Fusion Imaging Guided EVAR Reduces Radiation - The Results of a Prospective Radiation Evaluation During EVAR (REVAR)

Abstract

Introduction - The objective of this study was to perform a multicentre prospective observational study evaluating radiation exposure during abdominal aorta aneurysm (AAA) endovascular repair (EVAR), performed under intraoperative guidance with pre-operative CTA fusion in a modern hybrid room. Methods - Between February and November 2016, all consecutive patients with AAA treated with a bifurcated endograft in a hybrid room under fusion imaging guidance were prospectively enrolled in six high volume aortic centres (from Europe (n=4), the United States (n=1) and Japan (n=1)). Patients with planned additional procedures (embolisation of an internal iliac artery for example), patients treated in an emergency setting and patients who decline enrollment were excluded. All centres followed the As Low As Reasonable Achievable (ALARA) principles and used a common dose protocol (for both fluoroscopy and angiography). Demographic data including Body Mass Index (BMI), indirect dose-area product (DAP), cumulative air-kerma (CAK), variables influencing dose delivery and contrast media volume were collected. Results are presented as percentage and 95% interval of confidence (IC), or median with interquartile range. Results - 85 patients (90.4% males) were enrolled. The median age was 75 years (69-81), and the median BMI was 27.4 (24.7-30.6). Median time to prepare the fusion mask on the workstation was 5 minutes, and the median registration time was 4 minutes. Median DAP and CAK were respectively 14.7 (10.0-27.7) Gy.cm2 and 107 (68.0-189.0) mGy. Median contrast medium volume was 47cc (35.0-70.0) (equivalent to 14.1g of Iodine (10.5-21.0)). Primary technical success was 100%. Additional unplanned procedures were performed after the completion angiography in 11 patients. One centre only included one patient and was thus excluded from the following evaluation. Median DAP per center was respectively 28.1 (n=16, 12.6-47.1), 15.9 (n=11, 11.9-22.5), 14.2 (n=12, 10.9-25.7), 20.2 (n=18, 7.0-39.5) and 10.3 (n=27, 8.2-14.7) Gy.cm2, (p=0.015). In multivariate analyses, fluoroscopy time (0.05 per minute, IC95%[0.04;0.06], p<0.001) and BMI (0.07 per kg/m2, IC95%[0.06;0.09], p<0.001) were associated with an increased DAP. Collimation was the only factor significantly associated with DAP reduction (-0.014 per percentage of collimation, IC95%[-0.019;-0.008], p<0.001). Conclusion - The routine use of fusion and following the ALARA principles was associated with low levels of radiation and contrast medium volume in all teams. This demonstrates that previously published low dose reports during EVAR performed in a last generation hybrid room (1) can be achieved in most centers.