HELICAL (SPIRAL) CT ANGIOGRAPHY FOR IDENTIFICATION OF CROSSING VESSELS AT THE URETEROPELVIC JUNCTION

OBJECTIVE. The purpose of this study was to determine the feasibility of imaging crossing vessels at the ureteropelvic junction (UPJ) with h elical (spiral) CT angiography for planning surgical repair of symptom atic UPJ obstruction. SUBJECTS AND METHODS. Twenty-four consecutive pa tients with symptomatic UPJ obstruction were imaged with dual-phase, c ontrast-enhanced helical CT (collimation, 3 mm; pitch, 1.3-1.7; recons truction interval, 2 mm; early phase, 20-42 sec; and delayed phase, 90 -112 sec after initiation of IV contrast material injection [125 mi of ioversol containing 320 mg of iodine per mi, delivered at 4-5 ml/sec] ). All imaging data were viewed interactively on an imaging workstatio n. Prospective on-line interpretations were correlated with subsequent surgical and clinical findings at laparoscopy (n = 3), open surgical repair (n = 2), or ureteronephroscopic endopyelotomy (n = 11). Vessels at the UPJ that were 2 mm or more in diameter were believed to be sig nificant. Review of the transaxial images was performed to determine q ualitatively the relative usefulness of the early versus the delayed p hases for distinguishing arteries from veins. Multiplanar reformations also were retrospectively reviewed and compared with direct pyelogram s to determine the accuracy with which the location of the UPJ and the proximal ureteral course were depicted with helical CT. RESULTS. Elev en of 24 (46%) patients collectively had 11 anterior and three posteri or vessels (greater than or equal to 2 mm in diameter) crossing the UP J on helical CT, Distinction between arteries and veins was significan tly better on early-phase than an delayed-phase images (p = .01). Visu alization of the UPJ and the proximal ureteral course was good or exce llent for 18 (78%) of 23 patients for whom pyelograms were available, regardless of the presence of a ureteral stent (p > .05). Laparoscopy and open surgery findings were in agreement with the helical CT angiog rams for five of five patients. Uncomplicated endopyelotomy was perfor med for 11 patients in whom no significant vessels were seen posterior or posterolateral to the UPJ. CONCLUSION. Helical CT angiography can depict vessels crossing the UPJ and is valuable in planning surgical m anagement.