Plane Wave Compounding With Initial Phase Compensation in Ultrasound
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Solution Overview
Problem
Plane wave compounding in ultrasound imaging suffers from phase shift errors, particularly when the absolute value of the initial phase difference between two transmissions exceeds π/2, leading to inaccurate motion estimation and reduced signal-to-noise ratio (SNR).
Innovation Solution
The Initial-Phase-Compensated Plane Wave Compounding (IPCPWC) method compensates the initial phase of echo signals from each plane wave transmission to maintain the absolute value of the initial phase difference (IPD) below π/2, ensuring accurate phase shift estimation and improved SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple angled plane wave transmissions are used for plane wave compounding to improve signal-to-noise ratio, then image quality is improved, but the number of transmissions increases to more than 70 angles and acquisition time increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal weighting factors for different transmission angles before the actual imaging process. This allows the system to rapidly combine signals from multiple angles using pre-determined weights, significantly reducing the time required for signal compounding while maintaining high signal-to-noise ratio.
Solution Approach 2:
The patent changes the parameter of transmission angle selection by using a reduced set of specific angles with optimized weighting factors rather than uniformly sampling many angles. This parameter optimization achieves effective signal compounding with fewer transmissions, reducing acquisition time while preserving image quality.
2Reliability
If adaptive beamforming techniques are used to improve B-mode image quality with fewer transmissions, then image quality is improved, but phase shift estimation accuracy for motion measurement deteriorates
Solution Approach 1:
The patent segments the imaging process into two distinct modes: B-mode imaging using adaptive beamforming for high image quality, and motion estimation using conventional delay-and-sum beamforming for accurate phase shift measurement. This segmentation allows each mode to use the most appropriate technique without compromising the other.
Solution Approach 2:
The patent implements dynamic switching between different beamforming strategies based on the current operational requirement. When B-mode imaging is needed, adaptive beamforming is applied; when motion estimation is required, the system switches to conventional beamforming to preserve phase shift estimation accuracy.
3Productivity
If plane wave compounding with fewer angles is used for ultrafast acquisitions, then frame rate is maintained, but axial lobe and side lobe artifacts increase
Solution Approach 1:
The patent applies asymmetry by using non-uniform weighting factors assigned to different transmission angles in the compounding process. Instead of equal weighting, specific angles receive higher weights based on their contribution to reducing artifacts, thereby suppressing axial lobe and side lobe artifacts while maintaining high frame rate with fewer transmissions.
4Reliability
If phase encoding or frequency encoding methods are used in coded excitation plane wave imaging to improve sensitivity to shear wave motion, then signal-to-noise ratio is improved, but system complexity increases
Solution Approach 1:
The patent employs simpler, computationally efficient encoding schemes that can be rapidly implemented and discarded between measurements, rather than using complex persistent encoding structures. This approach achieves high sensitivity to shear wave motion through straightforward signal processing that minimizes system complexity.
Data Source
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AI summary
Systems and methods for Plane Wave Compounding ("PWC") are provided for improving image quality with reduced phase shift errors. The initial phase difference ("IPD") between two PW transmissions is related to the phase shift error. When the absolute value of IPD is larger than π/2, the phase shift error occurs. An Initial-Phase-Compensated PWC ("IPCPWC") method may be used to compensate the initial phase of echo signals from each PW transmit and maintain the absolute value of IPD smaller than π/2, IPCPWC methods may also include increased motion signal-to-noise ratio and reduced jitter.