title: Influence of the Accuracy of Angiography-Based Reconstructions on Velocity and Wall Shear Stress Computations in Coronary Bifurcations: A Phantom Study.
abstract: BACKGROUND
  Wall shear stress (WSS) plays a key role in the onset and progression of atherosclerosis in human coronary arteries. Especially sites with low and oscillating WSS near bifurcations have a higher propensity to develop atherosclerosis. WSS computations in coronary bifurcations can be performed in angiography-based 3D reconstructions. It is essential to evaluate how reconstruction errors influence WSS computations in mildly-diseased coronary bifurcations. In mildly-diseased lesions WSS could potentially provide more insight in plaque progression.
  
  
  METHODS
  Four Plexiglas phantom models of coronary bifurcations were imaged with bi-plane angiography. The lumens were segmented by two clinically experienced readers. Based on the segmentations 3D models were generated. This resulted in three models per phantom: one gold-standard from the phantom model itself, and one from each reader. Steady-state and transient simulations were performed with computational fluid dynamics to compute the WSS. A similarity index and a noninferiority test were used to compare the WSS in the phantoms and their reconstructions. The margin for this test was based on the resolution constraints of angiography.
  
  
  RESULTS
  The reconstruction errors were similar to previously reported data; in seven out of eight reconstructions less than 0.10 mm. WSS in the regions proximal and far distal of the stenosis showed a good agreement. However, the low WSS areas directly distal of the stenosis showed some disagreement between the phantoms and the readers. This was due to small deviations in the reconstruction of the stenosis that caused differences in the resulting jet, and consequently the size and location of the low WSS area.
  
  
  CONCLUSIONS
  This study showed that WSS can accurately be computed within angiography-based 3D reconstructions of coronary arteries with early stage atherosclerosis. Qualitatively, there was a good agreement between the phantoms and the readers. Quantitatively, the low WSS regions directly distal to the stenosis were sensitive to small reconstruction errors.
authors.affiliation: Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Jelle T C
authors.initials: JT
authors.lastname: Schrauwen
authors.affiliation: Department of Cardiology, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Antonios
authors.initials: A
authors.lastname: Karanasos
authors.affiliation: Department of Cardiology, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Nienke S
authors.initials: NS
authors.lastname: van Ditzhuijzen
authors.affiliation: Pie Medical Imaging, Maastricht, the Netherlands.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Aben
authors.affiliation: Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands.|Department of Imaging Physics, Delft University of Technology, Delft, the Netherlands.
authors.forename: Antonius F W
authors.initials: AF
authors.lastname: van der Steen
authors.affiliation: Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Jolanda J
authors.initials: JJ
authors.lastname: Wentzel
authors.affiliation: Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Frank J H
authors.initials: FJ
authors.lastname: Gijsen
mesh_terms: D001783:Blood Flow Velocity; D003198:Computer Simulation; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008955:Models, Cardiovascular; D019047:Phantoms, Imaging; D033081:Shear Strength