Diagnostic Accuracy of Diffusion Weighted Magnetic Resonance Imaging in Diagnosing Muscle Invasion in Urinary Bladder Cancer Taking Histopathology as Gold Standard
Background: MRI is the most common investigation to diagnose bladder cancer. The efficacy of Diffusion weighted MRI in diagnosing muscle invasion in bladder cancer is questionable. Objective: To determine the diagnostic accuracy of diffusion weighted magnetic resonance imaging in diagnosing muscle invasion in urinary bladder cancer, taking histopathology as gold standard. Study Design: Cross-sectional validation study. Settings: Department of Radiology, DHQ Teaching Hospital, Sargodha Pakistan. Duration: August 01, 2018 to February 28, 2019. Methods: A total of 105 patients presented with hematuria >100 RBCs on high power micro field and irregular soft tissue structure projecting into bladder lumen from a fixed mural site on ultrasonography and age 25-65 years of either gender were included. Patients with h/o radiotherapy, CRF, recurrent tumor, biopsy proven muscle invasive urinary bladder cancer and any contraindication to MRI were excluded. All the patients were then underwent DW-MRI of the pelvis. DW-MRI findings were interpreted for presence or absence of muscle invasion in urinary bladder cancer and compared with DW-MRI findings. Results: In DW-MRI positive patients, 64 (True Positive) had muscle invasion and 03 (False Positive) had no muscle invasion on histopathology. Among 38, DW-MRI negative patients, 03 (False Negative) had muscle invasion on histopathology whereas 35 (True Negative) had no muscle invasion on histopathology (p=O.OOOI). Overall sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of diffusion weighted magnetic resonance imaging in diagnosing muscle invasion in urinary bladder cancer was 95.52%, 92.11%, 95.52%, 92.11% and 94.29% respectively. Conclusion: This study concluded that DW-MRI is a highly sensitive and accurate non-invasive modality for diagnosing muscle invasion in urinary bladder cancer.