Kinematics of abdominal aortic Aneurysms

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Cardiovascular Research

Background:

• Biomechanics of Abdominal Aortic Aneurysm (AAA) is crucial for understanding disease progression.
• Existing research predominantly focuses on AAA wall stress, with limited investigation into AAA kinematics.
• AAA kinematics, including wall displacement and strain, offer significant biomechanical insights.

Purpose of the Study:

• To present an image-based, patient-specific, in vivo, and non-invasive method for AAA kinematic analysis.
• To measure AAA wall displacement and strain during the cardiac cycle using 4D-CTA.
• To compare AAA wall strain with that of a healthy aorta.

Main Methods:

• Utilized regularized deformable image registration to estimate wall displacement from 4D-CTA.
• Calculated local wall strain as the ratio of normal displacement to the local radius of curvature.
• Employed local surface fitting with non-deterministic outlier detection for radius of curvature estimation.
• Validated the approach using synthetic data from a finite element biomechanical model.

Main Results:

• Applied the method to ten patients, assessing AAA wall displacements and strains.
• Circumferential wall strain (99th percentile) ranged from 2.62% to 5.54% (average 4.45%, SD 0.87%).
• Observed significantly lower AAA wall strains compared to healthy aortic tissue.

Conclusions:

• The developed image-based approach accurately measures AAA wall displacements and enables reliable strain estimation.
• This non-invasive kinematic analysis provides valuable biomechanical insights into AAA.
• Findings highlight differences in wall strain between AAA and healthy aortas, aiding in understanding AAA pathophysiology.