Diagnostic Performance of Preoperative Multiparametric MRI for Local and Nodal Staging in Penile Cancer: A Histopathology-Correlated Single-Centre Study

Background/Objectives: Histopathology-correlated evidence for preoperative magnetic resonance imaging (MRI) in penile cancer remains limited. We evaluated multiparametric MRI with artificially induced erection for local and nodal staging in surgically treated penile cancer. Methods: This prospective, single-centre diagnostic accuracy study included consecutive patients who underwent preoperative multiparametric MRI between 2017 and 2024, with postoperative histopathology as the reference standard. The primary endpoint was binary local T-staging (≤T1 vs. ≥T2). Secondary endpoints were three-category T-staging (≤T1/T2/≥T3) and binary nodal staging (N0 vs. N+) in patients with pathological nodal verification. Two radiologists independently reassessed all 38 examinations in a post hoc reproducibility analysis. Results: Thirty-eight patients were included; all tumours were glans-based and treated with organ-sparing surgery. Binary local staging showed 68.4% accuracy (95% CI, 52.5–80.9%), 88.2% sensitivity, 52.4% specificity, 60.0% positive predictive value, 84.6% negative predictive value, and balanced accuracy of 0.703 (95% CI, 0.568–0.838). Overstaging predominated (10 false-positive vs. 2 false-negative classifications; p = 0.043). Three-category exact agreement was 52.6% (κ = 0.257). In the pathologically verified nodal subset (n = 30), accuracy was 83.3% (95% CI, 66.4–92.7%), sensitivity 78.6%, specificity 87.5%, and balanced accuracy 0.830 (95% CI, 0.691–0.970). Inter-reader agreement was 92.1% for binary T staging (κ = 0.837) and 97.4% for binary N staging (κ = 0.943). Conclusions: mpMRI was sensitive but insufficiently specific for ≥T2 disease and should not independently trigger treatment escalation. Nodal performance was encouraging but arose from a guideline-selected verified subset. These findings apply primarily to glans-based, organ-preserving cohorts and do not establish an incremental benefit of erection induction.