Multi-detector row CT urography: Comparison of strategies for depicting the normal urinary collecting system

PURPOSE: To evaluate several protocols for depiction of the urinary collecting system with multi-detector row computed tomographic (CT) urography. MATERIALS AND METHODS: Fifty-one patients with hematuria or a suspicious renal mass underwent CT urography, during which thinly collimated (1-mm) pyelographic phase scanning was performed 8-10 minutes after contrast medium administration. Patients were examined while prone only (n = 17) and while both prone and supine in = 17) after a 250-mL infusion of normal saline. Each collecting system and ureter was divided into six segments that were assigned opacification scores. All acquisition techniques were compared, and the highest-scoring technique was compared with that in 17 patients who underwent conventional intravenous urography (IVU). Three reconstruction techniques (transverse, coronal, and maximal intensity projection) were also compared. Stratified analysis was performed with the paired two-tailed Student t test to compare opacification scores for both the acquisition techniques and display methods, both individually and in all possible combinations. RESULTS: CT urography with supplemental saline administration, performed with the patient prone or supine, significantly improved mean opacification scores in the distal ureters (right, P = .004; left, P = .006). With this technique, CT urography produced a mean opacification score that was not significantly different from that with IVU in 11 of 12 segments and was significantly better than that with IVU in one of 12 segments (lower left ureter). Mean opacification scores obtained with transverse or coronal displays were equal to or higher than those obtained with maximum intensity projection reconstructions in all segments. CONCLUSION: CT urography with a multi-detector row scanner and supplemental infusion of normal saline reliably displays the opacified urinary collecting system.