Diagnostic performance of apparent diffusion coefficients for prostate cancer in patients with PI-RADS 4–5 lesions: a retrospective analysis

Background: While prostate biopsy is the standard diagnostic approach for Prostate Imaging-Reporting and Data System (PI-RADS) 4–5 lesions, some of these biopsies yield negative results. Objective: To determine the optimal minimum apparent diffusion coefficient (ADCmin) and prostate-specific antigen density (PSAD) threshold and develop a quantitative diagnostic standard that would enhance the diagnostic accuracy. Design and methods: The study included 361 patients who met the criteria and had undergone prostate biopsy between January 2021 and December 2024. Comprehensive clinical information was collected. Following the standardization of the region of interest protocol, apparent diffusion coefficient was measured for all PI-RADS 4–5 lesions. Univariate and multivariate logistic regression analyses were employed to identify independent predictors, and diagnostic efficacy was assessed using receiver operating characteristic curves and the area under the curve (AUC). Results: Of the 361 patients, 252 (69.8%) were diagnosed with clinically significant prostate cancer (csPCa), and 109 (30.2%) were diagnosed with clinically insignificant prostate cancer and non-prostate cancer. Multivariate analysis revealed PSAD and ADCmin to be independent predictors of csPCa. The AUC values of PSAD and ADCmin for diagnosing csPCa were 0.797 (95% CI: 0.751–0.837) and 0.777 (95% CI: 0.731–0.819), respectively. Applying the criterion of “PSAD ⩾ 0.35 ng/mL 2 and ADCmin < 0.575 × 10 −3 mm 2 /s” was found to have a high positive predictive value (94.2%) and a high specificity (91.7%) for csPCa in PI-RADS 4–5 lesions. Applying the criterion of “PSAD ⩾ 0.35 ng/mL 2 or ADCmin < 0.575 × 10 −3 mm 2 /s” substantially increased the negative predictive value for csPCa to 80.0% for PI-RADS 5 lesions. Conclusion: The results demonstrate that the ADCmin exhibits high diagnostic accuracy for detecting csPCa in patients with PI-RADS 4–5 lesions. Furthermore, diagnostic criteria were established for patients based on PSAD and ADCmin to aid in clinical decision-making regarding prostate biopsy.