Adaptive hybrid flow measurement of color Doppler and speckle image velocimetry.

Color Doppler (CD) ultrasound has been commonly employed in biomedical field to get hemodynamic information. However, reliable diagnostic evaluation and criteria for vascular diseases may not be provided due to technical limitations of CD, including single-directional measurement, aliasing, and limited imaging conditions. In this study, adaptive hybrid (AH) scheme is proposed to enhance measurement accuracy of conventional CD. It can improve the accuracy of velocity field measurement by replacing erroneous vectors in the measured CD results with the correct vectors obtained from a speckle image velocimetry (SIV) technique. The performance of the proposed AH technique was validated through in vitro experiments for various flow rates and insonation angle conditions, comparing conventional velocimetry techniques. The in vitro experiments demonstrated that the AH technique could measure flow velocity with better accuracy than the CD with bias errors of below 0.7 mm/s. The clinical applicability of the AH was also validated by measuring venous flows at human lower extremity, checking constant volumetric flow rates. Flow rates measured by the AH were maintained along the vein, while the CD and SIV results varied. As a result, the AH can provide improved measurement accuracy without installing a new supplementary equipment. It would be effectively utilized for analyzing flow dynamics and diagnosing valve-related disease.