Flow Residence Time and Regions of Intraluminal Thrombus Deposition in Intracranial Aneurysms

• Published in: Annals of biomedical engineering Vol. 38; no. 10; pp. 3058 - 3069
• Main Authors: Rayz, V. L, Boussel, L, Ge, L, Leach, J. R, Martin, A. J, Lawton, M. T, McCulloch, C, Saloner, D
• Format: Journal Article
• Language: English
• Published: Boston Boston : Springer US 01.10.2010; Springer US; Springer Nature B.V
• Subjects: Biochemistry; Biological and Medical Physics; Biomedical and Life Sciences; Biomedical Engineering and Bioengineering; Biomedicine; Biophysics; Blood Flow Velocity; Classical Mechanics; Computational fluid dynamics; Flow separation regions; Humans; Imaging, Three-Dimensional; Intra-aneurysmal thrombus; Intracranial Aneurysm - pathology; Intracranial Aneurysm - physiopathology; Magnetic Resonance Angiography - methods; magnetic resonance imaging; Models, Cardiovascular; Thrombosis - pathology; Thrombosis - physiopathology; Flow separation regions; Intra-aneurysmal thrombus; Computational fluid dynamics; Magnetic resonance imaging
• ISSN: 0090-6964; 1573-9686
• DOI: 10.1007/s10439-010-0065-8

Thrombus formation in intracranial aneurysms, while sometimes stabilizing lesion growth, can present additional risk of thrombo-embolism. The role of hemodynamics in the progression of aneurysmal disease can be elucidated by patient-specific computational modeling. In our previous work, patient-specific computational fluid dynamics (CFD) models were constructed from MRI data for three patients who had fusiform basilar aneurysms that were thrombus-free and then proceeded to develop intraluminal thrombus. In this study, we investigated the effect of increased flow residence time (RT) by modeling passive scalar advection in the same aneurysmal geometries. Non-Newtonian pulsatile flow simulations were carried out in base-line geometries and a new postprocessing technique, referred to as “virtual ink” and based on the passive scalar distribution maps, was used to visualize the flow and estimate the flow RT. The virtual ink technique clearly depicted regions of flow separation. The flow RT at different locations adjacent to aneurysmal walls was calculated as the time the virtual ink scalar remained above a threshold value. The RT values obtained in different areas were then correlated with the location of intra-aneurysmal thrombus observed at a follow-up MR study. For each patient, the wall shear stress (WSS) distribution was also obtained from CFD simulations and correlated with thrombus location. The correlation analysis determined a significant relationship between regions where CFD predicted either an increased RT or low WSS and the regions where thrombus deposition was observed to occur in vivo. A model including both low WSS and increased RT predicted thrombus-prone regions significantly better than the models with RT or WSS alone.