Ultrasonic Reflection Matrix Imaging for Aberration Correction
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Solution Overview
Problem
Conventional ultrasound imaging methods are limited by aberrations caused by variations in the speed of sound in heterogeneous media, leading to degraded resolution and contrast in ultrasound images, particularly in medical imaging where the assumption of a homogeneous medium is often violated.
Innovation Solution
A method for ultrasonic characterization involving the generation of incident waves, construction of an experimental reflection matrix, and determination of a focused reflection matrix with an additional delay, followed by a frequency matrix analysis to characterize the medium locally and improve image resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional ultrasound imaging methods are used with a homogeneous medium assumption, then the imaging process is simple and fast, but the resolution and contrast are degraded due to speed of sound variations in heterogeneous media
Solution Approach 1:
The patent changes the parameter of speed of sound from a constant homogeneous value to a spatially varying heterogeneous field. By measuring and incorporating local speed of sound variations at different positions in the medium, the system corrects phase shifts and improves image resolution without sacrificing imaging speed, as the corrections are applied through signal processing of the reflected wave patterns.
Solution Approach 2:
The patent implements a feedback mechanism where the reflected ultrasonic waves are analyzed to determine local speed of sound characteristics, which then feed back into the imaging process to correct aberrations. The system uses the measured speed of sound variations to adjust the focusing and timing of subsequent emissions, creating a closed-loop system that continuously optimizes image quality.
2Measurement precision
If focused emissions are used to improve resolution, then image quality improves, but the acquisition time increases significantly
Solution Approach 1:
The patent performs preliminary measurement of the speed of sound field before conducting focused emissions for imaging. By characterizing the medium's acoustic properties in advance, the system can pre-calculate correction factors and focusing parameters, allowing subsequent high-resolution imaging to be performed more efficiently without repeated medium characterization.
Solution Approach 2:
The patent applies local quality by determining speed of sound variations at specific positions within the medium and applying targeted corrections only where needed. Rather than uniformly focusing energy throughout the entire medium, the system identifies and corrects local aberrations, reducing the overall acquisition time while maintaining high resolution in critical regions.
3Device complexity
If the medium is characterized as homogeneous with constant speed of sound, then the imaging process is simplified, but aberrations occur leading to distorted wavefronts and degraded image quality
Solution Approach 1:
The patent enables the imaging system to self-characterize the medium by analyzing the reflected ultrasonic waves from natural scatterers within the medium itself. The system uses the medium's own scattering properties to measure speed of sound variations and automatically correct for them, eliminating the need for external calibration or complex manual characterization procedures.
Solution Approach 2:
The patent uses reflected ultrasonic waves as an intermediary to probe and characterize the medium's speed of sound distribution. These reflected waves carry information about the medium's acoustic properties, which are then decoded to create a speed of sound map that serves as a mediator for correcting subsequent imaging emissions.
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 precise, local assessment of focusing quality and improved ultrasound image resolution by identifying and characterizing scatterers in real-time, overcoming aberrations and enhancing image clarity.
Implementation Method 1
conventional ultrasound methods use an array 10 of piezoelectric transducers 11 which can emit and/or receive ultrasonic pulses independently
Implementation Method 2
This wave is reflected by the scatterers 21 of the medium 20 and the backscattered field is recorded as a function of time by each of the transducers 11
Implementation Method 3
the responses of the output virtual transducer TVout being obtained at a time instant that is shifted by an additional delay δt relative to a time instant of the responses of the input virtual transducer TVin
Implementation Method 4
a step of determining a frequency matrix RFreqt(r, ω) which is a temporal Fourier transform of each cell of the focused reflection matrix RFoc(r, δt)
Data Source
AI summary
Method for ultrasonic characterization of a medium, comprising a step of generating a series of incident ultrasonic waves, a step of generating an experimental reflection matrix Rui(t) defined between the emission basis (i) as input and a reception basis (u) as output, a step of determining a focused reflection matrix RFoc(rin, rout, δt) of the medium between an input virtual transducer (TVin) calculated based on a focusing as input to the experimental reflection matrix and an output virtual transducer (TVout) calculated based on a focusing as output from the experimental reflection matrix, the responses of the output virtual transducer (TVout) being obtained at a time instant that is shifted by an additional delay δt relative to a time instant of the responses of the input virtual transducer (TVin).