Multi-slice spiral CT urography in the diagnosis of urinary congenital abnormities

Objective: To evaluate the imaging methods, characteristics, diagnostic value of multi- slice CT urography (MSCTU) in congenital abnormities of urinary system. Methods: To collect 33 urinary congenital abnormities cases in three years and to analyses these MSCTU images. All examinations were performed with a multi-slice spiral CT scanner. The patients were intravenously injected with 90 ml of Iohexol 300 with a power injector at the rate of 3 ml/s. Nephrographic-phase images were obtained at 75 s after initiation of the injection of contrast material, the appropriate delay time is according to Kidney's enhancement extent and nephrohydrosis degree. Excretory-phase images were obtained through the abdomen and pelvis from 10 min. to 23 h after initiation of the injection of contrast material without abdominal compression. Excretory-phase images were transferred to the workstation and performed maximum intensity projection (MIP), multiplanar reconstruction (MPR), volume rendering (VR), and virtual cystoscopy (VC). Results: The urinary congenital abnormities diagnosed by MSCTU in 33 cases, including 1 ectopic kidney, 1 horseshoe kidney, 1 renal malrotation, 2 supernumerary kidneys, 2 ureteral valves, 2 retrocaval ureters, 4 congenital megaureters, 6 ureteropelvic junction stenosis, 9 pelviureteric duplication malformations and 5 bladder diverticula. The displaying rate of ureter was 91% (61/66). The scanning time of excretory-phase was less than 20 seconds in All cases. The average CT value of contrast media in displayed ureter lumens was 520 HU. The postprocessing images had clear, dimensional feature and It was satisfy the diagnosis. Conclusion: MSCTU has clear, dimensional feature and has strong ability of displaying total anatomy shape and tiny pathology change of congenital abnormities in the urinary system. It is a very useful method for detecting the congenital abnormities in the urinary system. (authors)