Dynamic MRI of bladder cancer: Evaluation of staging accuracy

OBJECTIVE. The purpose of this study was to evaluate the accuracy of gadolinium-enhanced MRI in staging bladder cancer in a series of patients with Surgically proven bladder cancer. MATERIALS AND METHODS. Seventy-one patients with biopsy-proven bladder Lancer underwent MRI on a 1.5-T scanner with a phased-array pelvic coil. Conventional T1-weighted spin-echo, T2-weighted spin-echo, and unenhanced and enhanced (0.1 mmol/kg olinium) fast spoiled gradient-echo images with fat suppression were obtained. Two blinded reviewers evaluated the MR images and assigned a stage that was compared with the pathologic stage (n = 67) or with clinical follow-up for at least 2 years after MRI (n = 4). RESULTS. Agreement among the reviewers was good in assigning a radiologic weight stage for bladder cancer (kappa = 0.80). On a stage-by-stage basis, MRI accuracy was 62%. and over-staging was the most common error (32%). Staging accuracy improved to 85% and 92% in differentiating superficial front invasive tumors and organ-confined from non-organ-confined tumors. respectively. The time interval between MRI and transurethal resection 60 days and greater than or equal to 61 days was not a statistically significant factor in differenciating superficial from invasive and organ-confined front non-organ-confined tumors (p > 0.05). MRI accuracy in staging transitional cell carcinoma was not significantly different from that obtained in staging non-transitional cell carcinoma (p > 0.05). CONCLUSION. MRI shows good reproducibility between reviewers for staging bladder cancer. Although overall staging accuracy was only moderate. the accuracy for differentiating superficial versus invasive disease and organ-confined versus non-organ-confined disease was high.