Elastography Measurement of Liver Stiffness Over the Cardiac Cycle
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Solution Overview
Problem
Conventional elastography techniques for liver stiffness measurement (LSM) suffer from significant variability due to factors like probe positioning, respiratory cycles, and cardiac influences, leading to inaccurate and inconsistent results, as they typically acquire measurements at intervals greater than 1 second, neglecting the dynamic variations of liver stiffness over time.
Innovation Solution
An elastography device and method that acquire measurements at a high repetition rate (at least 4 measurements per second) for a duration of at least 1 second, capturing variations in liver stiffness over a cardiac cycle, using a VCTE device with a low-frequency mechanical pulse and ultrasound transducer to track elastic wave propagation, and process these measurements using a specialized processor to generate a signal representative of mechanical property variations over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measurements are acquired at conventional intervals (greater than 1 second), then the measurement process is simple and quick, but the measurement precision deteriorates due to significant variability from respiratory cycles and cardiac influences
Solution Approach 1:
The system performs preliminary acquisition of multiple measurements (at least 10 measurements) at high repetition rate (at least 4 measurements per second) before processing. This preliminary action captures the dynamic variations of liver stiffness over time, including cardiac cycle influences, allowing subsequent selection of optimal measurements that represent true liver stiffness while filtering out transient variations from respiration and cardiac motion.
Solution Approach 2:
The system transitions from static, single-timepoint measurements to dynamic, time-resolved measurements. By acquiring measurements at least 4 times per second for at least 1 second, the system captures the temporal dynamics of liver stiffness variations, enabling differentiation between true stiffness changes and transient variations caused by respiratory and cardiac cycles.
2Reliability
If multiple measurements are acquired to account for variability, then the reliability of the final measurement improves, but the complexity of the device and measurement process increases
Solution Approach 1:
The system replaces complex mechanical adjustment mechanisms with an electronic solution. Instead of requiring precise manual control of measurement timing and positioning, the system uses electronic timing control to automatically acquire multiple measurements at high repetition rate, with the electronic unit selecting optimal measurements based on predefined criteria. This substitution of electronic control for mechanical complexity maintains reliability while simplifying operation.
Solution Approach 2:
The system changes the temporal parameter of measurement acquisition by implementing a high repetition rate (at least 4 measurements per second) and extended duration (at least 1 second). This parameter change allows capture of multiple cardiac and respiratory cycles, enabling statistical selection of representative measurements that improve reliability without requiring complex additional hardware.
3Measurement precision
If measurements are taken over a longer duration to capture cardiac cycle variations, then the measurement precision improves, but the productivity of the diagnostic process decreases
Solution Approach 1:
The system performs excessive action by acquiring at least 10 measurements at high repetition rate (at least 4 measurements per second) for at least 1 second, which exceeds the minimum needed to capture cardiac cycle variations. This excessive action ensures capture of multiple complete cardiac and respiratory cycles, allowing selective extraction of the most representative measurements. The additional measurements provide redundancy that improves precision while the automated selection process maintains diagnostic throughput.
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
The high-repetition-rate approach allows for precise determination of liver stiffness variations, providing more accurate indicators and features, such as median values that reflect the true mechanical behavior of the liver, and enables detection of cardiac cycle influences on liver stiffness, reducing noise and improving diagnostic precision.
Implementation Method 1
An ultrasound transducer mounted on the probe's tip, in contact with the subject's body, then emits a number of ultrasound shots into the tissue
Implementation Method 2
The echo signals, corresponding to the backscattering of the different ultrasound shots emitted, are acquired by the probe
Implementation Method 3
This pulse generates elastic waves that travel in the subject's body
Implementation Method 4
The mechanical pulse delivered by the probe's tip generates both a shear wave and of a compression wave
Implementation Method 5
The mechanical pulse delivered by the probe's tip generates both a shear wave and of a compression wave
Data Source
AI summary
An elastography device to obtain a signal representative of variations of a mechanical property of a region of a body of a subject with time, includes an electronic unit adapted to determine, at a repetition rate of at least 4 measurements per second and for a duration of at least 1 second, measurements of the mechanical property, each measurement being associated with a respective time, wherein the signal representative of the variations of the mechanical property with time includes a plurality of the measurements of the mechanical property determined.