Velocity Estimation Techniques in Flow Imaging

Velocity estimation in flow imaging encompasses a suite of methods designed to quantify the speed and direction of fluid movement within biological or engineered systems. Conventional Doppler techniques infer axial velocity from the frequency shift of backscattered ultrasound, while speckle‐tracking and phase‐based estimators measure minute displacements of tissue or tracer particles. Correlation‐based approaches, often termed ultrasound imaging velocimetry, extend particle image velocimetry concepts to ultrasound by computing full‐field velocity maps from sequential frames. More recent developments exploit plane‐wave insonification for ultrafast frame rates, enabling high‐resolution mapping of transient phenomena and wall shear stress. Advanced beamforming strategies and contrast agents further enhance sensitivity and spatial coverage. Deep learning techniques have begun to resolve aliasing and noise artefacts, broadening the dynamic range and robustness of velocity estimates. Applications span cardiovascular diagnostics, haemodynamic research and opaque flow studies, with growing emphasis on three‐dimensional and four‐dimensional volumetric assessments. The interplay between hardware innovations, signal‐processing algorithms and simulation frameworks continues to drive improvements in accuracy, temporal resolution and clinical utility.

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Velocity Estimation Techniques in Flow Imaging publication trend

The graph below shows the total number of articles in velocity estimation techniques in flow imaging across all publications each year (not limited to Nature Index journals).

Technical terms

Ultrasound Vector Flow Imaging: An angle‐independent method that combines multidirectional insonification to produce two‐dimensional velocity vector maps of blood flow.

Pulsed Wave Doppler: A classical technique measuring the axial component of flow velocity by analysing frequency shifts in pulsed ultrasound echoes.

Ultrasound Imaging Velocimetry: A correlation‐based approach that computes full‐field velocity distributions from successive ultrasound frames, analogous to optical particle image velocimetry.

Speckle Decorrelation: A displacement estimation method that tracks changes in the characteristic speckle pattern of moving scatterers to infer local velocity.

Plane‐Wave Imaging: A high‐frame‐rate ultrasound acquisition strategy that uses unfocused broad insonification to capture rapid dynamics over a large field of view.

References

1. FLUST: A fast, open source framework for ultrasound blood flow simulations. Computer Methods and Programs in Biomedicine (2023).
2. Ultrasound Imaging Velocimetry: a review. Experiments in Fluids (2016).
3. Quantitative Blood Flow Measurements in the Common Carotid Artery: A Comparative Study of High-Frame-Rate Ultrasound Vector Flow Imaging, Pulsed Wave Doppler, and Phase Contrast Magnetic Resonance Imaging. Diagnostics (2022).
4. Phase-Sensitive 2D Motion Estimators Using Frequency Spectra of Ultrasonic Echoes. Applied Sciences (2016).
5. 3-D Velocity and Volume Flow Measurement $In~Vivo$ Using Speckle Decorrelation and 2-D High-Frame-Rate Contrast-Enhanced Ultrasound. IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control (2018).
6. Flow Velocity Mapping Using Contrast Enhanced High-Frame-Rate Plane Wave Ultrasound and Image Tracking: Methods and Initial in Vitro and in Vivo Evaluation. Ultrasound in Medicine & Biology (2015).
7. A Deep Learning Approach to Resolve Aliasing Artifacts in Ultrasound Color Flow Imaging. IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control (2020).
8. Spatio-Temporal Flow and Wall Shear Stress Mapping Based on Incoherent Ensemble-Correlation of Ultrafast Contrast Enhanced Ultrasound Images. Ultrasound in Medicine & Biology (2017).
9. 4D ultrafast ultrasound flow imaging: in vivo quantification of arterial volumetric flow rate in a single heartbeat. Physics in Medicine and Biology (2016).
10. Measurement of turbulence statistics in single-phase and two-phase flows using ultrasound imaging velocimetry. Experiments in Fluids (2016).