sUse of a 2 Dimensional Vessel Navigator Roadmap Decreases Patient Radiation Dose Compared to Standard 3D Mapping for Fenestrated Endovascular Aneurysm Repair.

ABSTRACT Objective : For fenestrated endovascular aneurysm repair (FEVAR), the implementation of the VesselNavigator (Philips Healthcare, Best, The Netherlands) to provide a three-dimensional vessel roadmap has been shown to reduce patient radiation exposure. Unfortunately, FEVAR radiation doses remain substantial despite utilization of this technology. Traditionally, registration of the live fluoroscopy with the pre-operative CTA is performed via the acquisition of a low-dose cone-beam CT scan. However, this registration can also be accomplished with the acquisition of 2D x-rays using the c-arm in two different projection angles. We hypothesized that the 2D image acquisition for vessel roadmap development would result in a significant reduction in patient radiation dose in comparison to the 3D CT registration without compromising image quality or increasing procedural length. Methods : This single-center, retrospective study included FEVARs performed from 1/2015 to 5/2019. For patient data, the cumulative reference air kerma (RAK) was presented as geometric mean and standard deviation. A general linear model with log-normal distribution was used to test the difference in patient RAK between 2D x-ray and 3D CT VesselNavigator registration after adjusting for BMI and the number of vessel fenestrations (1-2 vs 3-4). Fluoroscopy time was recorded and used as a surrogate for case complexity. All analyses were done in SAS 9.4 (SAS Institute, Inc., Cary, NC). Results : 164 FEVARs were performed on a Philips Allura Xper FD 20 fluoroscopy system equipped with clarity technology. The VesselNavigator registration was completed using 3D CT mapping in 99 cases and 2D x-rays in 65 procedures. On average, utilization of 2D mapping vs 3D mapping for the VesselNavigator resulted in a 20.4% reduction in patient RAK after controlling for BMI and number of vessel fenestrations, p= 0.0135. There was no significant difference in fluoroscopy time between the two study groups (p=0.81) suggesting that image quality was not compromised by the use of 2D mapping leading to the need for additional fluoroscopy. Conclusion : Acquisition of 2D films rather than a 3D CT scan for VesselNavigator registration allows for a significant reduction in patient radiation dose during FEVAR without increasing the case complexity or compromising image quality.