Key result
A novel 40-MHz high-frequency vector Doppler imaging system measured flow velocities ranging from 2 to 15 mm/s around venous valves with a velocity estimation error of <10% in phantom studies.
Why the study?
Increasing vector Doppler imaging resolution is important for mapping superficial vessel microstructures, but vector Doppler imaging operating under high-frequency ultrasound is rare.
A newly developed 40-MHz high-frequency vector Doppler imaging system accurately estimates superficial venous flow velocities and visualizes complex flow dynamics like jets and vortices.
Supports venous hemodynamics research; Level 5 evidence leaves open clinical adoption.
PURPOSE: Doppler ultrasound imaging has been used widely for diagnosing vascular diseases. Recently, vector Doppler imaging (VDI) has been proposed for visualizing the blood flow in all directions to yield more detailed information for estimating flow conditions. Increasing the resolution of VDI is important for the structural mapping of superficial vessels with microstructure. However, VDI that operates under a high-frequency ultrasound (HFUS; >30 MHz) is rare. In this study, a 40-MHz high-frequency VDI (HFVDI) based on ultrafast ultrasound imaging was developed to obtain the vector information of blood flow around the superficial venous valve. METHODS: The use of HFUS imaging system causes an overload of data acquisition easily. In order to provide sufficient recording time, the frame rate should be reduced. Because the aliasing problem worsens due to a low frame rate when operating Doppler imaging, phase-unwrapping processing methods based on spatial and temporal continuities were applied. Flow phantom experiments were performed to validate the accuracy. In vivo experiments were performed on the valve of superficial veins of healthy volunteers. RESULTS: The experimental results from the phantom study indicated that the error of velocity estimation was <10% in most cases. Dynamic changes of valve movements and flow conditions (including velocity profiles and vector) were observed. Because of the high resolution of HFVDI, the jet and vortex phenomena were observed between the leaflets and in the sinus pocket, respectively. CONCLUSIONS: Flow velocities ranging from 2 to 15 mm/s were measured at different locations around the venous valve during the opening and closing phases. All the results indicated that HFVDI has the potential to be a useful tool for vessel duplex scanning.
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Huang et al. (2020) studied Healthy volunteers. 40-MHz high-frequency vector Doppler imaging (HFVDI) was evaluated on Velocity estimation error and flow velocity measurement. A novel 40-MHz high-frequency vector Doppler imaging system measured flow velocities ranging from 2 to 15 mm/s around venous valves with a velocity estimation error of <10% in phantom studies.
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