Article Figures & Data
Figures
- Fig 1.
A representative phantom study demonstrates the flow calculation from 4D-DSA. A, MIP image of the reconstructed phantom with centerline (red) overlaid. B, The contrast waveform map of the voxels along the centerline. The horizontal direction is the timeframe in the 4D-DSA scan, and the vertical direction is the position along the vessel centerline. Each point in the map M(t,z) represents the signal intensity of the voxel at distance z along the centerline and at time frame t. The highlighted area is the optimized waveform region where the pulsatility is strong and consistent. TCCs of 2 selected voxels along the centerline (marked as blue and red stars on A and blue and red curves on B) are shown in C. D, The least-squares differences of these 2 signals as a function of the time-shift, in which the minimal appears at τ0 = 5 shown as red arrow on D is considered as the time of bolus transport from the blue voxel to the red voxel. The time-shift as a function of the centerline position was fit to a linear relation (F), where the slope is the inverse of the velocity. E, The flow profile recorded from the flow probe (downsampled to 1/30 second to correspond to the 4D-DSA timeframes). Flow measurement is the average taken between the red lines, which correspond to the optimized window shown in B. AUI indicates arbitrary unit of intensity.
- Fig 2.
Linear regression between the flow probe measurements and the 4D-DSA calculations from 15 phantom studies. Evaluations have been obtained with significance levels P = 4.521E-11 for the slope and P = 0.18 for the intercept.
- Fig 3.
A representative ICA study. A, The centerline positions of the ICA. B, The contrast waveform map of the voxels along the centerline. The highlighted area is the optimized waveform region for the flow calculation. C, The time-shift as a function of the centerline position was fit to a linear relation in which the slope is the inverse of the velocity.
- Fig 4.
Correlation analysis between velocity estimated from 4D-DSA and measured using PC VIPR. The significance level is P = .0002.
- Fig 5.
Bland-Altman analysis of 4D-DSA compared with PC VIPR.
- Fig 6.
Fluctuation of the velocity estimation with a different average range. A, The flow profile recorded from the flow probe. Red lines define the starting average window. This window was gradually expanded to the purple line. The corresponding mean velocity was shown as the blue curve. A zoom-in of the green window is shown in B. Similarly, velocity calculations have been performed by gradually expanding the window coverage from yellow to purple as shown in the waveform map (C). Estimated velocity varies (D) as the window edge slides from position A toward B. AU indicates arbitrary units.
