DIAGNOSTIC ACCURACY OF DIFFUSION WEIGHTED MAGNETIC RESONANCE IMAGING IN DIAGNOSING MUSCLE INVASION IN URINARY BLADDER CANCER, TAKING HISTOPATHOLOGY AS GOLD STANDARD

Mudassar Saeed Pansota* (MS Urology), Naima Mujahid (FCPS Radiology), Fariha Mumtaz (FCPS Radiology), Muhammad Shahzad Saleem (FCPS) and Mumtaz Rasool (FCPS).

ABSTRACT

Introduction: Diffusion-weighted magnetic resonance imaging (DW-MRI) and determination of the apparent diffusion coefficient values (ADC) are modern functional MR-imaging techniques. The ADC value describes the ability of water molecules to diffuse in tissue, which is impaired by increased cellular density as is the case in tumors. Objectives: To determine the diagnostic accuracy of diffusion weighted magnetic resonance imaging in diagnosing muscle invasion in urinary bladder cancer, taking histopathology as gold standard. Materials & Methods: A total of 105 patients patients presented with hematuria >100 RBCs on high power microfield 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 tumour, 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=0.0001). 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.

Keywords: Urinary bladder cancer, Muscle invasion, Diffusion weighted imaging.