Gadolinium-enhanced Excretory MR Urography: Comparison with MR Urography Using HASTE Technique

Abstract

Purpose: To compare the feasibility of gadolinium-enhanced excretory MR urography(GEMRU) and conven-tional MR urography using the half-Fourier acquisition single-shot turbo spin-echo(HASTE) sequence in patients with hydronephrosis or non-visualized kidney. Materials and Methods: Fifteen patients with hydronephrosis or non-visualized kidney, as demonstrated by ultrasonography or intravenous urography, were enrolled in this study. Nine were men and six were women, and their age ranged from 18 to 77 (mean, 60.6) years. For all MR examinations, a 1.5-T MR unit was employed. For breath-hold MR urography, the HASTE technique(MRU) was used, and reconstruction involved the use of a maximum intensity-projection (MIP) algorithm. For gadolinium-enhanced excretory MR urography, the fast low angle shot(FLASH) 3-D method was used and images were obtained at 5, 10, 20, and 30 minutes, and reconstruction again involved the use of an MIP algorithm. In some cases, additional GEMRU was obtained 24 hours after contrast material injection, and an MIP algorithm was used for reconstruction. MRU and GEMRU were independently interpreted by two radiologists who for quantitative analysis compared SNR with CNR, and at each anatomic level qualitatively analysed morphologic accuracy and diagnostic value of the lesions. Results: In quantitative analysis, SNR and CNR differences between the two sequences at the renal pelvis and the level of the ureter were not significant (p0.05). In qualitative analysis, GEMRU was superior to M-RU for the assessment of evaluated ureter at each level(p0.05), anatomic anomaly and intrinsic tumor. Ureteral stones, however, were more easily diagnosed with MRU. Conclusion: For assessment of the ureter GEMRU is superior to MRU and has the advantage of evaluating renal function. We believe that for evaluation of the urinary tract, especially the distal ureter, GEMRU may be a valuable adjunct to routine MR urography.