Preoperative Multiparametric Prostate Magnetic Resonance Imaging Structured Report Informs Risk for Positive Apical Surgical Margins during Radical Prostatectomy

Background The prostatic apex is the most frequent location of positive surgical margin (PSM) after surgery. Data regarding the ability of multiparametric magnetic resonance imaging (mpMRI) to prospectively identify men at risk for apical PSMs (aPSMs) using a structured report are lacking. Objectives The aims of the study are to determine and to compare the rate of aPSM in men with versus without prospectively flagged at-risk prostate lesions during clinical mpMRI interpretation using whole-mount histopathology as the reference standard. Methods This single-center, retrospective study of prospectively collected data included treatment-naive men with abnormal 3T mpMRI (PI-RADS v2 score ≥3) between January 2016 and December 2018 followed by surgery. During routine clinical interpretation, radiologists flagged prostate lesions abutting the apical most gland and/or encircling the distal most prostatic urethra using standardized language available as a "pick list"option in the structured report. Logistic regression was used to compare the rate of PSM in 2 groups (flagged vs nonflagged men). Propensity score covariate adjustment corrected for potential selection bias according to age, prostate-specific antigen (PSA), PSA density, grade group, and pT stage. The estimate was further adjusted by including surgeon as a covariate. Results A total of 428 men were included. A statistically significant higher proportion of aPSMs was noted in flagged (56% [51/91]) compared with nonflagged apical lesions (31% [105/337]; adjusted odds ratio, 2.5; 95% confidence interval, 1.6-4.1; P < 0.01). The difference in aPSM between both groups also varied according to the surgeon performing the RP. Prostate-specific antigen, PSA density, lesion size, apical location, Prostate Imaging Reporting Data System score, grade group, pT stage, and surgeon's experience were associated with higher PSM rate. Biochemical recurrence, defined as PSA greater than 0.2 ng/mL on 2 measurements after RP, was significantly associated with PSM status (propensity score adjusted odds ratio, 3.1; 95% confidence interval, 1.8-5.3; P < 0.0001); however, patients flagged by radiologists did not have a significant difference in biochemical recurrence rates as compared with nonflagged patients (P = 0.11). Conclusions Standard language built into structured reports for mpMRI of the prostate helps identify preoperatively patients at risk for aPSM. Clinical Impact Multiparametric MRI is able to identify patients at increased risk for aPSM, and this information can be conveyed in a structured report to urologists, facilitating patient counseling and treatment decisions.