Triphasic helical CT of the kidneys: Contribution of vascular phase scanning in patients before urologic surgery

OBJECTIVE, The purpose of this study was to evaluate: the potential benefit s of performing vascular phase scanning of the kidneys in addition to unenh anced and parenchymal phase contrast-enhanced CT in patients being examined for urologic surgery. MATERIALS AND METHODS. Parenchymal and vascular phase images from triphasic renal helical CT of 50 patients were sequentially evaluated in a randomize d, retrospective fashion by two independent observers. The number of renal arteries and veins and the presence of vein or collecting system anomalies were recorded for each scan phase along with a subjective 10-point-scale sc ore of the visibility of the vasculature and collecting system. Correlation of these findings was made with surgical or angiographic findings in 67 of the 87 kidneys and was made by consensus review in the remaining 20 kidney s. RESULTS, Accessory renal arteries were seen significantly more often (p < . 05, chi-square test) on the vascular phase scans. The subjective scores for the visibility of the renal arteries and renal veins were significantly hi gher on the vascular phase scans (p < .0001, Wilcoxon's rank sum test). The subjective scores for the visibility of the filling of the collecting syst em and renal pelvis were significantly higher for the parenchymal phase sca ns, despite the use of a small contrast bolus before each scan (p < .0001,W ilcoxon's rank sum test). CONCLUSION. Triphasic renal CT better reveals the artery and vein anatomy o f the kidney than does parenchymal phase imaging only. Triphasic helical CT is indicated in patients undergoing planning for urologic surgery when vas cular anatomy is clinically important.