Curved Virtual Transducer Arrays for Angle-Independent Vector Flow
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Solution Overview
Problem
Existing ultrasound techniques for flow estimation, such as color-flow imaging and pulsed-wave Doppler, provide one-dimensional views and are angle-dependent, leading to inaccuracies in tortuous vasculature and polar field of views, particularly in deep vascular imaging like portal vein imaging.
Innovation Solution
A method and apparatus using a virtual transducer array that emits Archimedean spiral waves, allowing for the estimation of both axial and lateral velocity components by processing Doppler signals from these waves, leveraging their directivity in polar coordinates to overcome angle dependency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard ultrasound techniques (color-flow imaging, pulsed-wave Doppler) are used, then one-dimensional flow measurements are obtained, but angle dependency causes inaccuracies in tortuous vasculature and deep vascular imaging
Solution Approach 1:
The patent transitions from one-dimensional Doppler measurements to two-dimensional vector flow imaging by using multiple plane wave transmissions at different angles. This dimensional expansion allows simultaneous measurement of both axial and lateral velocity components, eliminating angle dependency and enabling accurate flow visualization in tortuous and deep vascular structures
Solution Approach 2:
The system uses a single ultrasound probe to perform multiple functions: transmitting plane waves at various angles, receiving scattered signals, and computing both axial and lateral velocity components. This multi-functional approach replaces the need for multiple specialized techniques while providing comprehensive flow information across different vascular geometries
2Measurement precision
If multi-beam Doppler methods are used for vector flow imaging, then axial and lateral velocity components are obtained, but aliasing potential increases in deep vascular imaging
Solution Approach 1:
The patent changes the transmission parameter by using plane waves instead of focused beams, and employs ultrafast imaging to achieve very high frame rates. This parameter change increases the pulse repetition frequency, thereby expanding the Doppler velocity range and reducing aliasing in deep vascular imaging while maintaining accurate velocity component measurement
3Length of stationary object
If conventional ultrasound arrays are used, then standard imaging is achieved, but deep vascular imaging with curvilinear arrays lacks suitable vector flow imaging capability
Solution Approach 1:
The patent segments the curvilinear array into multiple virtual linear sub-arrays, each capable of transmitting plane waves independently. This segmentation allows application of plane wave imaging techniques to curvilinear arrays, enabling accurate vector flow estimation in deep vascular structures while maintaining the depth penetration advantages of curvilinear geometry
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate estimation of both axial and lateral velocity components, suitable for deep vascular imaging, reducing aliasing and improving accuracy in complex flow visualization.
Implementation Method 1
By using a number of pulse emissions, the inter pulse movement can be estimated and the velocity found from the estimated movement and the time between pulses
Implementation Method 2
The movement of the scatterer is determined by emitting and receiving a pulsed wave field with an array of transducers
Data Source
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AI summary
The invention concerns an apparatus for estimating a velocity of at least one scatterer in a medium, the apparatus comprising a generator for generating excitation signals, a curved array of virtual transducers (T1-Tn) for transforming said excitation signals into Archimedean spiral waves and for: • emitting said Archimedean spiral waves in a plurality of predetermined directions of propagation defined by a set of insonifi cation angles (αi), a curvature of said curved array of virtual transducers defining a reference center (O) and a radius of curvature (rn), • and for receiving, from said at least one scatterer, scattered signals generated by scattering of said Archimedean spiral waves emitted from said curved array of virtual transducers, a driving and processing unit (Uc) for estimating the velocity of said at least one scatterer wherein axial and lateral velocity components are estimated using a set of local wavefront orientations (aeq,i) of the Archimedean spiral waves as a function of the initial set of insonification angles (αi), the geometry of the curved array of transducers and the distance (r) to the reference center (O), each local wavefront orientation satisfying the following formula:.