Diffusion-weighted MR imaging for urinary bladder carcinoma: initial results

The aim of this study was to demonstrate the feasibility of using diffusion-weighted (DW) magnetic resonance (MR) imaging under free breathing for the detection of a urinary bladder carcinoma. In 15 patients with 17 urinary bladder carcinomas, DW images were obtained in the axial plane under free breathing scanning with a multisection spin-echo type single-shot echo planar sequence with a body coil. DW images were evaluated based on cystoscopic findings. Moreover, the apparent diffusion coefficient (ADC) value was measured in a circular region of interest (ROI) within the carcinoma, urine, normal bladder wall, prostate and seminal vesicle. In the results, on the DW images, all 17 carcinomas were clearly shown as high signal intensity relative to the surrounding structure. The ADC value (×10⁻³ mm²/s) in the carcinoma was 1.18±0.19, which was significantly lower compared with that of urine (3.28±0.20), the normal bladder wall (2.27±0.24), prostate (transition zone: 1.57±0.09, peripheral zone:1.85±0.22) and seminal vesicle (2.01±0.22). In conclusion, DW images under free breathing enabled the clear detection of the urinary bladder carcinoma, whose ADC values were lower compared with those of the surrounding structure. The DW images may be useful in evaluating tumors invading to the surrounding structures.