In-vivo evaluation of three ultrasound vector velocity techniques with MR angiography

In conventional Doppler ultrasound (US) the blood is only estimated along the US beam direction. The is angle corrected assuming laminar flow parallel to the oundaries. As the flow in the vascular system never is laminar, the velocities estimated with conventional US are always incorrect. Three angle independent vector methods are evaluated in this paper: directional (DB), synthetic aperture flow imaging (STA) and oscillation (TO). The performances of the three were investigated by measuring the stroke volume in the common carotid artery of eleven healthy volunteers, with resonance phase contrast angiography (MRA) as . The correlation between the three vector velocity and MRA were: DB/MRA R=0.84 (p<0.01); STA/MRA =0.95 (p<0.01); TO/MRA R=0.91 (p<0.01). Bland-Altman plots additionally constructed and mean differences for the three were: DB/MRA = 0.17 ml; STA/MRA = 0.07 ml; /MRA = 0.24 ml. The three US vector velocity techniques yield insight in to flow dynamics and can potentially give the clinician a powerful tool in cardiovascular disease assessment.