MRI Diffusion Gradient Scheduling for Coil Thermal Management
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Solution Overview
Problem
Conventional magnetic resonance diffusion weighted imaging (DWI) methods generate excessive heat due to repeated use of diffusion gradients in short periods, leading to stress on gradient coils and amplifiers.
Innovation Solution
Applying a different diffusion gradient to each image slice during the same repetition time, rather than sequentially, to reduce heat generation and stress on gradient coils and amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same diffusion gradient is applied repeatedly to all image slices during sequenced repetition times, then diffusion weighted imaging data can be collected, but excessive heat is generated in the gradient coils and amplifiers
Solution Approach 1:
The patent segments the diffusion gradient application process by assigning different diffusion gradients to different image slices within the same repetition time. Instead of applying the same gradient repeatedly to all slices, each slice receives a unique gradient, distributing the thermal load across multiple gradient coil channels and reducing peak heat generation in any single channel.
Solution Approach 2:
The patent implements periodic variation of diffusion gradients across repetition times and slices. By cycling through different gradient directions and magnitudes in a systematic pattern, the system allows gradient coils to cool between high-power applications while maintaining comprehensive diffusion sampling across all slices.
2Productivity
If stronger gradient coils are used to improve imaging speed and capability, then faster scan times are achieved, but heat generation increases excessively
Solution Approach 1:
The patent changes the parameters of diffusion gradients (direction, magnitude, timing) across different slices and repetition times. By varying gradient strength and duration parameters systematically, the system achieves fast scan times with stronger effective gradients while distributing thermal stress through parameter modulation rather than sustained high-power application.
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 reduces heat generation and allows for stronger gradient coils and faster scan times while maintaining clinically useful diffusion weighted imaging capabilities.
Implementation Method 1
The magnet assembly is configured to apply a plurality of diffusion gradients to a plurality of image slices of the object during a plurality of repetition times
Implementation Method 2
The nuclei are excited by a radio frequency ('RF') signal/pulse transmitted by a RF coil at characteristics NMR (Larmor) frequencies. By spatially disturbing localized magnetic fields surrounding the subject and analyzing the resulting RF responses from the nuclei as the excited protons relax back to their lower energy normal state
Implementation Method 3
DWI utilizes gradient coils to generate diffusion gradients at the beginning of a pulse sequence to sensitize the acquired NMR signals to the movements of the molecules
Data Source
AI summary
Methods and systems for performing magnetic resonance diffusion weighted imaging of an object is provided. The method includes applying a plurality of diffusion gradients to a plurality of image slices of the object during a plurality of repetition times via an MRI system. A different diffusion gradient of the plurality is applied to each image slice during the same repetition time.