Ultrasound Imaging Super-Resolution via Microbubble Differential Processing
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Solution Overview
Problem
Conventional ultrasound imaging methods are limited by a resolution of λ/2, where λ is the ultrasound wavelength, which is insufficient for precise imaging of scatterers in soft human tissue.
Innovation Solution
The method generates differential targets by comparing raw signals from successive measurement steps, extracting differential signals to determine the position of scatterers with high precision, allowing for image resolution better than λ/2, achieved through differential processing, adjustment, and positioning steps using an array of transducers and ultrasound contrast agents like microbubbles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional beamforming is used to combine raw signals from transducers, then the imaging process is simple and fast, but the image resolution is limited to λ/2
Solution Approach 1:
The patent segments the imaging process into distinct phases: generating differential targets (scatterers appearing/disappearing between successive measurements), extracting differential signals, adjusting functions to model wavefronts, and positioning scatterers. This segmentation allows super-resolution by focusing computational effort on detecting individual scatterer positions rather than processing entire images conventionally.
Solution Approach 2:
The patent performs preliminary actions by generating differential targets through controlled destruction of microbubbles or other scatterers between measurement steps. This preliminary creation of known scatterer states enables subsequent precise positioning by comparing signal differences, achieving resolution beyond the conventional λ/2 limit.
2Measurement precision
If multiple scatterers are activated simultaneously, then the imaging coverage is comprehensive, but the individual wavefront identification becomes difficult
Solution Approach 1:
The patent applies partial action by limiting the number of differential targets C to at most INT(A/(5λ)²)+1, where A is the field of observation area. This controlled limitation ensures that only a manageable number of scatterers are active simultaneously, allowing individual wavefront identification while maintaining sufficient imaging coverage through sequential measurements.
Solution Approach 2:
The patent uses periodic action by performing successive measurement steps with alternating scatterer states (present/absent). This periodic switching between measurement configurations enables the extraction of differential signals that reveal individual scatterer positions with high precision.
3Measurement precision
If the number of differential targets is limited to C=INT(A/(5λ)2)+1, then individual scatterers can be distinguished, but the maximum number of simultaneously detectable targets is constrained
Solution Approach 1:
The patent applies dynamics by allowing scatterers to be dynamically created and destroyed between measurement steps (e.g., through microbubble destruction). This dynamic control of scatterer presence enables the system to maintain a limited number of differential targets C while still achieving comprehensive imaging through multiple sequential measurements with different scatterer configurations.
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 approach enables precise positioning of scatterers to within λ/200, significantly improving ultrasound image resolution to λ/50 to λ/200, allowing for accurate identification and imaging of individual wavefronts with precision down to a few micrometers.
Implementation Method 1
an array of transducers emits an incident ultrasound wave into the field of observation... the incident waves mainly being propagated in a direction of propagation perpendicular to the array of transducers
Implementation Method 2
raw signals Sj(i,t) picked up by each transducer and representative of a reflected ultrasound wave reverberated from the incident wave by the scatterers in the environment
Implementation Method 3
a differential processing step during which the raw signals Sj(i,t) corresponding to successive measurement steps of index j are compared in order to extract differential signals Vj(i,t) representative of variations between raw signals from the successive measurement steps
Implementation Method 4
an adjustment step during which at least one function y=Pj(x) corresponding to each differential signal Vj(i,t) is determined, where x is a space variable denoting a position perpendicular to the direction of propagation and y is a coordinate denoting the position of a point along the direction of propagation
Implementation Method 5
a positioning step during which a crest Aj(x0,y0) of said function Pj, corresponding to the position of the differential target, is determined... it is possible to position them very accurately within the space with a precision much lower than λ/2, for example down to λ/200
Implementation Method 6
ultrasound contrast agents (microbubbles, microdroplets, or liposomes) are affected by ultrasounds which can cause them to burst or vaporize. This generates a target which appears and/or disappears in a very short time
Data Source
AI summary
A method of high-resolution ultrasound imaging, in which transducers are made to emit ultrasound waves in a field of observations containing micro bubbles, by making the micro bubbles burst one by one in tandem with the emissions of ultrasound waves. At each shot j of an ultrasound wave, raw reverberated signals Sj(i,t) picked up by each transducer i are recorded, and then differential signals Vj(i,t) representative of variations between successive raw signals are determined, a parabolic function Pj(x) is fitted to the differential signals corresponding to each shot j, and then a crest Aj(x0,y0) of this function Pj, corresponding to the position of the micro bubble destroyed between shots j−1 and j, is determined.