Ultrasonic Imaging Spatial Compounding via Virtual Apex Beam Steering
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Solution Overview
Problem
Conventional ultrasonic diagnostic imaging systems face challenges in achieving uniform spatial compounding throughout the image field due to varying degrees of image overlap in different areas, limiting the effectiveness of spatial compounding in trapezoidal sector formats.
Innovation Solution
The implementation of virtual apex phased beam steering, where scanlines are steered at different angles relative to the transducer face, allowing for the acquisition of component frames that overlap substantially across the image field, thereby enhancing spatial compounding throughout a large region of the compounded image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ultrasonic diagnostic imaging systems use standard sector scanning, then the image acquisition is simple, but the spatial compounding effect is non-uniform throughout the image field
Solution Approach 1:
The imaging field is divided into multiple trapezoidal sub-regions, each scanned by a dedicated component frame with specific steering angles. This segmentation allows uniform spatial compounding across the entire image field by ensuring each region receives appropriate angular diversity without requiring complex dynamic adjustments.
Solution Approach 2:
The system pre-calculates and pre-positions multiple component frames at specific steering angles before image acquisition. By preparing the angular configurations in advance, the system achieves uniform spatial compounding without requiring complex real-time adjustments during scanning.
2Adaptability or versatility
If the transducer array element pitch is reduced to increase angular diversity, then more specular interfaces become visible, but the acceptance angle is limited by the pitch
Solution Approach 1:
Instead of reducing element pitch in the lateral dimension, the system introduces angular diversity by steering beams in different directions (adding an angular dimension). Multiple component frames are acquired at different steering angles, providing angular diversity without changing the physical transducer geometry.
Solution Approach 2:
The system creates multiple virtual copies of the transducer array, each oriented at different steering angles. These virtual arrays are synthesized through electronic beam steering, allowing the system to access multiple angular perspectives without physically modifying the transducer element pitch.
3Reliability
If spatial compounding is performed with varying image overlap in different areas, then the processing is simpler, but the speckle reduction and interface visibility are non-uniform
Solution Approach 1:
The system applies different processing weights to different regions of the compounded image based on the number of overlapping component frames. Regions with higher overlap (better speckle reduction) receive appropriate weighting, while regions with lower overlap are compensated through adaptive processing, ensuring uniform image quality across the entire field.
Solution Approach 2:
The system dynamically adjusts processing parameters such as compounding weights and normalization factors based on the local overlap characteristics of each image region. This parameter adaptation ensures consistent speckle reduction and interface visibility throughout the image field while maintaining processing efficiency through region-based optimization.
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 results in a high degree of spatial compounding across a large region of the image, improving image quality by reducing speckle and enhancing the visibility of specular interfaces, with the region of maximum image quality extending virtually across the entire image field.
Implementation Method 1
An ultrasound probe including a planar array transducer which transmits beams at different angles over an image field
Implementation Method 2
A digital beamformer delays and sums the echoes from the array elements or microbeamformer to form a sequence of focused, coherent digital echo samples along each scanline
Implementation Method 3
The component frames are combined into a compound image by summation, averaging, peak detection, or other combinational means. The compounded image typically shows lower speckle and better specular reflector delineation than conventional ultrasound images from a single viewpoint
Data Source
AI summary
An ultrasonic diagnostic imaging system produces spatially compounded trapezoidal sector images by combining component frames acquired from different look directions. A virtual apex scan format is used such that each scanline of a component frame emanates from a different point on the face of an array transducer and is steered at a different scanning angle. For different component frames the scanlines are steered at respectively different angles. In an illustrated example, the scanlines of each component frame are incremented by five degrees relative to the corresponding scanlines in a reference component frame. When the component frames are combined for spatial compounding, the maximum number of component frames are combined over virtually the entire image field.