Figure 1.
Vertebrobasilar configuration.
Representative vertebrobasilar configuration shown at 90-degree rotations. The direction of the flow is from the right vertebral (RV) and left vertebral (LV) arteries into the basilar artery (BAS). Anatomical orientation is labeled at the top. Since the BAS curvature direction is not preserved between subjects and the curve direction influences the flow field, the results and analysis refer to the “inner” and “outer” walls of the curve in lieu of standard anatomical directions.
Figure 2.
Vertebral artery flow waveforms.
Representative mass flow (ml/s) waveform (determined for C). Solid line: right vertebral (RV) flow; dotted line: left vertebral (LV) flow.
Figure 3.
Vertebrobasilar confluence geometries.
Vertebrobasilar system geometries of 12 healthy young adult subjects are divided into three classifications: Walking, Lambda, and Tuning Fork. In each panel, a schematic of the configuration is followed by anterior-posterior MIPs of the subject data. The two images marked with asterisks show the same subject imaged on two different days, demonstrating that the vessels retain their geometric configuration with repositioning.
Figure 4.
The time-varying vertebral artery flow ratio over the pulse cycle for the five healthy young adult subjects. Solid lines represent the ratio of right vertebral (RV) to left vertebral (LV) flow (i.e. RV/LV); dotted lines represent the ratio of LV to RV flow (i.e. LV/RV).
Table 1.
Pulse cycle characteristics.
Figure 5.
Axial velocity profiles at several axial planes along the vertebrobasilar confluence of five subject-specific models. For each model the time points shown are peak systole (left column), systolic deceleration (middle column), and diastole (right column). Colorbar representing velocity (m/s) is given for each subject.
Figure 6.
Pathlines colored by vertebral artery of origin at the CFD time point closest to peak systole for the five adult subjects at four 90-degree rotations. The orientations in the top row are applicable to all rows. Pathlines originating from the RV are yellow; those from the LV are red.
Figure 7.
Time-averaged wall shear stress distributions.
Time-averaged wall shear stress (WSS) for each vertebrobasilar system at four 90-degree rotations. The orientations and colorbar (WSS in Pa) in the top row are applicable to all rows.
Figure 8.
Oscillatory shear index contours.
Oscillatory shear index (OSI) contours for each vertebrobasilar system at four 90-degree rotations. The orientations and colorbar in the top row are applicable to all rows. For E, OSI ≤0.005; however, the model is included for completeness.