Flow characteristics in a canine aneurysm model: A comparison of 4D accelerated phase‐contrast MR measurements and computational fluid dynamics simulations

Abstract

Purpose: 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.

Inflow Jet Patterns of Unruptured Cerebral Aneurysms Based on the Flow Velocity in the Parent Artery: Evaluation Using 4D Flow MRI

“…10-20 The hemodynamics (eg, the velocity distribution, inflow streamlines, and flow patterns) determined on 4D flow MR imaging have been validated by computational fluid dynamics studies in human cerebral aneurysms, 10,12,14 experimental canine aneurysms, 25 and life-size human aneurysm phantoms. 22,26,27 The feasibility of visualizing the aneurysmal inflow on 4D flow MR imaging has been confirmed.…”

“…4D flow MR imaging may yield poor-quality images due to motion artifacts attributable to a relatively long acquisition time 21 and limited spatial resolution. [9][10][11][12][13][14]17,20,22,[25][26][27] Because flow quantification by using 4D flow MR imaging requires at least 16 isotropic voxels over the vessel lumen area, 31 a spatial resolution of 1.0 mm in the isotropic voxel dimensions is needed to evaluate the flow conditions in aneurysms with a diameter of 4.0 mm. 22 Although only 1.5T MR imaging scanners are available at our institution, high-resolution MR imaging on greater than 3T instruments may make it possible to evaluate the inflow jets of aneurysms smaller than 4.0 mm.…”

Identification of the Inflow Zone of Unruptured Cerebral Aneurysms: Comparison of 4D Flow MRI and 3D TOF MRA Data

“…18,19 Both 4D flow MR imaging and computational fluid dynamics studies, used to evaluate the hemodynamics of cerebral aneurysms, returned similar results with respect to velocity distributions, inflow streamlines, and intraaneurysmal flow patterns in human cerebral 19,21,23 and experimental canine aneurysms. 36 In addition, 4D flow MR imaging results were validated by computational fluid dynamics studies performed on a life-size human aneurysm phantom. [37][38][39] Moreover, previous studies confirmed the feasibility of depicting the aneurysmal inflow.…”

3D Cine Phase-Contrast MRI at 3T in Intracranial Aneurysms Compared with Patient-Specific Computational Fluid Dynamics

“…29 Another study compared 3D PC-MR imaging with CFD in canine aneurysm models. 30 All studies found a good qualitative agreement between both techniques and a moderate quantitative agreement. Note that the purpose of the CFD simulations in this study was to compare the results with the 3D PC-MR imaging measurements.…”