Arterial secondary blood flow patterns visualized with vector flow ultrasound

This study presents the first quantification and visualization of secondary flow patterns with vector flow ultrasound. The first commercial implementation of the vector flow method Transverse Oscillation was used to obtain in-vivo, 2D vector fields in real-time. The hypothesis of this study was that the rotational direction is constant within each artery. Three data sets of 10 seconds were obtained from three main arteries in healthy volunteers. For each data set the rotational flow patterns were identified during diastole. Each data set contains a 2D vector field over time using the vector angles and velocity magnitudes the blood flow patterns were visualized using streamlines in Matlab (Mathworks, Natick, MA, USA). The rotational flow was quantified by the angular frequency for each cardiac cycle, and the mean rotational frequencies and standard deviations were calculated for the abdominal aorta {-1.3±0.4;-1.0±0.3;-0.9±0.2}Hz, the common iliac artery {-0.4±0.1;-1.0±0.2;-0.4±0.1}Hz, and the common carotid artery {0.8±0.3;1.4±0.3;0.4±0.1}Hz. A positive sign indicates an anti-clockwise rotation, and a negative sign indicates clockwise rotation. The sign of the rotational directions within each artery were constant.