Nonlinear Frequency Compounding for Ultrasound Clutter Reduction
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Solution Overview
Problem
B-mode imaging in ultrasound technology faces challenges with image clarity and depth penetration due to the traditional dismissal of the Direct Current (DC) harmonic signal, which carries valuable information for enhancing image penetration and clutter reduction.
Innovation Solution
A method and system that simultaneously generates and utilizes the DC harmonic, fundamental, and second harmonic signals using standard pulse inversion transmission, allowing for selective compounding and weighted image generation to optimize image quality based on depth and clinical needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the DC harmonic signal is removed from the imaging process to eliminate low frequency noise, then image clutter is reduced, but image penetration and diagnostic information are worsened
Solution Approach 1:
The patent segments the harmonic signal into distinct frequency components: the DC component (0 Hz), second harmonic signals (2f), and fourth harmonic signals (4f). By separating these components through spectral analysis, the system can selectively process and combine them to reduce clutter while preserving penetration information. This segmentation allows the DC component to be handled differently from traditional approaches, converting it from harmful noise to a useful signal source.
Solution Approach 2:
The patent converts the previously harmful DC component (traditionally dismissed as low frequency noise) into a beneficial signal source for image penetration. By applying spectral analysis and selective compounding, the system transforms the DC harmonic signals that were once considered clutter into valuable information carrying deep tissue penetration capabilities, thereby converting a harmful factor into a benefit.
2Measurement precision
If multiple signal types (DC, fundamental, 2nd harmonic) are extracted and compounded to improve image quality, then image penetration and clarity are enhanced, but system complexity increases
Solution Approach 1:
The patent employs a unified signal processing framework that handles multiple signal types (DC component, fundamental, second harmonic, fourth harmonic) through a single spectral analysis and compounding process. The same signal extraction and compounding infrastructure processes all harmonic components, making the system multi-functional without proportionally increasing complexity. This universal approach allows flexible combination of different signal types for various imaging needs.
Solution Approach 2:
The patent utilizes parameter changes in the frequency domain through spectral analysis to separate and process different harmonic components. By transforming the time-domain signal into the frequency domain and manipulating spectral parameters, the system can selectively extract and compound specific frequency components (DC, 2f, 4f) with controlled weighting, achieving enhanced image clarity through systematic parameter management rather than complex hardware modifications.
3Measurement precision
If traditional pulse inversion transmission is used to generate harmonic signals, then second harmonic signals are obtained for improved imaging, but the DC component is lost and treated as noise
Solution Approach 1:
The patent transitions from time-domain signal processing to the frequency domain through spectral analysis. This dimensional change from time to frequency representation reveals the DC component (0 Hz) and other harmonic components that were previously mixed together. By operating in the frequency domain, the system can selectively identify and extract the DC component alongside second and fourth harmonic signals, preventing information loss that occurs in traditional time-domain pulse inversion methods.
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
Enhances image penetration, clarity, and reduces clutter without sacrificing frame rate, improving diagnostic capabilities in challenging imaging scenarios like trans-cranial and fetal skull imaging.
Implementation Method 1
As acoustic waves travel through nonlinear tissues, they generate a spectrum of signals, including very low frequency signals centered at DC (0 Hz) and nonlinear 2nd harmonic signals.
Implementation Method 2
B-mode imaging... generates two-dimensional cross-sectional images by interpreting the reflection (echo) intensity of ultrasound waves as they propagate through various tissues within the body.
Implementation Method 3
a novel system and method are described that capitalize on the regular pulse inversion transmission technique to not only generate the DC signal and the 2nd harmonic signal but also the fundamental signal (and potentially other odd-order harmonic signals), simultaneously
Data Source
AI summary
An ultrasound imaging system is disclosed that performs enhanced B-mode imaging through a pulse inversion (PI) process. A controller transmits a PI sequence including a positive and a negative ultrasound pulse into biological tissue. A signal processing circuit receives echo signals resulting from this PI sequence and extracts three distinct signals: a direct current harmonic (DCH) signal, a fundamental signal at the transmitted frequency, and a second harmonic signal. Weights are assigned to these signals to create weighted signals spanning different nonlinear frequency bands. A final image is then generated from these weighted signals, improving image penetration, resolution, and clutter reduction compared to standard methods.