Thursday, October 10, 2013

Paper accepted, Am J Neuroradiol

I never know what is the embargo policy for specific journals, but since the printer has delayed the processing of our paper (accepted almost three months ago), I think it's fair that we share the good/bad news about a study led by BSL postdoc Kristian Valen-Sendstad, entitled: "Mind the gap: Impact of CFD solution strategy on prediction of intracranial aneurysm hemodynamics and rupture status indicators".  Here's the abstract, paper (hopefully) coming soon:

Background and Purpose: Computational fluid dynamics (CFD) has become a popular tool for studying intracranial aneurysm hemodynamics, demonstrating success for retrospectively discriminating rupture status; however, recent highly-refined simulations suggest potential deficiencies in solution strategies normally employed in the aneurysm CFD literature. The purpose of the present study was to determine the impact of this gap.
Materials and Methods: Pulsatile flow in 12 realistic MCA aneurysms was simulated using both high resolution (HR) and normal resolution (NR) strategies. Velocity fields were compared at selected instants via domain-averaged error. Wall shear stress (WSS) fields and various reduced hemodynamic indices were also compared: cycle-averaged mean and maximum WSS; oscillatory shear index (OSI); low shear area (LSA); viscous dissipation ratio (VDR); kinetic energy ratio (KER).
Results: Instantaneous differences in flow and WSS patterns were appreciable, especially for bifurcation aneurysms. Linear regressions revealed strong correlations (R2>0.9) between HR and NR solutions for all indices but KER (R2=0.25) and OSI (R2=0.23); however, for most indices the slopes were significantly less than one, reflecting a pronounced underestimation by the NR simulations. Some HR simulations were highly unstable with fluctuating WSS, reflected by the poor OSI correlation.
Conclusion: Typical CFD solution strategies may ultimately be adequate for augmenting rupture risk assessment based on certain highly-reduced indices; however, they cannot be relied upon for predicting the magnitude and character of the complex biomechanical stimuli to which the aneurysm wall may be exposed. This impact of CFD solution strategy is likely greater than that for other modelling assumptions or uncertainties.

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