Ultrasound low-velocity flow estimations using cross-correlation and decorrelation: A thread phantom study

In this paper, two time-domain flow velocity measurement methods, cross-correlation and decorrelation, were implemented and compared in measuring low blood-flow velocities, ranging from 0.05 to 5 cm/s, at known beam-vessel angles of 50–90° in a thread phantom. Both methods achieved a significant correlation between the measured and the known velocities (r = 0.99; P < 0.001) in the thread phantom measurements, at 50–70° beam-vessel angles. Although the cross-correlation method showed a significant correlation (r > 0.99; P < 0.001), this method caused large errors (>45%) at 80° and 90°, whereas the decorrelation method not only achieved a significant correlation (r > 0.99; P < 0.001) but also resulted in smaller errors (<19%) at 80° and 90°. This study demonstrates the potential of time-domain decorrelation method for measuring low flow velocity at large beam-vessel angles near perpendicular conditions.