Preoperative T Staging of Urinary Bladder Cancer: Efficacy of Stalk Detection and Diagnostic Performance of Diffusion-weighted Imaging at 3T

Abstract

Purpose: We evaluated the ability of diffusion-weighted imaging (DWI) at 3 tesla for diagnosing T stage and detecting stalks in bladder cancer.
Methods: In total, 39 consecutive patients with bladder tumors underwent magnetic resonance (MR) imaging that included T₂-weighted imaging (T₂WI) and DWI using a 3T MR scanner. Two radiologists interpreted T₂WI plus DWI and T₂WI for diagnosis of T stage and for detection of stalks. We used McNemar’s test to examine differences in diagnostic performance and Fisher’s exact test to evaluate differences in stalk detection frequency.
Results: Specificity and accuracy in differentiating T1 tumors from T2 to T4 tumors were significantly better with T₂WI plus DWI (83% [20/24] and 85% [33/39]) than T₂WI (50% [12/24] and 67% [26/39]; P = 0.02), and accuracy for diagnosing tumor stage was significantly better with T₂WI plus DWI (82% [32/39]) than T₂WI alone (59% [23/39]; P = 0.03). The observers identified stalks in 11 tumors by T₂WI (48% [11/23]) and 17 by DWI (74% [17/23]) (P < 0.03).
Conclusion: DWI at 3T was superior to T₂WI for evaluating the T stage of bladder cancer, particularly in differentiating T1 tumors from those T2 or higher, and in detecting stalks of papillary bladder tumors.