Local Morphologic and Hemodynamic Analyses for the Prediction of Abdominal Aortic Aneurysm Rupture Based on Patient-Specific CTA and Computational Modeling.

Abstract

Objective: Extensive research has focused on the evaluation of rupture risks in abdominal aortic aneurysms (AAAs) through comprehensive morphologic and hemodynamic analyses, primarily considering the AAA as a whole entity. This study tried to identify the high-risk rupture sites of AAAs more precisely before the fatal process based on morphologic and hemodynamic analyses at the local segment.

Methods: Computed tomography angiography of a specific AAA patient was conducted at the follow-up 4 months before rupture, 1 day before rupture, the day of the rupture, and 15 days after endovascular aortic repair. The evolution of local morphology and the hemodynamic characteristics at these critical timepoints were investigated based on patient-specific reconstructions and computational fluid dynamics.

Results: The morphologic and hemodynamic parameters of the rupture region vary continuously in the process of AAA development and rupture. The surface area and volume of the rupture segment were gradually enlarged at the follow-up 4 months before rupture (47.33 cm²; 67.35 mL), 1 day before rupture (57.23 cm²; 85.24 mL), and on the day of the rupture (62.41cm²; 104.73ml). A prominent decrease in time-averaged wall shear stress and velocity for the rupture segment is observed. The percentages of the lowest time-averaged wall shear stress (<0.1 Pa) area are increased in the AAA region (20.42%, 33.85%, and 53.00%, separately).

Conclusions: The results based on precisely rebuilt geometries for the complete follow-ups of patient-specific computed tomography angiography demonstrate that notable morphologic and hemodynamic evolutions have occurred in the local segment of the AAA, which was further proved at the rupture site. The significant changes occurring at the local segment may provide valuable information for the evaluation of aneurysm rupture risk and locate the most probable site of rupture.

Clinical impact: Capturing the entire process of AAA rupture through CTA imaging is a rare occurrence in clinical practice. The evolution of morphology and hemodynamic characteristics observed in the illustrated results provides valuable insights for clinicians to monitor the state of AAA from a different perspective. These findings suggest that variations in morphology and hemodynamics within the local segment of the AAA might serve as an alternative approach for predicting the rupture risk of AAA.