Changes in Aortic Diameter and Wall Strain in Progressing Abdominal Aortic Aneurysms

Objectives: The analysis of wall strain opens new perspectives in the prediction of abdominal aortic aneurysm (AAA) rupture. This study investigates the capability of four-dimensional ultrasound (4D US) to detect and characterize changes in wall strain in the same patients during follow-up observations.

Methods: Eighteen patients were examined by 64 4D US scans during a median follow-up period of 24.5 months. After performing the 4D US and manual aneurysm segmentation, kinematic analysis was performed using a customized interface and evaluation of the mean and peak circumferential strain, as well as spatial heterogeneity.

Results: All aneurysms showed a continuous diameter growth with a mean rate of 4% per year (P < .001). The mean circumferential strain (MCS) tends to increase from a median 0.89% by 10.49% per year in follow-up independent of the aneurysm diameter (P = .063). The subgroup analysis reveals a cohort with increasing MCS and decreasing spatial heterogeneity, as well as a cohort with nonincreasing MCS and increasing spatial heterogeneity (P < .05).

Conclusions: The 4D US is able to register the strain changes in AAA follow-up. The MCS tends to increase during the observation time in the entire cohort, but the changes were independent of the maximum aneurysm diameter. The kinematic parameters allow the entire AAA cohort to differentiate into two subgroups and provide additional information about the pathologic behavior of the aneurysm wall.