Development of a Novel Index to Characterise Arterial Physiology Using Ultrasound Imaging

Abstract

Joel Ward^1*, Xinhao Cheng^2*, Pierfrancesco Lapolla¹, Anirudh Chandrashekar¹, Ashok Handa¹, Robin Cleveland^2# and Regent Lee^2#

*, # Authors contributed equally

1. Nuffield Department of Surgical Sciences, University of Oxford
2. Department of Engineering Science, Unviersity of Oxford

Introduction

Abdominal aortic aneurysms (AAA) are associated with features of systemic inflammation and endothelial dysfunction. Flow mediated dilatation (FMD), measured remotely at the brachial artery, is a recognised non-invasive measurement for endothelial function. We had previously reported FMD to be a predictor of AAA growth. We hypothesised that other physical characteristics of the brachial artery wall correlate with AAA growth.

Methods

In a prospectively recruited cohort of patients with AAAs (Oxford Abdominal Aortic Aneurysm Study), brachial wall motion captured from ultrasound data was analysed. We developed a novel image analysis method (UK patent priority filing P255395GB) to extract a ‘brachial artery relaxation index’ (BARI), and examined BARI in the context of AAA and its correlation with future aneurysm growth.

Results

Preliminary results were promising with clear differentiation between patients at the extreme spectrum of prospective AAA growth. However, there was no difference in BARI between age and sex matched healthy volunteers and OxAAA patients (n=15 each, p=0.77). In the entire OxAAA Study cohort (n=126) no differences was observed in BARI between aneurysms of different diameters (30-40mm vs 40-55mm vs >55mm, ANOVA p=0.99). Furthermore, no correlation between BARI and future aneurysm growth was observed (p=0.5).

Discussion

Image based analyses of vasculature is important in the context of AAAs. We developed a novel analysis method to extract characteristics of arterial wall motion as a proposed biomarker and tested its utility in the context of AAA disease. This serves as a model for future collaborative research in an inter-disciplinary approach.