The Two-Dimensional Shear Wave Elastography (2D-SWE) in Assessing Abdominal Aortic Wall Stiffness

Background: Ultrasound elastography, a non-invasive imaging modality, holds promise for assessing tissue stiffness, offering potential applications in the evaluation of cardiovascular disease. This study aimed to quantify local stiffness of the abdominal aortic wall using two-dimensional shear wave elastography (2D-SWE) in adults without underlying medical conditions, and to evaluate its reproducibility. Methods and Results:2D-SWE measurements of infra-renal posterior wall of the abdominal aorta (PWoAA) were obtained from 50 subjects. For intra- and inter-observer reproducibility, five 2D-SWE measurements of PWoAA were averaged, and the measurements were performed two times by observer A and once by observer B (n=750). Intraclass correlation coefficient (ICC) and Bland-Altman plot were used to establish bias and limit of agreement (LoA) between PWoAA elasticity measurements. Ultrasound 2D-SWE of PWoAA was 3.87±0.99 kPa. Intra-observer agreement of PWoAA ultrasound 2D-SWE elasticity measurements was moderate with an ICC value of 0.69 (95% CI: 0.56 – 0.82, P<0.001). Bias in intra-observer measurements was 0.18±0.92 kPa (95% LoA: -1.62 – 1.99). Similarly, inter-observer agreement was moderate with an ICC value of 0.56 (95% CI: 0.22 – 0.75, P=0.002). Bias in inter-observer measurements was -0.02±1.09 kPa (95% LoA: -2.16 – 2.11). There was no significant difference in the 2D-SWE measurements of the aortic walls, both within the same observer (mean difference [MD] 0.17, 95% CI: 0.07–0.44, P=0.16)) and between two different observers (MD=0.02, 95% CI: 0.33–0.28, P=0.86). Conclusion: Our findings demonstrated moderate reproducibility of ultrasound 2D-SWE in assessing abdominal aortic wall elasticity, with no significant differences within or between observers. Further research is warranted to optimize the clinical application of this method for assessing arterial wall stiffness, particularly in patients with cardiovascular disease, including those with abdominal aortic aneurysms.