Prostate Multiparametric-MRI (mp-MRI) Accuracy for Localization of Clinically Significant Prostate Cancer: A Retrospective Comparative Study between MRI and Whole-mount Histopathology

Introduction: Multiparametric magnetic resonance imaging (mpMRI) has been increasingly used to guide prostate cancer management. Most studies are focusing on the detection of prostate cancer rather than localization of tumors within the gland, which is fundamental to plan treatment. We aimed to evaluate mpMRI for accurate localization of tumor nodules and examining the predictors of detection. Methods: Retrospective study of 30 prostate cancer (PCa) patients who underwent mp-MRI before radical prostatectomy (RP). Suspicious lesions on mpMRI were localized using a standardized prostate map of 24 regions of interest (ROI) and compared with whole-mount histopathology. Results: Seven hundred and twenty ROIs were evaluated and 160 had clinically significant PCa (lesions ≥5 mm or Gleason ≥6). Sensitivity and specificity for the detection of PCa on hemiprostates was 82% and 80%. PCa mapping was less sensitive for octants - 52%, but specificity was higher, at 95.9%. mpMRI had better performance for Gleason >7 and tumor dimension ≥ 1cm. MRI correctly identified the location of 80% of index lesions. The extracapsular invasion was correctly detected in 90% of patients. Tumor volume had a strong correlation between mpMRI and RP analysis, with an approximate 10% underestimation of tumor dimensions. (rho =0.73; <0.001). Conclusion: mpMRI is capable of accurate localization of clinically significant PCa within whole mount prostate, with moderate sensitivity and good specificity. mpMRI performance increases with ISUP ≥ 3 and size ≥ 1 cm. Extracapsular invasion detection and high sensitivity of hemiprostatic localization make this exam vastly relevant for nerve-sparing treatment planning.