RESUMO
MR urography was made in 25 patients (age 24-70, mean age 48.6 years, 20 females, 5 males) with iatrogenic injury of the upper urinary tract (UUT). A comparison group consisted of 15 patients without nephrostomic drainage who had no contraindications for intravenous contrast preparations. MR urography was performed in frontal and sagittal projections. The examination was made before and 20 min after intravenous injection of 20 mg diuretic. Five patients received additionally excretory MR urography with intravenous injection of magnevist (0.2 ml/kg, 3 ml/s just before the examination). Mean duration of urography was 21 (18-23) min. The results were compared to findings of ultrasound or x-ray investigations, diapevtic ureteroscopy or open surgical intervention. The results were similar to those of x-ray CT. In patients with ureteral obliteration MR urography was less informative than joint antegrade and retrograde ureteropyelography as the ureter could not be visualized beneath the injury. In 2 patients examined with intravenous urography and x-ray CT, definite length of ureteral stricture was obtained only with MR urography. In 5 patients with hydronephrotic transformation MR urography was much more informative than excretory urography. MR urography provided information sufficient for diagnosis. Sensitivity of MR urography and that with diuretic load was 86.8 and 92.3%, respectively. MR urography, even without contrast enhancement, provides images with high resolution sufficient for visualization of the ureter distally of the stricture and is a method of choice in patients with subnormal renal function, intolerance to iodine-containing contrast media, with hyperthyroidism and pregnant women after the first trimester.
