Elastography Resting-Value Measurement for Liver Stiffness Variability
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Solution Overview
Problem
Existing elastography techniques for measuring liver or spleen stiffness, such as VCTE-based methods, suffer from variability due to factors like respiration, blood pressure, and probe inclination, leading to overestimations and reduced diagnostic accuracy.
Innovation Solution
An elastography method and device that acquires measurements at a high repetition rate to identify a 'resting value' by filtering out variations caused by respiration and probe alignment, using a threshold to select measurements for determining a corrected mechanical property value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional elastography measurement methods are used, then stiffness values can be obtained, but the measurements are influenced by respiration, blood pressure, and probe inclination causing overestimation and variability
Solution Approach 1:
The system performs preliminary actions by acquiring multiple measurements at a high repetition rate (at least 4 measurements per second) before determining the final stiffness value. This preliminary data collection allows the system to capture the natural variations caused by respiration and blood pressure, enabling subsequent selection of the most representative measurement.
Solution Approach 2:
The system changes the measurement parameter by introducing a temporal dimension - instead of taking a single stiffness measurement, it acquires multiple measurements over time and uses signal processing to identify the resting value. This parameter change from static to dynamic measurement allows differentiation between true stiffness and artifacts caused by physiological movements.
2Reliability
If multiple stiffness measurements are collected to improve reliability, then more data is available, but the variability in the series of measurements remains large due to physiological factors
Solution Approach 1:
The system extracts the relevant information by selecting only the measurements that represent the true stiffness value, excluding those influenced by respiration or blood pressure. This is achieved by processing the series of measurements to identify the 'resting value' - the measurement taken when the subject is in a neutral physiological state, effectively separating the true stiffness signal from physiological noise.
Solution Approach 2:
The system uses feedback by continuously monitoring the series of stiffness measurements and using this information to guide the selection process. The processing circuit analyzes the temporal pattern of measurements to identify which ones represent the resting state, creating a feedback loop that improves measurement accuracy by learning from the observed variations.
3Ease of operation
If the probe is not held perfectly perpendicular to the body surface, then ease of operation improves, but measurement accuracy deteriorates due to overestimation from probe inclination
Solution Approach 1:
The system performs self-correction by using the series of measurements to identify and compensate for probe inclination effects. Instead of relying on the operator to maintain perfect perpendicularity, the system automatically processes the measurements to extract the true stiffness value, making the measurement process self-correcting and reducing dependence on operator skill.
Solution Approach 2:
The system applies partial action by selecting only the measurements that are not affected by probe inclination from the series of acquired measurements. By acquiring more measurements than necessary and then selecting only the valid ones, the system ensures that the final result is not compromised by occasional improper probe positioning.
4Measurement precision
If the subject holds their breath to eliminate respiration effects, then measurement accuracy improves, but the procedure becomes more complicated and difficult for overweight subjects
Solution Approach 1:
The system converts the harmful effect of respiration into a beneficial one by using the natural respiratory cycle to create distinct measurement phases. Instead of trying to eliminate respiration, the system acquires measurements throughout the respiratory cycle and identifies the resting value from measurements taken during normal breathing, effectively using respiratory motion as a temporal marker rather than a source of error.
Data Source
AI summary
An elastography method includes acquiring, at a repetition rate of at least 4 measurements per second and for a duration of at least 3 seconds, measurements of a mechanical property of a region of a body of a subject, the region being a part of a liver or a part of a spleen of the subject; obtaining a signal representative of the variations of the mechanical property with time, the signal including at least part of the measurements of the mechanical property determined; in each portion of the signal among at least one portion of the signal, select measurements, among the measurements included in the portion of the signal, lower than or equal to a threshold associated with the portion of the signal; and determining a value representative of the mechanical property, called resting value, based on the selected measurements.