Diagnostic Accuracy of Elastic Deformation for Detecting High Aneurysm Sac Pressure After Endovascular Aneurysm Repair

OBJECTIVES: Elastic deformation (ED) is a novel noninvasive follow-up modality after endovascular aortic repair (EVAR). ED is defined as the percentage of diameter change of the aneurysm sac after application of a controlled ultrasound transducer pressure. It is hypothesized that low aneurysm sac deformation indicates high sac pressure. The current study aims to determine the ideal cutoff value of ED and analyze the corresponding diagnostic accuracy. METHODS: A prospective cohort study was performed at a single-center tertiary university hospital. ED measurements were performed during regular follow-up in all patients after endovascular aortic repair between August 2020 and December 2024. The reference test was subsequent aneurysm sac growth. Generalized estimating equations evaluated the association between ED and aneurysm sac growth. The receiver operating characteristic curve was used to assess the discriminatory ability. RESULTS: A total of 203 ED measurements (in 100 post-EVAR patients) were analyzed. Aneurysm growth occurred in 12 patients. An odds ratio of 0.857 (95% CI 0.772-0.952) for aneurysm sac growth was calculated. The receiver operating characteristic (ROC) curve analysis revealed an area under the curve (AUC) of 0.711 (95% CI 0.587-0.836, P = 0.014). Optimal cutoff value according to the highest Youden index was estimated at 10.5% (sensitivity 92%, specificity 45%). A lower cutoff value of 6.5% also had significant discriminatory ability and was associated with higher specificity (sensitivity 58%, specificity 74%). CONCLUSION: An ultrasound-based elastic deformation (ER) of 6.5% provides a straightforward and noninvasive method to predict post-EVAR aneurysm sac growth with high specificity. Further validation, including reproducibility testing between patients and operators, is needed before clinical implementation.