A pull-back algorithm to determine the unloaded vascular geometry in anisotropic hyperelastic AAA passive mechanics

Area of Science:

• Biomedical Engineering
• Computational Mechanics
• Medical Imaging Analysis

Background:

• Abdominal aortic aneurysms (AAA) require accurate biomechanical analysis for surgical intervention decisions.
• Current patient-specific AAA models derived from medical images represent the artery under pressure, limiting mechanical analysis accuracy.
• Determining the zero pressure geometry is crucial for realistic assessment of AAA wall mechanics.

Purpose of the Study:

• To develop and validate a novel iterative algorithm for identifying the zero pressure geometry of patient-specific AAA models.
• To enable more accurate biomechanical estimations of AAA wall behavior.

Main Methods:

• An iterative algorithm was developed to compute the zero pressure geometry.
• The methodology incorporates anisotropic hyperelastic material properties, arterial wall thickness, and intraluminal thrombus.
• The algorithm was applied to 12 patient-specific AAA geometric models.

Main Results:

• The proposed algorithm is computationally tractable and efficient.
• The method successfully preserves the global volume of the AAA models.
• Using zero pressure geometry significantly reduces the underestimation of peak wall stress compared to CT-based geometries (59-64% lower).

Conclusions:

• The novel iterative algorithm accurately determines patient-specific AAA zero pressure geometry.
• This method enhances the reliability of biomechanical analyses for AAA, improving surgical decision-making.
• Accurate geometric and material modeling is essential for predicting AAA rupture risk.