Retrospective analysis of the effect of crossing vessels on successful retrograde endopyelotomy outcomes using spiral computerized tomography angiography.

PURPOSE: Using spiral computerized tomography (CT) angiography, we sought to evaluate the incidence of a crossing vessel in a group of adults with primary ureteropelvic junction obstruction who had previously undergone successful retrograde endopyelotomy. MATERIALS AND METHODS: A total of 16 patients who had undergone successful Acucise balloon incision endopyelotomy for ureteropelvic junction obstruction, all with followup greater than 2 years, underwent a spiral CT angiogram with intravenous contrast material to identify those with a crossing vessel. Contrast enhanced CT was performed with dual phase technique on a Somatom-Plus-S CT scanner using prototype software. After 180-degree linear interpolation of the projection data, transaxial images of the affected kidney were reconstructed. In addition, at the time of the study all patients completed analog followup pain scales and quality of life assessment questionnaires. RESULTS: Among the 16 patients 6 (38%) had anterior or posterior crossing vessels based on spiral CT angiography. No patient had both types. By analog pain scale patients had 80% mean improvement in pain (range 63 to 100). CONCLUSIONS: In our series nearly 40% of patients with anterior or posterior crossing vessels had a long-term (greater than 2 years) successful outcome with retrograde endopyelotomy. Endopyelotomy continues to be our initial mode of therapy among adults with primary ureteropelvic junction obstruction. In our opinion the adverse influence of the crossing vessel is not sufficient to justify the added expense of preoperative angiography, spinal CT or endoluminal ultrasound.

Dynamic incremental CT: effect of volume and concentration of contrast material and patient weight on hepatic enhancement.

PURPOSE: To develop an individualized approach to the intravenous administration of contrast material for hepatic computed tomography (CT). MATERIALS AND METHODS: Two hundred patients were randomized into eight protocols. Each group received different volumes and concentrations of contrast material. For each protocol, maximum hepatic enhancement (MHE) was calculated, with an adjustment for iodine dose and patient weight. The contrast enhancement index (CEI) and optimum scanning interval were calculated for hepatic enhancement thresholds of 10-60 HU. RESULTS: The MHE calculated as a function of patient weight was 96 HU +/- 19 per gram of iodine per kilogram of body weight. CEIs obtained with a contrast material concentration of 240 mg of iodine per milliliter were inferior to those obtained with a concentration of 320 or 350 mg I/mL. At low enhancement thresholds, the volume of contrast material had a more important effect than the concentration on CEI and optimum scanning interval; at high thresholds, concentration had a more important effect. CONCLUSION: For a patient of known weight, one can calculate the iodine dose needed to provide a desired level of hepatic enhancement. Use of a contrast material with a concentration of 240 mg L/mL is not recommended for dynamic incremental hepatic CT, except in small patients (eg, those weighing less than 73 kg).