RT Journal Article SR Electronic T1 Quantification of Blood Velocity with 4D Digital Subtraction Angiography Using the Shifted Least-Squares Method JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology SP 1871 OP 1877 DO 10.3174/ajnr.A5793 VO 39 IS 10 A1 Y. Wu A1 G. Shaughnessy A1 C.A. Hoffman A1 E.L. Oberstar A1 S. Schafer A1 T. Schubert A1 K.L. Ruedinger A1 B.J. Davis A1 C.A. Mistretta A1 C.M. Strother A1 M.A. Speidel YR 2018 UL http://www.ajnr.org/content/39/10/1871.abstract 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