title: Flow characteristics in a canine aneurysm model: a comparison of 4D accelerated phase-contrast MR measurements and computational fluid dynamics simulations.
abstract: OBJECTIVE
  Our purpose was to compare quantitatively velocity fields in and around experimental canine aneurysms as measured using an accelerated 4D PC-MR angiography (MRA) method and calculated based on animal-specific CFD simulations.
  
  
  METHODS
  Two animals with a surgically created bifurcation aneurysm were imaged using an accelerated 4D PC-MRA method. Meshes were created based on the geometries obtained from the PC-MRA and simulations using "subject-specific" pulsatile velocity waveforms and geometries were then solved using a commercial CFD solver. Qualitative visual assessments and quantitative comparisons of the time-resolved velocity fields obtained from the PC-MRA measurements and the CFD simulations were performed using a defined similarity metric combining both angular and magnitude differences of vector fields.
  
  
  RESULTS
  PC-MRA and image-based CFD not only yielded visually consistent representations of 3D streamlines in and around both aneurysms, but also showed good agreement with regard to the spatial velocity distributions. The estimated similarity between time-resolved velocity fields from both techniques was reasonably high (mean value >0.60; one being the highest and zero being the lowest). Relative differences in inflow and outflow zones among selected planes were also reasonable (on the order of 10%-20%). The correlation between CFD-calculated and PC-MRA-measured time-averaged wall shear stresses was low (0.22 and 0.31, p < 0.001).
  
  
  CONCLUSIONS
  In two experimental canine aneurysms, PC-MRA and image-based CFD showed favorable agreement in intra-aneurismal velocity fields. Combining these two complementary techniques likely will further improve the ability to characterize and interpret the complex flow that occurs in human intracranial aneurysms.
authors: Medical Physics Department, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA. jjiang2@wisc.edu
authors: Jingfeng
authors: J
authors: Jiang
authors: Kevin
authors: K
authors: Johnson
authors: Kristian
authors: K
authors: Valen-Sendstad
authors: Kent-Andre
authors: KA
authors: Mardal
authors: Oliver
authors: O
authors: Wieben
authors: Charles
authors: C
authors: Strother
mesh_terms: D000783:Aneurysm / Q000175:diagnosis* / Q000503:physiopathology*; D000818:Animals; D003198:Computer Simulation; D004195:Disease Models, Animal; D004285:Dogs; D057446:Hydrodynamics; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008954:Models, Biological; D013314:Stress, Mechanical; D013997:Time Factors