value of 3‐Tesla multiparametric magnetic resonance imaging and targeted biopsy for improved risk stratification in patients considered for active surveillance

Objective To evaluate the role of multiparametric magnetic resonance imaging (mp MRI ) of the prostate and transrectal ultrasonography guided biopsy ( TRUS ‐Bx) with visual estimation in early risk stratification of patients with prostate cancer on active surveillance ( AS ). Patients and Methods Patients with low‐risk, low‐grade, localised prostate cancer were prospectively enrolled and submitted to a 3‐T 16‐channel cardiac surface coil mp MRI of the prostate and confirmatory biopsy ( CB x), which included a standard biopsy ( SB x) and visual estimation‐guided TRUS ‐Bx. Cancer‐suspicious regions were defined using Prostate Imaging Reporting and Data System ( PI ‐ RADS ) scores. Reclassification occurred if CB x confirmed the presence of a Gleason score ≥7, greater than three positive fragments, or ≥50% involvement of any core. The performance of mp MRI for the prediction of CB x results was assessed. Univariate and multivariate logistic regressions were performed to study relationships between age, prostate‐specific antigen ( PSA ) level, PSA density ( PSAD ), number of positive cores in the initial biopsy, and mp MRI grade on CB x reclassification. Our report is consistent with the Standards of Reporting for MRI ‐targeted Biopsy Studies ( START ) guidelines. Results In all, 105 patients were available for analysis in the study. From this cohort, 42 (40%) had PI ‐ RADS 1, 2, or 3 lesions and 63 (60%) had only grade 4 or 5 lesions. Overall, 87 patients underwent visual estimation TRUS ‐Bx. Reclassification among patients with PI ‐ RADS 1, 2, 3, 4, and 5 was 0%, 23.1%, 9.1%, 74.5%, and 100%, respectively. Overall, mp MRI sensitivity, specificity, positive predictive value, and negative predictive value for disease reclassification were 92.5%, 76%, 81%, and 90.5%, respectively. In the multivariate analysis, only PSAD and mp MRI remained significant for reclassification ( P < 0.05). In the cross‐tabulation, SB x would have missed 15 significant cases detected by targeted biopsy, but SB x did detect five cases of significant cancer not detected by targeted biopsy alone. Conclusion Multiparametric magnetic resonance imaging is a significant tool for predicting cancer severity reclassification on CB x among AS candidates. The reclassification rate on CB x is particularly high in the group of patients who have PI ‐ RADS grades 4 or 5 lesions. Despite the usefulness of visual‐guided biopsy, it still remains highly recommended to retrieve standard fragments during CB x in order to avoid missing significant tumours.