PT  - JOURNAL ARTICLE
AU  - Wu, Y.
AU  - Shaughnessy, G.
AU  - Hoffman, C.A.
AU  - Oberstar, E.L.
AU  - Schafer, S.
AU  - Schubert, T.
AU  - Ruedinger, K.L.
AU  - Davis, B.J.
AU  - Mistretta, C.A.
AU  - Strother, C.M.
AU  - Speidel, M.A.
TI  - Quantification of Blood Velocity with 4D Digital Subtraction Angiography Using the Shifted Least-Squares Method
AID  - 10.3174/ajnr.A5793
DP  - 2018 Sep 13
TA  - American Journal of Neuroradiology
4099  - http://www.ajnr.org/content/early/2018/09/13/ajnr.A5793.short
4100  - http://www.ajnr.org/content/early/2018/09/13/ajnr.A5793.full
AB  - BACKGROUND AND PURPOSE: 4D-DSA provides time-resolved 3D-DSA volumes with high temporal and spatial resolutions. The purpose of this study is to investigate a shifted least squares method to estimate the blood velocity from the 4D DSA images. Quantitative validation was performed using a flow phantom with an ultrasonic flow probe as ground truth. Quantification of blood velocity in human internal carotid arteries was compared with measurements generated from 3D phase-contrast MR imaging.MATERIALS AND METHODS: The centerlines of selected vascular segments and the time concentration curves of each voxel along the centerlines were determined from the 4D-DSA dataset. The temporal shift required to achieve a minimum difference between any point and other points along the centerline of a segment was calculated. The temporal shift as a function of centerline point position was fit to a straight line to generate the velocity. The proposed shifted least-squares method was first validated using a flow phantom study. Blood velocities were also estimated in the 14 ICAs of human subjects who had both 4D-DSA and phase-contrast MR imaging studies. Linear regression and correlation analysis were performed on both the phantom study and clinical study, respectively.RESULTS: Mean velocities of the flow phantom calculated from 4D-DSA matched very well with ultrasonic flow probe measurements with 11% relative root mean square error. Mean blood velocities of ICAs calculated from 4D-DSA correlated well with phase-contrast MR imaging measurements with Pearson correlation coefficient r = 0.835.CONCLUSIONS: The availability of 4D-DSA provides the opportunity to use the shifted least-squares method to estimate velocity in vessels within a 3D volume.PCphase-contrastSBRsideband ratioTCCtime concentration curveVIPRvastly undersampled isotropic projection reconstruction