MR urography in the diagnosis of urinary tract obstruction

To evaluate the efficiency of MR urography in depicting the urinary tract.

33 patients with urinary tract abnormalities were additionally evaluated with MR urography. 25 had dilated upper urinary tracts because of urinary obstruction and 8 had normal tracts. MR urography was performed with a 1,5T magnet using a heavy T2w sequence (3D-IR-TSE) in the coronal plane. Images were post-processed using the MIP algorithm. Both reconstructed and source images were evaluated. The results of MR urography were compared with the final diagnosis, which was established surgically in 23 cases, and with multimodality imaging workup in 10 cases.

MR urography correctly depicted the level of obstruction and the degree of dilatation of the urinary tract in all 25 patients with hydronephrotic kidneys (sensitivity 100%). Additionally, it succeeded in suggesting the underlying pathology in 25 cases (48%). Concerning the 8 patients without dilatation of the urinary tract, there was either no depiction or depiction was bad.

MR urography, a new noninvasive technique, demonstrates 100% sensitivity in diagnosing urinary tract obstruction and also suggests the underlying pathology in many cases. In nondilated systems it is not possible to get good images because MR urography only depicts fluid in the urinary tract. Thus we believe that MR urography can provide a reliable alternative in selected cases as opposed to other more invasive modalities, such as retrograde or antegrade urography, and is without the risk of contrast media and radiation exposure.