Spinal dysraphism at MR urography: Initial experience

PURPOSE: To prospectively evaluate the role of magnetic resonance (MR) urography in the radiologic assessment of patients with spina dysraphism. MATERIALS AND METHODS: Fourteen patients with spinal dysraphism were referred for MR urography with half-Fourier rapid acquisition with relaxation enhancement (RARE) (repetition time msec/echo time msec = 11.9/95) and RARE (2,800/1,100) sequences on a 1.5-T MR machine. Six patients did not tolerate MR urography owing to claustrophobia (n = 4) or flexion deformities (n = 2), giving a final success rate of 57% (eight patients). Two patients had a single kidney (one after nephrectomy, one with a cross-defused ectopic kidney). Images were jointly assessed by two radiologists and compared with excretory urographic studies. The signal intensity ratio and contrast-to- noise ratio were also calculated. RESULTS: Visualization of the kidneys, pelvicaliceal system, and ureters was better with half-Fourier RARE than with RARE imaging, whereas visualization of the bladder was comparable with both sequences. The mean signal intensity ratios for half-Fourier RARE and RARE sequences, respectively, were 16.2 ± 3.65 and 19.2 ± 3.65 (P = .58, factorial analysis of variance model), whereas the mean contrast-to-noise ratios were 55.4 ± 5.16 and 47.8 ± 5.16 (P = .34). Cortical scarring was depicted more clearly at MR urography than at excretory urography, whereas a renal calculus seen at excretory urography was not detected at MR urography. CONCLUSION: MR urography was feasible in 57% of patients with spinal dysraphism and is a safe, accurate method of evaluating the upper urinary tract.