Respiratory-Gated Elastography for Consistent Liver Stiffness Measurement
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Solution Overview
Problem
Existing elastography techniques for measuring liver or spleen stiffness, such as VCTE-based methods, suffer from significant variability in measurements due to factors like central venous pressure and hemodynamics, which are not adequately accounted for, leading to inconsistent results.
Innovation Solution
An elastography method that synchronizes the acquisition of mechanical property measurements with specific moments of the subject's respiratory cycle, such as the end of inspiration or expiration, to reduce variability and improve measurement precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple stiffness measurements are collected at different timepoints, then a representative stiffness value can be derived, but measurement variability remains large due to respiratory and hemodynamic factors
Solution Approach 1:
The patent applies periodic action by synchronizing stiffness measurements to specific phases of the respiratory cycle (e.g., end-expiration or end-inspiration). Instead of taking measurements at random or arbitrary timepoints, the system waits for the respiratory signal to reach a predetermined phase before acquiring each measurement. This periodic synchronization ensures that all measurements are taken under comparable physiological conditions, thereby reducing variability and improving both precision and reliability of stiffness measurements
Solution Approach 2:
The patent implements feedback by continuously monitoring the respiratory signal and using it to trigger or gate the acquisition of stiffness measurements. The system measures respiratory phase in real-time and provides feedback control to the measurement acquisition timing. This closed-loop approach ensures that measurements are automatically synchronized to the correct respiratory phase without manual intervention, eliminating operator-dependent variability and improving measurement consistency
2Reliability
If 10 stiffness measurements are obtained to ensure reliable results, then diagnostic accuracy improves, but measurement time and patient discomfort increase
Solution Approach 1:
By synchronizing measurements to periodic respiratory phases, the patent enables more efficient data collection. Instead of requiring 10 measurements taken at arbitrary intervals, the system can acquire multiple measurements during a single respiratory cycle by targeting specific phases (e.g., both end-expiration and end-inspiration). This approach maintains diagnostic reliability while reducing the total time required, as measurements are concentrated during naturally occurring physiological windows rather than being spread out over extended periods
Solution Approach 2:
The patent applies preliminary action by pre-defining the optimal respiratory phases for measurement acquisition before the actual stiffness measurement process begins. The system identifies and marks the target phases (such as end-expiration) in advance based on respiratory signal analysis, then systematically acquires measurements at these predetermined points. This planning approach allows for efficient scheduling of multiple measurements within a compressed time window, reducing overall examination time while maintaining the required number of measurements for diagnostic reliability
3Ease of operation
If measurements are taken during normal breathing, then patient comfort is maintained, but hemodynamic effects introduce variability in stiffness values
Solution Approach 1:
The patent resolves this contradiction by utilizing the periodic nature of respiration to its advantage. Instead of trying to eliminate respiratory effects, the system synchronizes measurements to specific phases (such as end-expiration when intrathoracic pressure is most stable). This approach maintains normal breathing throughout the procedure, preserving patient comfort, while the phase-specific timing compensates for hemodynamic variability by consistently measuring at the most stable point in the respiratory-hemodynamic cycle
Data Source
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AI summary
An aspect of the invention relates to an elastography method implemented by an elastography device, the method comprising: - obtaining a respiratory signal related to a respiratory activity of a subject; and - acquiring a plurality of measurements of a mechanical property of a region of a body of the subject, the region being a part of a liver or a spleen of the subject; wherein each measurement among at least a subset of the plurality of measurements of the mechanical property is acquired at a same moment of a respective respiratory cycle determined from the respiratory signal.