Analysis of hemodynamics and aneurysm occlusion after flow-diverting treatment in rabbit models.
OBJECTIVE
Predicting the outcome of flow diversion treatment of cerebral aneurysms remains challenging. Our aim was to investigate the relationship between hemodynamic conditions created immediately after flow diversion and subsequent occlusion of experimental aneurysms in rabbits.


METHODS
The hemodynamic environment before and after flow-diversion treatment of elastase-induced aneurysms in 20 rabbits was modeled by using image-based computational fluid dynamics. Local aneurysm occlusion was quantified by using a voxelization technique on 3D images acquired 8 weeks after treatment. Global and local voxel-by-voxel hemodynamic variables were used to statistically compare aneurysm regions that later thrombosed to regions that remained patent.


RESULTS
Six aneurysms remained patent at 8 weeks, while 14 were completely or nearly completely occluded. Patent aneurysms had statistically larger neck sizes (P = .0015) and smaller mean transit times (P = .02). The velocity, vorticity, and shear rate were approximately 2.8 times (P < .0001) larger in patent regions-that is, they had larger "flow activity" than regions that progressed to occlusion. Statistical models based on local hemodynamic variables were capable of predicting local occlusion with good precision (84% accuracy), especially away from the neck (92%-94%). Predictions near the neck were poorer (73% accuracy).


CONCLUSIONS
These results suggests that the dominant healing mechanism of occlusion within the aneurysm dome is related to slow-flow-induced thrombosis, while near the neck, other processes could be at play simultaneously.
From the Center for Computational Fluid Dynamics (J.R.C., F.M., M.R.), College of Sciences, George Mason University, Fairfax, Virginia jcebral@gmu.edu.
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JR
Cebral
From the Center for Computational Fluid Dynamics (J.R.C., F.M., M.R.), College of Sciences, George Mason University, Fairfax, Virginia.
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F
Mut
From the Center for Computational Fluid Dynamics (J.R.C., F.M., M.R.), College of Sciences, George Mason University, Fairfax, Virginia.
M
M
Raschi
Departments of Radiology (S.H., Y.-H.D., B.J.E., R.K., D.F.K.).
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S
Hodis
Departments of Radiology (S.H., Y.-H.D., B.J.E., R.K., D.F.K.).
Y-H
YH
Ding
Departments of Radiology (S.H., Y.-H.D., B.J.E., R.K., D.F.K.).
B J
BJ
Erickson
Departments of Radiology (S.H., Y.-H.D., B.J.E., R.K., D.F.K.).
R
R
Kadirvel
Departments of Radiology (S.H., Y.-H.D., B.J.E., R.K., D.F.K.)Neurosurgery (D.F.K.), Mayo Clinic, Rochester, Minnesota.
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DF
Kallmes
D000818:Animals; D004195:Disease Models, Animal; D006439:Hemodynamics / Q000502:physiology*; D057446:Hydrodynamics; D021621:Imaging, Three-Dimensional; D002532:Intracranial Aneurysm / Q000628:therapy*; D011817:Rabbits; D015607:Stents