%0 Journal Article %A Y. Wu %A G. Shaughnessy %A C.A. Hoffman %A E.L. Oberstar %A S. Schafer %A T. Schubert %A K.L. Ruedinger %A B.J. Davis %A C.A. Mistretta %A C.M. Strother %A M.A. Speidel %T Quantification of Blood Velocity with 4D Digital Subtraction Angiography Using the Shifted Least-Squares Method %D 2018 %R 10.3174/ajnr.A5793 %J American Journal of Neuroradiology %X 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 %U https://www.ajnr.org/content/ajnr/early/2018/09/13/ajnr.A5793.full.pdf