Ultrasonic Doppler Flow Direction Detection
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Solution Overview
Problem
Current ultrasonic Doppler techniques, such as Multigate and Color Flow Mapping, fail to assess blood flow direction when the axis of the ultrasonic pulse beam is perpendicular to the blood flow, which is a common condition in diagnostic imaging, especially for venous blood flow in cerebral vessels, leading to inaccurate or undetectable flow direction due to symmetric Doppler frequency distributions.
Innovation Solution
A method that generates Doppler mean frequency signals and displays them in a graph with enhanced pixel appearance to differentiate flow direction, using a phased array probe with a sub-array of transducers to steer the ultrasound beam and receive signals, allowing for the detection of blood flow direction even when the beam is nearly perpendicular to the flow, by filtering low-frequency components and adjusting the frequency scale to enhance directionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ultrasonic Doppler techniques (Multigate or Color Flow Mapping) are used, then the detection of blood flow velocity is achieved, but the determination of blood flow direction fails when the ultrasonic beam axis is perpendicular to the blood flow direction
Solution Approach 1:
The patent applies asymmetry by introducing a small angular deviation from the perpendicular orientation between the ultrasonic beam and blood flow. This creates an asymmetric Doppler frequency distribution that breaks the symmetry of the perpendicular condition, enabling direction determination through comparison of Doppler shifts at different gates. The asymmetric arrangement allows the system to detect the slight frequency differences that indicate flow direction.
Solution Approach 2:
The patent transitions from a one-dimensional perpendicular measurement to a two-dimensional angular measurement by introducing multiple gates at different angular positions relative to the blood flow. This dimensional change allows the system to capture Doppler frequency variations across different angles, providing sufficient information to determine flow direction even when the primary beam is perpendicular to the flow.
2Illumination intensity
If the ultrasonic beam is oriented perpendicular to blood flow for imaging, then the anatomical visualization is optimized, but the Doppler frequency distribution becomes symmetric and direction information is lost
Solution Approach 1:
The patent segments the Doppler measurement into multiple gates positioned at different angular locations relative to the blood flow direction. Each gate captures a portion of the Doppler frequency spectrum, and by comparing the Doppler shifts across these segmented measurements, the system can determine the overall flow direction while maintaining the perpendicular beam orientation for optimal anatomical imaging.
Solution Approach 2:
The patent introduces an intermediary angular deviation from the perfect perpendicular orientation. This small angular offset acts as a mediator that preserves the primary benefit of perpendicular imaging (anatomical visualization) while introducing just enough asymmetry to recover direction information through multi-gate Doppler analysis.
3Measurement precision
If multiple Doppler gates are used to determine flow direction, then the processing complexity increases, but the direction detection accuracy improves
Solution Approach 1:
The patent applies local quality by positioning Doppler gates at specific angular locations where they can most effectively capture direction information. Rather than uniformly distributing gates, the system places them at strategically selected angles that maximize the asymmetry in Doppler frequency distribution, thereby improving direction detection accuracy with minimal additional processing complexity.
Solution Approach 2:
The patent changes the angular parameter of the ultrasonic beam relative to the blood flow from exactly perpendicular to slightly off-perpendicular. This parameter change creates the necessary asymmetry in Doppler frequency distribution, enabling direction determination while keeping the processing complexity manageable through controlled angular deviation rather than complex multi-dimensional measurements.
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
This method effectively differentiates blood flow direction and velocity within vessels, providing clear indication of flow direction and velocity profiles, even in challenging imaging conditions, without increasing processing time or requiring additional data acquisition.
Implementation Method 1
transmitting ultrasound waves into the subject under study
Implementation Method 2
determining the velocity of a scatterer from the frequency or phase shift, which affects a back-scattered ultrasound beam according to the Doppler effect
Implementation Method 3
using a phased array probe with a sub-array of transducers to steer the ultrasound beam and receive signals
Data Source
AI summary
A method for ultrasonic detection and imaging of hemodynamic information includes the steps of transmitting ultrasonic pulses into a body, which are generated by an array of electro-acoustic transducers arranged in a predetermined order and design; receiving reflected pulses with an array of receiving electro-acoustic transducers, which generate receive signals upon stimulation of the reflected pulses, the succession of pulses transmitted to or received from the body being focused along one or more scan lines; generating a Doppler frequency shift signal resulting from the reflection of pulses transmitted by a blood flow into a vessel intersected by the scan line, in a point and along the scan line, or along a direction of propagation of a pulse; determining the direction of blood flow velocity from the average frequency value of Doppler shift frequencies; and displaying the direction of blood flow velocity by graphical and/or chromatic representation differentiating opposite directions.