Role of magnetic resonance in evaluation of urinary bladder cancer

Abstract

Objective The aim of this study was to prospectively evaluate the use of MRI as a noninvasive diagnostic tool for staging of bladder tumors using different magnetic resonance (MR) sequences: T2-weighted image (T2WI), diffusion-weighted image (DWI), and precontrast and postcontrast T1-weighted image. Background MRI with its superior resolution and supplemented with new emerging sequences is the optimal imaging modality for accurate local staging of bladder cancer, particularly for differentiation between the muscle-invasive and non-muscle-invasive urinary bladder tumors; it is a cornerstone in treatment decision making. Patients and methods The study protocol received institutional ethical committee approval, and informed consent was obtained. Between November 2014 and November 2015, 50 consecutive patients (44 men and 6 women; mean age: 64.3 years; range: 44–85 years) who presented with gross hematuria or suspected urinary bladder tumors were enrolled prospectively. All patients underwent MR examination followed by conventional cystoscopy. The patients were evaluated using T2-weighted high-spatial-resolution MRI of the urinary bladder, followed by diffusion-weighted-MRI. Precontrast T1 (with or without fat suppression) and immediate postgadolinium injection were performed if there were no contraindications. Results Of all 50 patients, four (8%) were at T1, 12 (24%) were at T2, 23 (46%) were at T3, and 11 (22%) were at T4. The most common symptom was gross hematuria (33 patients; 66%). The overall accuracy of T2WI, DWI, and postcontrast imaging sequences in differentiating stage Tis to T2 tumors from T3 to T4 tumors was 88, 98, and 94%, respectively. DWI has a higher overall accuracy compared with both T2WI and postcontrast T1-weighted image in T staging of bladder cancer. Conclusion MRI with new emerging sequences (diffusion-weighted and contrast-enhanced) is highly reliable for accurate local staging of urinary bladder cancer, which is similar to that of conventional cystoscopy. This noninvasive method could be efficiently used for evaluating patients with hematuria of lower urinary tract origin.