Staging of urinary bladder tumors by MRI: Utility of intravesical administration of an iron oxide-containing contrast medium in combination with high-resolution, T-2-weighted imaging.

Aim: To investigate superparamagnetic iron oxide (SPIO) particles as intrav esically applied contrast material in combination with high-resolution T-2- weighted MR imaging for the diagnostic assessment of urinary bladder tumors . Methods: A prospective study was performed in 40 patients with suspected urinary bladder tumors who underwent MR imaging with a body phased-array co il at 1.5 T. Prior to imaging, a SPIO-containing solution (179.2 mg Fell) w as instilled into the bladder. All patients were examined with T-2-weighted , half-fourier acquired single shot turbo spin echo sequences and T-1-weigh ted fast low angle shot sequences in 3 planes as well as a T-2-weighted tur bo spin echo sequence (TSE) using a 512 matrix. An additional gadolinium-en hanced dynamic study was performed in 33 patients. All patients underwent t ransurethral resection of the bladder or cystectomy. Results: The combinati on of intravesically applied SPIO particles and a high-resolution T2-weight ed TSE sequence depicted intravesical tumors as small as 4 mm. A reliable i dentification of the different layers of the bladder wall was possible in 5 cases only. The T-2-weighted TSE sequence allowed the correct determinatio n of the depth of infiltration in 29 of 36 patients with urothelial cancer by assessing the inner and outer boundary of the urinary bladder wall. This sequence had a diagnostic accuracy of 81% compared to 84% for the dynamic study (26/31). Conclusion: Even small tumors could be identified with the T -2-weighted TSE sequence after intravesical administration of SPIO particle s but it was not possible to reliably differentiate the layers of the bladd er wall. The results suggest that a dynamic MR imaging study cannot be disp ensed with in patients with urinary bladder cancer.