RT Journal Article
SR Electronic
T1 How patient-specific do internal carotid artery inflow rates need to be for computational fluid dynamics of cerebral aneurysms?
JF Journal of NeuroInterventional Surgery
JO J NeuroIntervent Surg
FD BMJ Publishing Group Ltd.
SP neurintsurg-2020-015993
DO 10.1136/neurintsurg-2020-015993
A1 Mehdi Najafi
A1 Nicole M Cancelliere
A1 Olivier Brina
A1 Pierre Bouillot
A1 Maria I Vargas
A1 Benedicte MA Delattre
A1 Vitor M Pereira
A1 David A Steinman
YR 2020
UL http://jnis.bmj.com/content/early/2020/07/30/neurintsurg-2020-015993.abstract
AB Background Computational fluid dynamics (CFD) has become a popular tool for studying ‘patient-specific’ blood flow dynamics in cerebral aneurysms; however, rarely are the inflow boundary conditions patient-specific. We aimed to test the impact of widespread reliance on generalized inflow rates.Methods Internal carotid artery (ICA) flow rates were measured via 2D cine phase-contrast MRI for 24 patients scheduled for endovascular therapy of an ICA aneurysm. CFD models were constructed from 3D rotational angiography, and pulsatile inflow rates imposed as measured by MRI or estimated using an average older-adult ICA flow waveform shape scaled by a cycle-average flow rate (Qavg) derived from the patient’s ICA cross-sectional area via an assumed inlet velocity.Results There was good overall qualitative agreement in the magnitudes and spatial distributions of time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and spectral power index (SPI) using generalized versus patient-specific inflows. Sac-averaged quantities showed moderate to good correlations: R2=0.54 (TAWSS), 0.80 (OSI), and 0.68 (SPI). Using patient-specific Qavg to scale the generalized waveform shape resulted in near-perfect agreement for TAWSS, and reduced bias, but not scatter, for SPI. Patient-specific waveform had an impact only on OSI correlations, which improved to R2=0.93.Conclusions Aneurysm CFD demonstrates the ability to stratify cases by nominal hemodynamic ‘risk’ factors when employing an age- and vascular-territory-specific recipe for generalized inflow rates. Qavg has a greater influence than waveform shape, suggesting some improvement could be achieved by including measurement of patient-specific Qavg into aneurysm imaging protocols.