title: Patient-specific modelling of abdominal aortic aneurysms: The influence of wall thickness on predicted clinical outcomes.
abstract: Rupture of abdominal aortic aneurysms (AAAs) is linked to aneurysm morphology. This study investigates the influence of patient-specific (PS) AAA wall thickness on predicted clinical outcomes. Eight patients under surveillance for AAAs were selected from the MA(3)RS clinical trial based on the complete absence of intraluminal thrombus. Two finite element (FE) models per patient were constructed; the first incorporated variable wall thickness from CT (PS_wall), and the second employed a 1.9mm uniform wall (Uni_wall). Mean PS wall thickness across all patients was 1.77±0.42mm. Peak wall stress (PWS) for PS_wall and Uni_wall models was 0.6761±0.3406N/mm(2) and 0.4905±0.0850N/mm(2), respectively. In 4 out of 8 patients the Uni_wall underestimated stress by as much as 55%; in the remaining cases it overestimated stress by up to 40%. Rupture risk more than doubled in 3 out of 8 patients when PS_wall was considered. Wall thickness influenced the location and magnitude of PWS as well as its correlation with curvature. Furthermore, the volume of the AAA under elevated stress increased significantly in AAAs with higher rupture risk indices. This highlights the sensitivity of standard rupture risk markers to the specific wall thickness strategy employed.
authors.affiliation: Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, EH16 4TJ, UK; Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, EH16 4TJ, UK. Electronic address: noel.conlisk@ed.ac.uk.
authors.forename: Noel
authors.initials: N
authors.lastname: Conlisk
authors.affiliation: Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, EH16 4TJ, UK.
authors.forename: Arjan J
authors.initials: AJ
authors.lastname: Geers
authors.affiliation: Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, EH16 4TJ, UK.
authors.forename: Olivia M B
authors.initials: OM
authors.lastname: McBride
authors.affiliation: Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, EH16 4TJ, UK; Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, EH16 4TJ, UK.
authors.forename: David E
authors.initials: DE
authors.lastname: Newby
authors.affiliation: Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, EH16 4TJ, UK.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Hoskins
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D066230:Patient-Specific Modeling; D011379:Prognosis; D014057:Tomography, X-Ray Computed
keywords: Abdominal aortic aneurysms; Finite element analysis; Patient-specific modelling; Patient-specific wall thickness; Rupture risk