MRI Pilot Tone Signal Interference Removal
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Solution Overview
Problem
Magnetic Resonance Imaging (MRI) systems face challenges in removing radio frequency interference signals caused by transmission events during image acquisition, which degrade the quality of pilot tone signals and hinder the accurate measurement of physiological movements like breathing and heartbeat.
Innovation Solution
A signal processing method and device that synchronize the time series of control signals with the original reference radio frequency signal to identify and eliminate interference by setting sampling points and generating a fitting signal based on amplitude changes, using thresholds to determine fitting points and apply linear or nonlinear fitting algorithms as needed, to isolate and remove interference signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If radio frequency pulses are transmitted during image acquisition, then image data can be collected, but radio frequency interference signals are generated that degrade pilot tone signal quality
Solution Approach 1:
The patent segments the pilot tone signal into different time domains (before, during, and after radio frequency pulse transmission). By identifying and separating the interference-containing portion from the clean portions, the method can selectively process only the affected segments while preserving the useful signal information from non-interfered segments.
Solution Approach 2:
The patent extracts the radio frequency interference signal from the composite pilot tone signal by correlating with the known pulse sequence timing. Once extracted, the interference component is removed, leaving only the clean physiological movement information in the pilot tone signal.
2Measurement precision
If sampling points are selected near the transmission event, then interference can be modeled, but error probability increases due to signal instability
Solution Approach 1:
The patent performs preliminary identification of the echo train region by correlating the pilot tone signal with the pulse sequence timing information before attempting to model the interference. This preliminary step allows selection of sampling points that are temporally associated with the transmission event but positioned to minimize instability effects.
Solution Approach 2:
The patent dynamically adjusts the selection of sampling points based on the actual signal characteristics and interference patterns observed in each repetition time. Rather than using fixed sampling points, the method adapts the sampling positions to optimize the balance between capturing interference information and maintaining signal stability.
3Reliability
If fitting algorithms are applied to remove interference, then pilot tone signal quality improves, but computational complexity increases
Solution Approach 1:
The patent creates a model (copy) of the expected interference signal based on the known pulse sequence timing and characteristics. This template is then correlated with the actual pilot tone signal to identify and remove the interference components, avoiding the need for complex iterative fitting algorithms.
Solution Approach 2:
The patent replaces complex mechanical signal processing operations with mathematical correlation and subtraction operations. By using the known temporal structure of the pulse sequence, the interference removal is achieved through efficient mathematical operations rather than computationally intensive signal processing techniques.
Data Source
AI summary
A signal processing method including receiving an original reference radio frequency signal from a receiving antenna group; receiving the time series of the control signal associated with the transmission event of the radio frequency pulses; synchronizing the time series with the original reference radio frequency signal, and determining the echo train in the original reference radio frequency signal in a repetition time of the pulse sequence, wherein the echo train corresponds to the part of the time series associated with the transmission event of the radio frequency pulses in time sequence; setting the sampling points in the domains of the starting point and a first ending point of the echo train; and generating a fitting signal based on the sampling points to eliminate the radio frequency interference signal resulted from the transmission event of the radio frequency pulses.