ADC in the evaluation of side-specific extracapsular extension of prostate cancer: development and internal validation of a nomogram of clinical utility

Purpose: To develop a nomogram of clinical utility based on diffusion- weighted imaging to predict side -specific extracapsular extension. Methods and Materials: Seventy men underwent 1.5 T multiparametric magnetic resonance imaging followed by radical prostatectomy . Apparent diffusion coefficient (ADC) values were assessed for normal and pathological tissue, and their ratio. Univariate and multivariate logistic regression analyses were performed. Logistic regression coefficients were used to develop our nomogram. Receiver operating characteristic curve analysis was performed to determine the optimal ADC cut -off for extracapsular extension. Results: At univariate analysis, ADC ≤ 0.84 x 10 -3 mm2/s and ratio ≤ 0.60 were associated with extracapsular extension (p < 0.001 ) along with suspicious extracapsular extension at imaging (p = 0.003) and biopsy Gleason score (p < 0.001). At multivariate analysis, ADC (p = 0.031), extracapsular extension on T2- weighted images (p < 0.001) and biopsy Gleason (p = 0.001) maintained thei r independent predictor status. Our nomogram showed a significant higher sensitivity (96%) than T2- weighted images (54%; p =0.001) and diffusion- weighted imaging alone (79 %; p = 0.045). Conclusion: We developed a nomogram predicting side- specific extracapsular extension in prostate cancer. ADC represents a potential imaging biomarker to predict side -specific extracapsular extension in patients with prostate cancer. The nomogram aims to assist clinicians in confirming extracapsular extension. Our nomogram could improve the current diagnostic pathway and possibly the therapeutic approach for this disease