Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Effect of Inlet Velocity Profiles on Patient-Specific Computational Fluid Dynamics Simulations of the Carotid Bifurcation J Biomech Eng. 2012;134(5): doi: / Snapshot at peak systole of the four inlet velocity profiles prescribed at the common carotid artery (CCA). The real measured velocity profile (top left) was derived from direct phase-contrast magnetic resonance (PCMR) imaging of a patient over the cardiac cycle. The volume flow rate of this “reference standard” velocity profile was then used to compute the blunt (top right), Womersley (bottom left), and parabolic (bottom right) velocity profiles. Data is from subject #4. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Effect of Inlet Velocity Profiles on Patient-Specific Computational Fluid Dynamics Simulations of the Carotid Bifurcation J Biomech Eng. 2012;134(5): doi: / On the reconstructed 3D geometry, centerlines along the carotid bifurcation were detected using VMTK software (a), and split into branches (b). Angular metric (c), and distance along the centerline were used to map OSI and time-averaged WSS distributions (d) in the internal carotid artery onto a flat surface to create a “virtual enface” view of hemodynamics (see Fig. ). Data is from subject #4. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Effect of Inlet Velocity Profiles on Patient-Specific Computational Fluid Dynamics Simulations of the Carotid Bifurcation J Biomech Eng. 2012;134(5): doi: / Oscillatory shear index (OSI) in the carotid bulb varies in magnitude and distribution among CFD simulations employing four different inlet velocity profiles. Data is from subject #4. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Effect of Inlet Velocity Profiles on Patient-Specific Computational Fluid Dynamics Simulations of the Carotid Bifurcation J Biomech Eng. 2012;134(5): doi: / Using VMTK software, we mapped hemodynamic parameters from a 3D model (see Fig. ) into the 2D plane using the techniques in Fig.. We analyzed the internal carotid artery around the carotid bulb and investigated the magnitude and distribution of the mean WSS (left) and OSI (right) under varying inlet velocity profile conditions. Mean WSS magnitudes are more affected by inlet conditions than distribution, while OSI distributions are relatively more affected by inlet conditions than magnitude. Data is from subject #5. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Effect of Inlet Velocity Profiles on Patient-Specific Computational Fluid Dynamics Simulations of the Carotid Bifurcation J Biomech Eng. 2012;134(5): doi: / Extracting axial profiles of mean WSS results in the ICA allows for the visualization and quantification of spatial and magnitude differences in the mean WSS resulting from different inlet velocity profiles. Profiles aligned with the inner and outer ridge of the ICA (yellow axial line, in 3D at left, and brown [inner, at −π/2] and green [outer, at +π/2] lines in virtual en face at top right) can be compared visually (bottom right) and using the intra-class correlation coefficient (see Fig. ). Patient-specific CFD allows researchers to study how local minima and maxima of the WSS vary spatially, but the inlet flow profile influences this distribution. Data is from subject #9. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Effect of Inlet Velocity Profiles on Patient-Specific Computational Fluid Dynamics Simulations of the Carotid Bifurcation J Biomech Eng. 2012;134(5): doi: / Pointwise percent difference of results from simulations using different inlet velocity profiles. The choice of inlet flow conditions affects the WSS and OSI calculations, but not as much as the natural anatomic variation among patients or the use of a non-subject- specific flow waveform to compute the velocity profiles. Error bars shown are standard deviation, and * indicates p < 0.002, relative to other inlet velocity profiles. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Effect of Inlet Velocity Profiles on Patient-Specific Computational Fluid Dynamics Simulations of the Carotid Bifurcation J Biomech Eng. 2012;134(5): doi: / Intraclass correlation coefficient (ICC) calculated between axial profiles of the mean WSS extracted from the inside and outside ridges of the internal carotid artery (ICA), as in Fig.. On average, results from the simulations using the parabolic velocity profile show the highest correlation to results from simulations using the real measured velocity profile, while the ICC among subjects and between simulations using velocity profiles derived from non-subject-specific flow waveforms have a lower correlation, demonstrating the strong importance of patient anatomy and individual flow waveforms when performing computational fluid dynamics. Figure Legend: