Predicting the Risk of Rupture of Abdominal Aortic Aneurysms by Utilizing Various Geometrical Parameters: Revisiting the Diameter Criterion

Abstract

The authors estimated noninvasively the wall stress distribution for actual abdominal aortic aneurysms (AAAs) in vivo on a patient-to-patient basis and correlated the peak wall stress (PWS) with various geometrical parameters. They studied 39 patients (37 men, mean age 73.7 +/- 8.2 years) with an intact AAA (mean diameter 6.3 +/- 1.7 cm) undergoing preoperative evaluation with spiral computed tomography (CT). Real 3-dimensional AAA geometry was obtained from image processing. Wall stress was determined by using a finite-element analysis. The aorta was considered isotropic with linear material properties and was loaded with a static pressure of 120.0 mm Hg. Various geometrical parameters were used to characterize the AAAs. PWS and each of the geometrical characteristics were correlated by use of Pearson's rank correlation coefficients. PWS varied from 10.2 to 65.8 N/cm2 (mean value 37.1 +/- 9.9 N/cm2). Among the geometrical parameters, the PWS was well correlated with the mean centerline curvature, the maximum centerline curvature, and the maximum centerline torsion of the AAAs. The correlation of PWS with maximum diameter was nonsignificant. Multiple regression analysis revealed that the mean centerline curvature of the AAA was the only significant predictor of PWS and subsequent rupture risk. This noninvasive computational approach showed that geometrical parameters other than the maximum diameter are better indicators of AAA rupture.

Computational Growth and Remodeling of Abdominal Aortic Aneurysms Constrained by the Spine

“…As a result the AAA, which commonly does not rupture in the supported region, usually ruptures in the posterolateral sites due to the retroperitoneal cavity [1]. On the other hand, higher surface curvature [53] and centerline asymmetry [54] have been associated with higher wall stress. Patient-specific aneurysm models were shown to rupture mostly at regions of high stress (inflection regions) [36,55] which were not necessarily the regions of lowest wall thickness.…”

Predictors of Abdominal Aortic Aneurysm (AAA) Growth and AAA Rupture Risk Besides AAA Size: Fact or Fiction?

“…27 Circulating levels of several markers of extracellular matrix degeneration with biological plausibility have been correlated with AAA progression, such as elastin peptides, aminoterminal propeptide of type III procollagen, elastase-a1-antitrypsin complexes, matrix metalloproteinase 9, cystatin C, plasmin-antiplasmin complexes, and tissue plasminogen activator. 27 Others supported that a quantitative 3-dimensional tortuosity index of the AAA shape 28 or the peak wall stress and the mean centerline curvature of the AAA 29 may be better predictors of the AAA rupture potential than AAA size. Although promising results have been reported, no definite conclusions can be drawn yet.…”

Pathopysiology of Abdominal Aortic Aneurysm Rupture and Expansion: New Insight on an Old Problem

“…Advanced patient-specific computational models can be used to assess the correlation between PWS and 3D geometric features. Giannoglou et al (Giannoglou et al, 2006) reported a strong relationship between PWS values and the centerline curvature in AAA models, whereas Doyle et al (Doyle et al, 2010) advocated a correlation between PWS and centerline asymmetry. Both studies were based on computational models without taking into account the presence of thrombus.…”