title: Understanding Angiography-Based Aneurysm Flow Fields through Comparison with Computational Fluid Dynamics.
abstract: OBJECTIVE
  Hemodynamics is thought to be an important factor for aneurysm progression and rupture. Our aim was to evaluate whether flow fields reconstructed from dynamic angiography data can be used to realistically represent the main flow structures in intracranial aneurysms.
  
  
  METHODS
  DSA-based flow reconstructions, obtained during interventional treatment, were compared qualitatively with flow fields obtained from patient-specific computational fluid dynamics models and quantitatively with projections of the computational fluid dynamics fields (by computing a directional similarity of the vector fields) in 15 cerebral aneurysms.
  
  
  RESULTS
  The average similarity between the DSA and the projected computational fluid dynamics flow fields was 78% in the parent artery, while it was only 30% in the aneurysm region. Qualitatively, both the DSA and projected computational fluid dynamics flow fields captured the location of the inflow jet, the main vortex structure, the intrasaccular flow split, and the main rotation direction in approximately 60% of the cases.
  
  
  CONCLUSIONS
  Several factors affect the reconstruction of 2D flow fields from dynamic angiography sequences. The most important factors are the 3-dimensionality of the intrasaccular flow patterns and inflow jets, the alignment of the main vortex structure with the line of sight, the overlapping of surrounding vessels, and possibly frame rate undersampling. Flow visualization with DSA from >1 projection is required for understanding of the 3D intrasaccular flow patterns. Although these DSA-based flow quantification techniques do not capture swirling or secondary flows in the parent artery, they still provide a good representation of the mean axial flow and the corresponding flow rate.
authors.affiliation: From the Bioengineering Department (J.R.C., F.M., B.J.C.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia jcebral@gmu.edu.
authors.forename: J R
authors.identifier: http://orcid.org/0000-0002-3216-0856
authors.initials: JR
authors.lastname: Cebral
authors.affiliation: From the Bioengineering Department (J.R.C., F.M., B.J.C.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia.
authors.forename: F
authors.identifier: http://orcid.org/0000-0003-1907-3739
authors.initials: F
authors.lastname: Mut
authors.affiliation: From the Bioengineering Department (J.R.C., F.M., B.J.C.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia.
authors.forename: B J
authors.identifier: http://orcid.org/0000-0002-5846-7944
authors.initials: BJ
authors.lastname: Chung
authors.affiliation: Faculté de Médecine Paris-Sud (L.S.), Le Kremlin-Bicetre, France.
authors.forename: L
authors.identifier: http://orcid.org/0000-0002-6748-8528
authors.initials: L
authors.lastname: Spelle
authors.affiliation: Interventional Neuroradiology (J.M.), Beaujon University Hospital, Clichy, France.
authors.forename: J
authors.identifier: http://orcid.org/0000-0002-2086-2973
authors.initials: J
authors.lastname: Moret
authors.affiliation: Image Guided Therapy Innovation (F.v.N., D.R.), Philips Healthcare, Best, the Netherlands.
authors.forename: F
authors.identifier: http://orcid.org/0000-0001-6108-2255
authors.initials: F
authors.lastname: van Nijnatten
authors.affiliation: Image Guided Therapy Innovation (F.v.N., D.R.), Philips Healthcare, Best, the Netherlands.
authors.forename: D
authors.identifier: http://orcid.org/0000-0002-9931-4047
authors.initials: D
authors.lastname: Ruijters
mesh_terms: D002533:Cerebral Angiography / Q000379:methods*; D002560:Cerebrovascular Circulation / Q000502:physiology; D006439:Hemodynamics; D006801:Humans; D057446:Hydrodynamics; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D018810:Magnetic Resonance Angiography