Our purpose was to evaluate the accuracy of MR imaging–based preoperative staging in patients with urinary bladder cancer compared to surgical-pathological staging as the gold standard.
METHOD AND MATERIALS
Fourty patients with tumors of the urinary bladder diagnosed on cystoscopy underwent MR imaging of the pelvis. Patients were examined according to a standard protocol that was developed to evaluate bladder tumors. The findings obtained by MR imaging were analyzed and classified according to the TNM system. The stage of the tumor was individually determined and compared with the findings from surgery and pathology.
According to the results from urologic surgery and pathology, 37 out of 40 patients had transitional cell carcinoma of the urinary bladder. Two had squamous cell carcinoma and one had adenocarcinoma. In 27 out of 40 cases (67.5%) MR imaging based staging matched the results obtained from surgery and pathology. In 13 out of 40 cases (32.5%) discordance was found. MR imaging resulted in overstaging in 11 cases (27.5 %) and understaging in 2 cases (5%). The vast majority of discordances occured in the evaluation of superficial or low stage tumors. High correlation was found with stage T3- (100%) and T4-tumors (90%).
The results of this study suggest a high accuracy of MR imaging in the staging of T3 and T4 bladder tumors. We conclude that MRI should be used in routine staging of bladder cancer, especially when invasion beyond the muscularis propria is suspected.