Title: Three-Dimensional Contrast-Enhanced Ultrasound Improves the Detection and Classification of Endoleaks Following Endovascular Aneurysm Repair
Abstract: Introduction: Life-long surveillance following EVAR is recommended to detect stent-graft related complications, of which, endoleak is by far the most common. The move away from computed tomographic angiography (CTA) based surveillance following EVAR has seen an evolving role for ultrasound modalities. Three-dimensional contrast-enhanced ultrasound (3D-CEUS) has potential to refine ultrasound-based diagnosis of endoleak and reduce the need for CTA and catheter angiography. This study compares the ability of 3D-CEUS and CTA to detect and classify endoleaks following EVAR. Inter-operator variability for detection and classification of endoleak by 3D-CEUS was studied. The 3D-CEUS diagnosis was compared with the CTA but also on the final decision of the vascular multi-disciplinary team (MDT). Methods: Patients undergoing CTA as part of the EVAR surveillance programme were recruited. Patients attended for 3D-CEUS on the same day as the CTA or as close to the same date as possible. 3D-CEUS was performed using SonoVue contrast and a freehand 3D-US system using electromagnetic tracking, coupled with a Philips iU22 unit. For both CEUS and 3D-CEUS, images were acquired by an accredited and experienced vascular scientist. Each image pair was then independently analysed by two blinded vascular scientists with experience in CEUS and 3D-CEUS. Each CTA was analysed and reported by a consultant vascular interventional radiologist. Inter-operator reliability of 3D-CEUS was examined with the kappa statistic. Results: 100 paired CTA, CEUS and 3D-CEUS studies were analysed. Assuming CTA to be the gold standard, the sensitivity, specificity, positive, and negative predictive value of 3D-CEUS to detect all endoleaks was 96%, 91%, 90%, and 96% respectively. Taking the MDT decision to be the ‘gold standard’, the sensitivity, specificity, positive, and negative predictive value of 3D-CEUS was 96%, 100%, 100% and 96%. The kappa statistic for inter-operator agreement of endoleak presence and type was 0.89. 3D-CEUS more accurately reflected the final MDT decision on the presence and type of endoleak. Conclusion: 3D-CEUS is more sensitive and accurate than CTA for endoleak detection and classification following EVAR. 3D-CEUS is now our investigation of choice if the AAA continues to grow or an endoleak is detected on standard duplex imaging. Disclosure of Interest: None Declared.