Article Figures & Data
Figures
- Fig 1.
2D representation of the segmentation procedure. Dashed lines represent the vessel lumen; yellow pixels are the segmentation result. White pixels represent pixel intensity of ≥18%. Dark pixel is the user-defined reference pixel whose velocity direction was used to label a segment of length l. Segmentation was not updated between cardiac frames. Typical segmentations of the ICA, basilar artery, MCA, and ACA contained 230, 110, 80, and 60 pixels, respectively.
- Fig 2.
Maximum intensity projection image. Colored sections show segmentations produced for comparison with the 2D PCMRI data.
- Fig 3.
Arterial hemodynamics provided from a 4D PCMRI quantification. A, Flow curves for vessels evaluated in this study. The right ICA, MCA, and ACA are shown. Cardiac phase 1–20 represents the time positions in the cardiac cycle of the reconstructed frames. B, ICA ΔV calculation. Subtraction of net flow and calculation of the cumulative integral on the remaining waveform yield the cyclic volume variation of downstream arteries required to convert the pulsatile right ICA waveform to a nonpulsatile capillary flow. ICA ΔV was defined as the maximum minus minimum of this volume variation.
- Fig 4.
Correlation between 4D and 2D PCMRI quantifications of pulsatility and net flow. A, ΔV quantifications for all vessels. B, ΔV quantifications, excluding measurements with large differences in heart rate. C, Net flow quantifications for all vessels. D, Net flow quantifications, excluding measurements with large differences in heart rate.
- Fig 5.
Agreement between 4D and 2D PCMRI quantifications of pulsatility and net flow. Solid lines represent average difference; dashed lines represent 95% limits of agreements. The relative difference was calculated as (2D − 4D)/([2D + 4D]/2). A, ΔV quantifications for all vessels. B, ΔV quantifications, excluding measurements with large differences in heart rate. C, Net flow quantifications for all vessels. D, Net flow quantifications, excluding measurements with large differences in heart rate.
Tables
Vessel Type n ΔV 4D Mean ± SD (mL) ΔV 2D Mean ± SD (mL) Difference Mean ± SD (mL) P Value All BA 10 0.20 ± 0.08 0.21 ± 0.08 0.01 ± 0.05 .504 ICA 20 0.35 ± 0.10 0.36 ± 0.10 0.01 ± 0.06 .656 ICAa 20 0.35 ± 0.10 MCA 20 0.23 ± 0.05 0.20 ± 0.05 −0.03 ± 0.04 .006 ACA 19 0.14 ± 0.08 0.12 ± 0.08 −0.02 ± 0.05 .102 ΔHR BA 4 0.16 ± 0.07 0.17 ± 0.07 0.01 ± 0.01 .268 <5% ICA 8 0.33 ± 0.05 0.33 ± 0.05 −0.01 ± 0.03 .668 MCA 8 0.21 ± 0.04 0.20 ± 0.04 −0.02 ± 0.03 .116 ACA 11 0.14 ± 0.06 0.13 ± 0.06 −0.02 ± 0.03 .074 Note:—BA indicates basilar artery; ICA, internal carotid artery; MCA, middle cerebral artery; ACA, anterior cerebral artery; ΔHR, difference in heart rate; ΔV, volume of arterial pulsatility.
↵a Indicates proximal ICA measurement for internal consistency analyses.
Vessel Type n Net Flow 4D Mean ± SD (mL/s) Net Flow 2D Mean ± SD (mL/s) Difference Mean ± SD (mL/s) P Value All BA 10 2.15 ± 0.58 2.18 ± 0.49 0.03 ± 0.34 .787 ICA 20 3.72 ± 0.70 4.02 ± 0.62 0.29 ± 0.40 .004 ICAa 20 3.81 ± 0.71 MCA 20 2.54 ± 0.36 2.26 ± 0.34 −0.28 ± 0.29 <.001 ACA 19 1.47 ± 0.52 1.44 ± 0.49 −0.02 ± 0.21 .627 ΔHR BA 4 2.16 ± 0.89 2.02 ± 0.74 −0.13 ± 0.39 .538 <5% ICA 8 4.04 ± 0.51 4.32 ± 0.51 0.28 ± 0.43 .108 MCA 8 2.58 ± 0.27 2.46 ± 0.42 −0.12 ± 0.23 .173 ACA 11 1.55 ± 0.61 1.49 ± 0.61 −0.06 ± 0.26 .427 Note:—BA indicates basilar artery; ICA, internal carotid artery; MCA, middle cerebral artery; ACA, anterior cerebral artery; ΔHR, difference in heart rate; ΔV, volume of arterial pulsatility.
↵a Indicates proximal ICA measurement for internal consistency analyses.
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