Medical & Biological Engineering & Computing

, Volume 49, Issue 8, pp 891–899 | Cite as

Timing and size of flow impingement in a giant intracranial aneurysm at the internal carotid artery

  • Liang-Der JouEmail author
  • Michel E. Mawad
Original Article


Flow impingement is regarded as a key factor for aneurysm formation and rupture. Wall shear stress (WSS) is often used to evaluate flow impingement even though WSS and impinging force are in two different directions; therefore, this raises an important question of whether using WSS for evaluation of flow impingement size is appropriate. Flow impinging behavior in a patient-specific model of a giant aneurysm (GA) at the internal carotid artery (ICA) was analyzed by computational fluid dynamics simulations. An Impingement Index (IMI) was used to evaluate the timing and size of flow impingement. In theory, the IMI is related to the WSS gradient, which is known to affect vascular biology of endothelial cells. Effect of non-Newtonian fluid, aneurysm size, and heart rate were also studied. Maximum WSS is found to be proportional to the IMI, but the area of high wall shear is not proportional to the size of impingement. A faster heart rate or larger aneurysm does not produce a larger impinging site, and the Newtonian assumption overestimates the size of impingement. Flow impingement at the dome occurs approximately 0.11 s after the peak of flow waveform is attained. This time delay also increases with aneurysm size and varies with heart rate and waveform.


Aneurysm Intracranial aneurysm Blood flow 


Conflict of interests

The authors declare that they have no conflict of interests.

Supplementary material

Supplementary material 1. Simulation of velocity contour during a cardiac cycle (MPG 518 kb)

11517_2010_727_MOESM2_ESM.mpg (1 mb)
Supplementary material 2. Fluoroscopy of the giant aneurysm at 7.5 frames/s (MPG 1064 kb)


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Copyright information

© International Federation for Medical and Biological Engineering 2011

Authors and Affiliations

  1. 1.Department of Radiology, MS-360Baylor College of MedicineHoustonUSA

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