MRI Wireless RF Coil Timing Offset Correction
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Solution Overview
Problem
In magnetic resonance imaging (MRI) systems, wireless RF coils face challenges with synchronization between transmit (Tx) and receive (Rx) clocks, leading to image quality deterioration due to phase rotation and frequency mismatch, which existing solutions fail to adequately address, especially in wireless setups where phase errors accumulate and system noise affects accuracy.
Innovation Solution
The implementation of a method using navigator echoes to acquire additional data for retrospective correction of timing offsets between Tx and Rx clocks, allowing for phase and frequency mismatch adjustments in the raw data without requiring hardware changes, utilizing a bi-directional wireless link and amplitude modulation techniques to synchronize clocks with microsecond-level accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless RF coils are used to eliminate cables, then ease of operation and flexibility are improved, but timing synchronization between transmit and receive clocks deteriorates, causing phase rotation and frequency mismatch
Solution Approach 1:
The system performs preliminary actions by acquiring navigator echoes before the main imaging sequence to detect and characterize timing offsets between transmit and receive clocks. These preliminary measurements enable retrospective correction of the timing synchronization issues in the actual imaging data, allowing wireless operation without sacrificing measurement precision.
Solution Approach 2:
The system implements feedback by using navigator echoes to continuously monitor timing offsets between transmit and receive clocks. The detected phase and frequency information is fed back to correct the timing synchronization errors in the main imaging data, enabling wireless RF coils to maintain adequate synchronization despite the absence of physical cable connections.
2Measurement precision
If navigator echoes are acquired for timing correction, then measurement precision is improved, but scan time increases due to additional data acquisition
Solution Approach 1:
The imaging sequence is segmented into separate functional components: navigator echo acquisition for timing offset detection and main imaging data acquisition. By segmenting the sequence, the system can optimize each part independently - acquiring navigator echoes at minimal intervals between imaging lines, thereby achieving high timing correction accuracy without proportionally increasing total scan time.
Solution Approach 2:
The system applies partial action by acquiring navigator echoes only at specific strategic points in the imaging sequence rather than continuously. This selective acquisition provides sufficient timing information for accurate correction while minimizing the overhead time, avoiding the excessive action of continuous monitoring that would significantly extend scan time.
3Manufacturing precision
If phase errors are corrected retrospectively, then manufacturing precision is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
Navigator echoes serve as an intermediary element that bridges the timing mismatch between transmit and receive clocks. Instead of directly correcting the complex synchronization issues in the main imaging data, the system uses navigator echoes as a mediator to first characterize the timing offsets, then applies these characteristics as correction factors to the main data, simplifying the overall processing architecture.
Solution Approach 2:
The system replaces complex hardware-based timing synchronization mechanisms with software-based retrospective correction using navigator echoes. Instead of relying on hardware to maintain perfect synchronization between wireless transmit and receive clocks, the system uses signal processing to detect and correct timing errors after data acquisition, reducing device complexity while maintaining image quality.
Data Source
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AI summary
A method and apparatus correcting errors associated with timing offsets in radiofrequency coils. The method and apparatus include a memory element and a controller. The controller is configured to execute a set of instructions to receive data of a plurality of signals, the plurality of signals comprising at least one projection echo. The controller is also configured to identify a plurality of offsets of the plurality of signals based on the at least one projection echo. The controller is also configured to apply the plurality of offsets to a k-space of the plurality of signals.