MRI Spin Echo Correction for Gradient Heating Artifacts
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Solution Overview
Problem
Magnetic resonance imaging (MRI) devices face challenges with temperature-induced changes in operating characteristics, leading to shifts in Larmor frequency and eddy current effects, which adversely affect image quality, particularly in spin echo sequences, causing mismatches in slice positions and k-space shifts.
Innovation Solution
A method for operating MRI devices that involves acquiring correction data during spin echo sequences to detect parameter shifts and apply compensation factors to maintain consistent imaging parameters, including adjustments to excitation pulses and readout frequencies, thereby ensuring accurate image acquisition and reducing artefacts like ghosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MRI devices operate gradient coils and power amplifiers during spin echo sequences, then imaging productivity is improved, but temperature increases causing parameter shifts and image quality degradation
Solution Approach 1:
The patent applies preliminary action by acquiring correction data at the beginning of the spin echo sequence (during the first pulse train) to detect parameter shifts before they significantly degrade image quality. This early detection allows the system to establish baseline correction factors that can be applied throughout the remaining imaging process, preventing temperature-induced artifacts rather than merely correcting them after they occur.
Solution Approach 2:
The patent implements feedback by continuously monitoring parameter shifts through correction data acquisition during the sequence and using detected shifts to adjust imaging parameters in real-time. The system measures actual parameter deviations from intended values and feeds this information back to correct subsequent imaging operations, creating a closed-loop control system that compensates for temperature effects dynamically throughout the scan.
2Measurement precision
If correction data is acquired during every pulse train, then measurement precision is improved, but productivity decreases due to additional readout time
Solution Approach 1:
The patent applies partial action by acquiring correction data during only the first pulse train or a limited subset of pulse trains rather than every single pulse train. This selective approach provides sufficient correction information to detect and compensate for parameter shifts while avoiding the excessive time overhead of continuous correction data acquisition, thereby maintaining both measurement precision and imaging productivity.
3Manufacturing precision
If compensation is applied to correct parameter shifts, then image quality is improved, but device complexity increases due to additional correction mechanisms
Solution Approach 1:
The patent introduces an intermediary correction data acquisition mechanism that mediates between the gradient coils and the imaging process. Rather than directly complicating the gradient coil design or power amplifier hardware, the system uses intermediate correction measurements and computational algorithms to detect and compensate for parameter shifts, thereby improving image quality through software-based correction rather than hardware modification.
4Productivity
If spin echo sequences are used with high gradient power, then productivity is improved, but parameter drift increases affecting slice position accuracy
Solution Approach 1:
The patent applies preliminary action by acquiring correction data during the first pulse train to detect parameter shifts before they significantly degrade slice position accuracy. This early detection establishes baseline correction factors that compensate for gradient heating effects throughout the sequence, maintaining slice positioning precision even when using high gradient power for fast imaging.
Solution Approach 2:
The patent implements feedback by using correction data to continuously monitor and detect parameter drifts in real-time during the spin echo sequence. The system measures actual deviations in slice position and other imaging parameters, then feeds this information back to adjust subsequent imaging operations, ensuring accurate slice positioning is maintained throughout the high-speed imaging process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves image quality by compensating for parameter shifts in real-time, reducing artefacts and maintaining intended imaging parameters, even under conditions of gradient heating, thus enhancing the reliability and accuracy of MRI images.
Implementation Method 1
magnetic resonance imaging (MRI) devices face challenges with temperature-induced changes in operating characteristics, leading to shifts in Larmor frequency
Implementation Method 2
a change in temperature can result in a change of eddy current effects which can for example lead to a shift in the k-space position of the recorded data
Data Source
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AI summary
The invention relates to a method (10) for operating an MRI device (1), the MRI device (1), and a corresponding computer program product (10) and storage medium (8). In the method (10) image data is acquired using a spin echo sequence with an additional readout (23, 26, 27) per pulse train (18, 19, 20) for acquiring correction data (21, 25). By comparing subsequent correction data (21, 25) of later pulse trains (18, 19, 20) to reference data acquired during a first pulse train (18, 19, 20) of the sequence a difference indicating a parameter shift is determined. A corresponding compensation is then automatically determined in dependence on the difference and is applied to a set of predetermined parameters for at least a respective next pulse train (18, 19, 20) and/or to the image data acquired in at least a respective next pulse train (18, 19, 20) of the sequence.