Phase-to-amplitude slope mapping for respiratory motion artifacts
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Solution Overview
Problem
Respiratory phase-based imaging techniques face challenges due to irregular breathing cycles, where expiration rates differ from inspiration rates, cycle shapes vary, and lung mechanical states during inhalation do not match exhalation, leading to misalignment and motion artifacts in reconstructed images.
Innovation Solution
A method and system that utilize phase-to-amplitude/slope mapping to identify and align motion phases in cyclic signals, correlating timestamps based on both amplitude and slope to select consistent projection data for reconstruction, thereby mitigating misalignment and motion artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If linear phase division is used based on signal maxima and minima, then the breathing cycle is divided into phases, but the phases do not linearly span across a cycle due to different expiration and inspiration rates
Solution Approach 1:
The patent changes the parameter basis for phase mapping from simple linear time division to a combination of amplitude and slope parameters. By using amplitude (signal strength) and slope (rate of change) to define phases, the system accounts for the non-linear nature of respiratory cycles where inspiration and expiration rates differ, achieving more accurate phase alignment across varying breath patterns.
2Productivity
If timestamps are identified based on percentage of cycle, then projection data can be selected for reconstruction, but anatomical structures may not align due to varying breathing cycle shapes
Solution Approach 1:
The patent transitions from using cycle percentage alone to using a composite of amplitude and slope parameters for timestamp identification. This allows the system to select projection data that corresponds to consistent anatomical states across different breath cycles, even when cycle durations and shapes vary, thereby improving anatomical alignment in reconstructed images.
Solution Approach 2:
The system uses the respiratory signal itself as feedback to dynamically adjust phase mapping. By continuously monitoring amplitude and slope parameters from the respiratory waveform, the system adapts to varying breathing patterns in real-time, ensuring that timestamps correspond to consistent anatomical positions regardless of cycle-to-cycle variations.
3Ease of operation
If phase-based gating is used with linear division, then individual breathing cycles are identified, but motion artifacts are introduced due to mismatched mechanical states
Solution Approach 1:
The patent employs amplitude and slope parameters instead of simple linear phase division to identify corresponding points in the respiratory cycle. By mapping phases based on these physical parameters, the system ensures that projection data selected for reconstruction represents consistent mechanical states of the lungs, thereby reducing motion artifacts while maintaining the breath-freezing capability.
Data Source
AI summary
A method includes obtaining a signal that includes a plurality of cycles and generating a map that maps motion phases to the signal based on both an amplitude and a slope of the signal. A system includes a processor that identifies a set of motion signal timestamps, for a plurality of motion cycles in a motion signal indicative of cyclic motion of a moving object, based on a predetermined motion phase of interest and a phase-to-amplitude/slope mapping, wherein the set of motion signal timestamps correspond to a common signal amplitude. A method include identifying a peak of a plurality of peaks in a motion cycle of a noisy cyclic signal having irregular periodicity, wherein the peak corresponds to a point lying between two points with amplitudes below a predetermined threshold, comparing points before and after the peak with the peak, and identifying the peak as a local maximum when the peak is greater than the points.