Hemodynamic characterization of geometric cerebral aneurysm templates

Abstract

Hemodynamics are currently considered to a lesser degree than geometry in clinical practices for evaluating cerebral aneurysm (CA) risk and planning CA treatment. This study establishes fundamental relationships between three clinically recognized CA geometric factors and four clinically relevant hemodynamic responses. The goal of the study is to develop a more combined geometric/hemodynamic basis for informing clinical decisions. Flows within eight idealized template geometries were simulated using computational fluid dynamics and measured using particle image velocimetry under both steady and pulsatile flow conditions. The geometric factor main effects were then analyzed to quantify contributions made by the geometric factors (aneurysmal dome size (DS), dome-to-neck ratio (DNR), and parent-vessel contact angle (PV-CA)) to effects on the hemodynamic responses (aneurysmal and neck-plane root-mean-square velocity magnitude (Vrms), aneurysmal wall shear stress (WSS), and cross-neck flow (CNF)). Two anatomical aneurysm models were also examined to investigate how well the idealized findings would translate to more realistic CA geometries. DNR made the greatest contributions to effects on hemodynamics including a 75.05% contribution to aneurysmal Vrms and greater than 35% contributions to all responses. DS made the next greatest contributions, including a 43.94% contribution to CNF and greater than 20% contributions to all responses. PV-CA and several factor interactions also made contributions of greater than 10%. The anatomical aneurysm models and the most similar idealized templates demonstrated consistent hemodynamic response patterns. This study demonstrates how individual geometric factors, and combinations thereof, influence CA hemodynamics. Bridging the gap between geometry and flow in this quantitative yet practical way may have potential to improve CA evaluation and treatment criteria. Agreement among results from idealized and anatomical models further supports the potential for a template-based approach to play a useful role in clinical practice.

A non-dimensional parameter for classification of the flow in intracranial aneurysms. II. Patient-specific geometries

“…Xiang et al 26 observed high correlation between inflow pulsatility index and OSI in IAs. Nair et al 27 found dome-to-neck ratio to have the greatest impact on hemodynamics of cerebral aneurysm in comparison with other morphological parameters. Schneiders et al 28 claimed that the neck size has non-negligible effect on numerical results obtained from twenty IAs.…”

The effect of Dean, Reynolds and Womersley numbers on the flow in a spherical cavity on a curved round pipe. Part 1. Fluid mechanics in the cavity as a canonical flow representing intracranial aneurysms

“…These results differ from the observations made by Le, Borazjani & Sotiropoulos (2010), showing that Wo does not affect the flow dynamics but that the amplitude of the pulsatile inflow does. Other studies on the haemodynamics of idealized aneurysmal geometry investigated the effect of different geometrical parameters (Imai et al 2008;Nair et al 2016). More specifically, Imai et al (2008) highlighted the impact of the geometry of the parent vessel on the inflow pattern and flux, in a numerical study.…”

Efficient simulation of a low-profile visualized intraluminal support device: a novel fast virtual stenting technique

“…Over the years, a number of stent modeling techniques have been proposed that were based on an ideal aneurysm model [ 18 – 20 ]. According to previous studies, vascular and aneurysm geometries are regarded as strong factors that characterize intra-aneurysmal hemodynamics, which are closely correlated with the aneurysm’s natural history [ 21 , 22 ]. F-LVIS exhibited a benefit in fitting well with the curved vasculature, thereby boosting our confidence in the simulation.…”