MRI Coil Sensitivity Map Reacquisition via Position Monitoring
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Solution Overview
Problem
Magnetic resonance imaging (MRI) techniques using multiple coil elements face artifacts and reduced image quality due to changes in patient or coil position during data acquisition, leading to incorrect sensitivity maps and potential misdiagnoses.
Innovation Solution
Implement a method that measures reference and comparison information on patient and coil positions before and during MRI acquisition, triggering reacquisition of sensitivity maps if deviations exceed a threshold, using a navigator sequence to monitor changes and maintain accurate calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If sensitivity maps are acquired once at the start of the examination procedure, then the calibration procedure is efficient and quick, but position changes during acquisition lead to incorrect sensitivity maps and image artifacts
Solution Approach 1:
The system continuously monitors patient and coil positions during the MRI acquisition procedure using reference information and comparison information. When position deviations exceed a threshold, the system triggers a reacquisition of sensitivity maps, creating a feedback loop that maintains accuracy without requiring continuous calibration
Solution Approach 2:
The calibration system transitions from a static single-point calibration to a dynamic adaptive calibration process. The decision to reacquire sensitivity maps is made dynamically based on real-time position monitoring, allowing the system to adapt to position changes while minimizing unnecessary recalibrations
2Reliability
If sensitivity maps are reacquired frequently to maintain accuracy, then image quality is maintained, but the overall acquisition time increases significantly
Solution Approach 1:
The system uses threshold-based feedback control to determine when recalibration is necessary. By comparing reference position information with comparison position information and only triggering reacquisition when deviations exceed the threshold, the system maintains image quality while avoiding unnecessary recalibrations that would waste time
Solution Approach 2:
The system changes the calibration state parameter (sensitivity map acquisition) based on monitored position parameters. Instead of continuous recalibration, the system transitions between calibrated and uncalibrated states based on position deviation thresholds, optimizing the balance between quality and time
3Measurement precision
If position monitoring is performed continuously during acquisition, then position changes are detected accurately, but the complexity of the measurement system increases
Solution Approach 1:
The system uses reference information and comparison information as intermediary representations of position data. Rather than implementing complex real-time tracking, the system uses simplified position indicators that can be compared to detect meaningful changes, reducing measurement system complexity while maintaining detection accuracy
Data Source
AI summary
A method for operating a magnetic resonance device includes using an acquisition technique using a plurality of coil elements of a transmit and/or receive coil in parallel. For each coil element, a sensitivity map describing the spatial sensitivity of the respective coil element is acquired at the start of the acquisition procedure and used in the reconstruction of a magnetic resonance image dataset from the magnetic resonance data. Magnetic resonance data of the individual coil elements is thus merged. Reference information indicating the position of the patient and/or of the coil elements is measured at the start of the examination procedure. Comparison information supplementary thereto is measured during the acquisition procedure. A reacquisition of at least a portion of the sensitivity maps is performed if at least one recalibration criterion describing a deviation exceeding a threshold value is fulfilled in a comparison of the comparison data with the reference data.