Shear Wave Dispersion Vibrometry Tracking Pulse Sequences
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Solution Overview
Problem
Current Shear Wave Dispersion Vibrometry (SDUV) techniques face challenges in accurately measuring tissue shear elasticity and viscosity due to noise from system electronic noise and patient motion, and there is a risk of tissue heating from repeated acoustic exposure, which can lead to erroneous results and thermal safety concerns.
Innovation Solution
The method involves issuing tracking pulses to multiple locations after a single push pulse, sampling in separate passes or concurrently, and accounting for intersample delay to determine phase differences, which reduces noise and tissue heating by minimizing the number of push/tracking sequences, using a dual-purpose array transducer for both pushing and tracking, and implementing a novel spatiotemporal sampling scheme to estimate shear wave propagation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple push/tracking sequences are used to sample multiple locations, then measurement precision is improved, but tissue heating increases
Solution Approach 1:
The patent segments the sampling process into separate passes, where each pass samples a subset of locations. By dividing the locations into multiple groups and sampling them in sequential passes rather than simultaneously, the system reduces the cumulative acoustic exposure at any single location, thereby minimizing tissue heating while still achieving comprehensive coverage of all locations across multiple passes.
Solution Approach 2:
The patent implements periodic sampling by alternating between different sets of locations in successive passes. Instead of continuously sampling all locations, the system periodically switches between different location subsets, allowing thermal dissipation between sampling events at each location while maintaining measurement precision through the aggregated data from multiple passes.
2Productivity
If push pulses are issued frequently to establish shear waves, then data acquisition speed is improved, but tissue heating increases
Solution Approach 1:
The patent employs periodic action by issuing push pulses in a pulsed manner with sufficient intervals between them. Instead of continuous or overly frequent pulsing, the system uses periodic push pulses spaced appropriately to allow thermal dissipation, thereby maintaining data acquisition speed while preventing excessive tissue heating.
Solution Approach 2:
The patent applies preliminary action by issuing a single push pulse before the tracking sequences, establishing the shear wave field in advance. This preliminary push creates the shear wave that persists through multiple tracking passes, eliminating the need for repeated push pulses and thereby reducing thermal exposure while maintaining measurement capability.
3Device complexity
If a single-element transducer is used for tracking, then device complexity is reduced, but measurement precision deteriorates due to inability to sample multiple locations
Solution Approach 1:
The patent applies universality by designing the transducer system to perform multiple functions: the same single-element transducer alternates between pushing mode (generating shear waves) and tracking mode (sampling locations). This multi-functional approach eliminates the need for separate pushing and tracking transducers, reducing device complexity while maintaining measurement precision through the alternating operational modes.
Solution Approach 2:
The patent implements dynamics by making the transducer's function time-varying. The transducer dynamically switches between pushing and tracking roles across different time intervals and passes. This dynamic functional assignment allows a single transducer to effectively perform the work of multiple specialized transducers, reducing hardware complexity while preserving measurement accuracy through temporal separation of functions.
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 provides more robust and accurate measurements of tissue elasticity and viscosity while minimizing tissue heating and noise, enabling faster data acquisition and reducing the risk of thermal damage, thus advancing SDUV from a single-point tool to a real-time imaging modality.
Implementation Method 1
An ultrasound shear (or transverse) wave, by contrast, is characterized by back and forth in-place movement that is perpendicular to the direction of propagation. Oscillation one way creates the peaks, and the other way creates the valleys.
Implementation Method 2
Interrogation by ultrasound, for purposes of medical imaging, often makes use of longitudinal waves. In body tissue, the ultrasound propagates in wave form.
Data Source
AI summary
Shear Wave Dispersion Vibrometry (SDUV) is performed such that, after a single instance of their push pulse (218), a plurality of tracking pulses (222) are issued to sample, more than once, each of a plurality of locations (120, 148) on an associated monochromatic shear wave (116) in sampling that at least one of scans the plural locations in separate passes and, with a pulse of the plural tracking pulses, samples multiple ones of the plural locations concurrently. In a supplementary aspect, phase difference, for a given moment, is determined by taking into account intersample delay (156), if the determination relies on samples that are taken at different times.