DIAGNOSTIC ACCURACY OF MRI PI-RADS TO DIAGNOSE PROSTATE CANCER, KEEPING HISTOPATHOLOGY AS GOLD STANDARD

ABSTRACT OBJECTIVES This study aimed to evaluate the diagnostic accuracy of mpMRI using PI-RADS v2 in a prospective study, with histopathology as the reference standard. METHODOLOGY This prospective single-centre diagnostic accuracy study was conducted between January 2022 and June 2023 in the Department of Radiology, Hayatabad Medical Complex, Peshawar, Pakistan, in accordance with STARD guidelines. A total of 127 men (aged 40-85 years) with elevated prostate-specific antigen (PSA >4 ng/dL) and abnormal digital rectal examination findings were enrolled by a consecutive sampling method. The study was conducted at the Department of Diagnostic Radiology, Hayatabad Medical Complex, Peshawar, over a period of 6 months. All participants underwent mpMRI with PI-RADS scoring followed by systematic prostate biopsy. Clinically significant prostate cancer was defined as a Gleason score ≥7. Diagnostic accuracy metrics, including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy, were calculated. RESULTS Prostate cancer was histopathologically confirmed in 58.3% (74/127) of patients. Using a predefined diagnostic threshold of PI-RADS ≥4 versus <4, mpMRI demonstrated a sensitivity of 89.2%, specificity of 81.1%, PPV of 86.8%, NPV of 84.3%, and overall accuracy of 85.8%. Performance was superior in patients with PSA >10 ng/dL (92.5% sensitivity) and for PI-RADS 5 lesions (94.7% concordance with high-grade cancer). False negatives were predominantly anterior zone tumors (75%), while false positives were primarily due to prostatitis. Inter-reader agreement was substantial (κ = 0.72). CONCLUSION In this study, mpMRI using PI-RADS v2 showed good diagnostic performance and reproducibility for detecting csPCa in a Pakistani cohort. Limitations persist in anterior zone assessment, and inflammatory mimics were observed, underscoring the need for careful interpretation and optimized biopsy strategies.