Abstract
Endovascular aneurysm repair (EVAR) is a minimally invasive treatment option for abdominal aortic aneurysm (AAA). However, a major EVAR complication is endoleak, the reoccurrence of blood flow into the residual aneurysmal sac. Detection of endoleak is critical in post-EVAR surveillance, as endoleak can lead to further aneurysm growth and rupture. Usual surveillance is by ultrasound imaging, but this has some limitations. Shear wave elastography (SWE) has been suggested as a possible imaging modality for the detection of endoleak in EVAR patients, though there is limited evidence in the literature. The overall aim of this study was to investigate SWE’s application in the Otago Vascular Diagnostic Laboratory (OVD) post-EVAR surveillance cohort. This project aimed to determine if SWE values in post-EVAR AAA are a precursor in detecting endoleak.
Patients enrolled in the OVD EVAR surveillance programme between May and August 2023 were invited to participate in the study. Forty-six patients (40 men), with a median age of 77 years (range 58 – 91 years), provided informed consent for SWE alongside their routine B-mode and colour Doppler (CDU) ultrasound surveillance. The residual sac was insonated at its maximum diameter, as well as levels above and below this point, and SWE measurements were taken in different anatomical positions circumferentially within the sac.
Post data collection, occurrence of endoleak was unveiled, and 12/46 patients had type-2 endoleak detected by CDU. On average, across the whole aneurysm sac, SWE was 3.4 ± 1.0 m/s (mean ± SD). There were no significant differences (P = 0.96, unpaired Student’s t-test) between the SWE values of patients with endoleak (3.4 ± 0.80 m/s) compared to those without (3.4 ± 1.1 m/s).
Current analysis shows that SWE is not an indicator of a subsequent diagnosis of endoleak in AAA patients with EVAR. However, endoleak occurs in specific areas of the sac. Therefore, subsequent post-analysis will investigate SWE in specific regions of the sac where endoleak was detected and compare SWE to regions away from endoleak.