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OBJECTIVES:
FEVAR of complex aortic aneurysms requires high quality CT angiography for custom device planning and possible intra-operative guidance using image fusion technology. At our institution, patients with stage 3-4 (CKD) have undergone cd-CTA with 40 ml of intra-aortic contrast for FEVAR planning. Recently, we have changed our protocol to utilize only 20 ml of contrast with the goal of decreasing the risk of acute kidney injury (AKI) while maintaining adequate imaging quality. The purpose of this study is to evaluate the applicability of low dose cd-CTA in performing complex aortic repairs as well as the incidence of AKI.
METHODS:
Six patients of mean age 72 (58-80) undergoing pre-operative planning for FEVAR with stage 3-4 CKD underwent cd-CTA. The protocol for cd-CTA included placement of a catheter in the descending thoracic aorta under fluoroscopy. CT images were obtained after intra-aortic injection of 20 ml of Omnipaque 350 (GE Healthcare, Princeton, NJ) diluted with 60 ml of normal saline at a rate of 6 ml/s. All patients received pre- and post-scan hydration. Serum creatinine/eGFR levels were obtained before the scan and 3-9 days afterward. Two vascular surgeons with 8 and 3 years experience performing FEVAR evaluated the images independently using Aquarius iNtuition software (TeraRecon, Foster City, CA) to determine if measurements could be accurately obtained for custom device fabrication.
RESULTS:
The mean serum creatinine level at baseline was 2.3 mg/dl (1.7-2.5) and the mean estimated GFR was 28.8 ml/min/1.73 m2 (19-39). The mean follow-up was 5.8 days (3-9) and the mean change in creatinine was -0.3 mg/dl). Four of the patients were discharged the same day as the scan. All of the cd-CTAs were deemed adequate for pre-operative planning by both surgeons. Five patients have undergone aortic repair with 100% technical success, target vessel patency and exclusion of their aneurysm. The remaining patient has elected to undergo surveillance of their aneurysm.
CONCLUSIONS:
cd-CTA of the abdomen utilizing only 20 ml of contrast with same day discharge is feasible for FEVAR pre-operative planning. Target vessel patency as well as success of FEVAR does not appear to be impacted with this technique. Although no acute deterioration in kidney function was observed ,larger series are required for validation.