Quantification of Blood Velocity with 4D Digital Subtraction Angiography Using the Shifted Least-Squares Method

• Published in: American journal of neuroradiology : AJNR Vol. 39; no. 10; pp. 1871 - 1877
• Main Authors: Wu, Y., Shaughnessy, G., Hoffman, C.A., Oberstar, E.L., Schafer, S., Schubert, T., Ruedinger, K.L., Davis, B.J., Mistretta, C.A., Strother, C.M., Speidel, M.A.
• Format: Journal Article
• Language: English
• Published: United States American Society of Neuroradiology 01.10.2018
• Subjects: Adult; Angiography, Digital Subtraction - methods; Blood Flow Velocity - physiology; Carotid Artery, Internal - diagnostic imaging; Female; Humans; Imaging, Three-Dimensional - methods; Interventional; Least-Squares Analysis; Magnetic Resonance Angiography - methods; Male; Phantoms, Imaging
• ISSN: 0195-6108; 1936-959X; 1936-959X
• DOI: 10.3174/ajnr.A5793

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. 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. 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 = 0.835. The availability of 4D-DSA provides the opportunity to use the shifted least-squares method to estimate velocity in vessels within a 3D volume.