title: Feasibility of wall stress analysis of abdominal aortic aneurysms using three-dimensional ultrasound.
abstract: OBJECTIVE
  Abdominal aortic aneurysms (AAAs) are local dilations that can lead to a fatal hemorrhage when ruptured. Wall stress analysis of AAAs is a novel tool that has proven high potential to improve risk stratification. Currently, wall stress analysis of AAAs is based on computed tomography (CT) and magnetic resonance imaging; however, three-dimensional (3D) ultrasound (US) has great advantages over CT and magnetic resonance imaging in terms of costs, speed, and lack of radiation. In this study, the feasibility of 3D US as input for wall stress analysis is investigated. Second, 3D US-based wall stress analysis was compared with CT-based results.
  
  
  METHODS
  The 3D US and CT data were acquired in 12 patients (diameter, 35-90 mm). US data were segmented manually and compared with automatically acquired CT geometries by calculating the similarity index and Hausdorff distance. Wall stresses were simulated at P = 140 mm Hg and compared between both modalities.
  
  
  RESULTS
  The similarity index of US vs CT was 0.75 to 0.91 (n = 12), with a median Hausdorff distance ranging from 4.8 to 13.9 mm, with the higher values found at the proximal and distal sides of the AAA. Wall stresses were in accordance with literature, and a good agreement was found between US- and CT-based median stresses and interquartile stresses, which was confirmed by Bland-Altman and regression analysis (n = 8). Wall stresses based on US were typically higher (+23%), caused by geometric irregularities due to the registration of several 3D volumes and manual segmentation. In future work, an automated US registration and segmentation approach is the essential point of improvement before pursuing large-scale patient studies.
  
  
  CONCLUSIONS
  This study is a first step toward US-based wall stress analysis, which would be the modality of choice to monitor wall stress development over time because no ionizing radiation and contrast material are involved.
authors.affiliation: Cardiovascular Biomechanics Group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors.forename: Annette M
authors.initials: AM
authors.lastname: Kok
authors.affiliation: Department of General Surgery, Maastricht University Medical Center, Maastricht, The Netherlands; Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: V Lai
authors.initials: VL
authors.lastname: Nguyen
authors.affiliation: Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Eindhoven, The Netherlands.
authors.forename: Lambert
authors.initials: L
authors.lastname: Speelman
authors.affiliation: Esaote Europe BV, Maastricht, The Netherlands.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Brands
authors.affiliation: Department of General Surgery, Maastricht University Medical Center, Maastricht, The Netherlands; Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Geert-Willem H
authors.initials: GW
authors.lastname: Schurink
authors.affiliation: Cardiovascular Biomechanics Group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors.forename: Frans N
authors.initials: FN
authors.lastname: van de Vosse
authors.affiliation: Cardiovascular Biomechanics Group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Electronic address: r.lopata@tue.nl.
authors.forename: Richard G P
authors.initials: RG
authors.lastname: Lopata
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001019:Aortic Rupture / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005240:Feasibility Studies; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology*; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013312:Stress, Physiological; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography