Sensitivity of patient-specific numerical simulation of cerebal aneurysm hemodynamics to inflow boundary conditions

Abstract

Measurement of the blood flow rate as well as the distribution of the flow rates in the patient's feeding arteries may be needed for numerical simulations to accurately reproduce the intraaneurysmal hemodynamics in a specific aneurysm in the clinical setting.

Mind the Gap: Impact of Computational Fluid Dynamics Solution Strategy on Prediction of Intracranial Aneurysm Hemodynamics and Rupture Status Indicators

“…The impact on hemodynamic indices was not addressed in that study, and for our HR simulations, the average element side length in the aneurysm sac was 0.06 mm, well below the 0.08 mm reported for the converged solutions of Hodis et al 8 The pronounced impact of the CFD solution strategy on the magnitude of derived hemodynamic indices implies that the solution strategy must be acknowledged as an additional source of variability, especially if and when the findings of different groups, potentially using a wide range of strategies, are compared or analyzed together. In striving for more patient-specific simulations, most studies have focused on the impact of other assumptions or uncertainties such as inflow/outflow conditions, 31 non-Newtonian rheology, 32 compliance, 33 and choice of imaging technique. 34,35 Although it is difficult to draw a direct comparison between their findings and the results of the present study, inspection of figures from those studies suggests that the qualitative differences due to those assumptions are less than the differences due to choice of CFD solution strategy as demonstrated in our study.…”

Computational Hemodynamics in Cerebral Aneurysms: The Effects of Modeled Versus Measured Boundary Conditions

“…Several authors have demonstrated the significant influence of BCs on computed hemodynamic indices. 9,19,44 Depending on the method of derivation, BCs can be broadly divided into two categories; those that are patient-specific and those that are non-patient-specific. …”

“…9,19,44 Unfortunately, these are rarely available. Of 24 articles reviewed for this study (Table 3), only 6 (25%) used patient-specific BCs.…”

“…These measurements are costly to perform, are currently rarely justifiable as part of the clinical routine and are inherently difficult to obtain for the small, intricate vessels of the cerebral vasculature hence, such studies often involve small cohorts and the results lack statistical significance. 1,19,24 Larger cohort studies, in contrast, rely on inflow BCs based on measurements taken from healthy individuals, that are, in some cases 8,23,29,35,44 scaled in an attempt to achieve a more realistic mean WSS, and outflow BCs that arbitrarily assume the same pressure at all openings (zero pressure BCs). The assumptions associated with this approach may also lead to unrealistic results.…”

Additional Value of Intra-Aneurysmal Hemodynamics in Discriminating Ruptured versus Unruptured Intracranial Aneurysms

“…Thus, high-resolution 3D geometry and patient-specific measurements of local flow velocities in the afferent artery as boundary conditions for hemodynamic simulations were used. [13][14][15] …”