VISUALIZATION OF URINARY-TRACT DILATATION - VALUE OF SINGLE-SHOT MR UROGRAPHY

The purpose of this study was to evaluate detection of urinary tract d ilatation, depiction of obstruction level and determination of cause w ith single shot MR imaging in an acquisition time of 2.8 s. Heavily T2 -weighted single-shot MR images in 50 patients with ureterohydronephro sis as suspected by ultrasound were prospectively compared with IV uro graphy and clinical outcome. Imaging techniques were obtained within a maximum time interval of 4 h and assessed independently on the same d ay. Single-shot MR urography was able to demonstrate dilatation and ob struction levels in 96% of urinary tracts in accordance with X-ray uro grams. In 4 patients with a unilaterally negative IV urogram, obstruct ion levels were demonstrated in single-shot MR urography. Single-shot MR urography did not depict 2 of 7 collecting systems with mild dilata tion and contralateral undilated ureters were not adequately visible. Single-shot MR urography consistently visualizes dilated urinary tract s and obstruction levels in moderate and severe dilatation. Single-sho t MR urography may be an alternative for IV urography in cases of rena l impairment, when iodinated contrast or the application of X-rays is contraindicated, and may help in avoiding direct ureteropyelography. S ingle-shot MR urography rarely allows determination of the cause of ur inary tract dilatation.