Usefulness of MR Urography in the Diagnosis of Hydroureteronephrosis

Joo, Jung Hyun; Jeong, Yong Yeon; Kang, Heoung Keun; Kim, Chang Il; Chu, Sung Nam; Kim, Yun Hyeon; Seo, Jeong Jin; Park, Jin Gyoon; Oh, Bong Ryoul

Abstract

PURPOSE
To evaluate the clinical usefulness of the MR urography (MRU) in the diagnosis of hydroureteronephrosis.
MATERIALS AND METHODS
Twenty-five patients with hydronephrosis (26 cases) underwent MR urography, using a 1.5T MR scanner (Signa Horizon, GE Medical Systems, Milwaukee, U.S.A). The causes of hydronephrosis included benign ureteral stricture (12), ureteral stones (8) and malignant strictures (6), and were confirmed by operation, biopsy, conventional urography or clinical follow up. For MRU, a fat suppressed, respiratory-triggered, heavily T2-weighted fast spin echo (FSE) pulse sequence was used, and the 3-dimensional MR images were subsequently processed by a maximum-intensity-projection algorithm. We evaluated the success rate of MRU and its accuracy in determining the level and cause of obstruction, and compared the degree of hydroureteronephrosis seen on MRU with that seen on conventional urography.
RESULTS
In all cases, a urogram was successfully obtained. In determining the degree of hydroureteronephrosis and the level of obstruction (in the upper ureter in 11 cases, in the mid-ureter in four, and in the lower ureter in 11), MRU findings matched those of conventional urography. In 24/26 cases (92%), MRU accurately determined the cause of urinary tract obstruction ; the two exceptions were in cases involving ureteral stones.
CONCLUSION
MRU is a promising, noninvasive diagnostic method for evaluating hydroureteronephrosis, especially in children, pregnant women and patients with an allergic reaction to iodinated contrast material.