Towards the Clinical utility of CFD for assessment of intracranial aneurysm rupture - a systematic review and novel parameter-ranking tool.

BACKGROUND: Intracranial aneurysms (IAs) are vascular dilations on cerebral vessels that affect between 1%-5% of the general population, and can cause life-threatening intracranial hemorrhage when ruptured. Computational fluid dynamics (CFD) has emerged as a promising tool to study IAs in recent years, particularly for rupture risk assessment. However, despite dozens of studies, CFD is still far from clinical use due to large variations and frequent contradictions in hemodynamic results between studies.

PURPOSE: To identify key gaps in the field of CFD for the study of IA rupture, and to devise a novel tool to rank parameters based on potential clinical utility.

METHODS: A Pubmed search identified 231 CFD studies for IAs. Forty-six studies fit our inclusion criteria, with a total of 2791 aneurysms. For included studies, study type, boundary conditions, solver resolutions, parameter definitions, geometric and hemodynamic parameters used, and results found were recorded.

DATA SYNTHESIS: Aspect ratio, aneurysm size, low wall shear stress area, average wall shear stress, and size ratio were the parameters that correlate most strongly with IA rupture.

LIMITATIONS: Significant differences in parameter definitions, solver spatial and temporal resolutions, number of cycles between studies as well as frequently missing information such as inlet flow rates were identified. A greater emphasis on prospective studies is also needed.

CONCLUSIONS: Our recommendations will help increase standardization and bridge the gaps in the CFD community, and expedite the process of making CFD clinically useful in guiding the treatment of IAs.