RF Coil Electrical Coupling for MRI Motion Monitoring
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Solution Overview
Problem
Magnetic resonance imaging (MRI) quality is compromised by subject motion, particularly involuntary movements like respiration and cardiac activity, which are difficult to minimize without extending scan time or requiring complex external hardware.
Innovation Solution
A method and system that monitor subject motion by measuring the scattering of RF coils during imaging, using overlaid monitoring RF pulses to extract cardiac and respiratory signals, allowing for improved image reconstruction and reduced motion artifacts without additional external hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If breath holding is used to minimize diaphragm movement, then involuntary motion is reduced, but scan time is limited to at most 15 seconds
Solution Approach 1:
The system uses the subject's own body (specifically the diaphragm and heart) as the monitoring sensor. The RF coils detect changes in electrical coupling caused by respiratory and cardiac motion, eliminating the need for external monitoring hardware and breath-holding instructions, thereby removing the scan time limitation while maintaining motion control capability
Solution Approach 2:
The RF coils serve dual functions: they perform both imaging excitation and motion monitoring. By overlaying monitoring RF pulses on imaging pulse sequences and using the same coil array for both purposes, the system eliminates dedicated monitoring hardware and enables continuous motion tracking throughout the scan without extending scan time
2Reliability
If external hardware is used to control cardiac motion, then cardiac motion is monitored, but device complexity increases and setup time increases
Solution Approach 1:
The existing RF coil array performs both imaging and cardiac motion monitoring functions. By using the same hardware for dual purposes and overlaying monitoring pulses on imaging sequences, the system eliminates dedicated external monitoring hardware, reducing device complexity and setup time while maintaining cardiac motion control capability
Solution Approach 2:
The system merges the imaging and motion monitoring functions into a single integrated process. The RF coils, pulse sequences, and data acquisition systems are combined to simultaneously perform both imaging excitation and cardiac motion detection, eliminating the need for separate external monitoring systems
3Measurement precision
If monitoring RF pulses are overlaid on imaging pulse sequences, then motion monitoring is achieved, but interference with imaging may occur
Solution Approach 1:
The system uses periodic monitoring RF pulses overlaid on periodic imaging pulse sequences. By carefully timing and spacing these periodic pulses, the system achieves continuous motion monitoring while allowing the imaging sequence to proceed uninterrupted, minimizing interference through rhythmic synchronization
Solution Approach 2:
The monitoring RF pulses use different parameters (frequency, amplitude, duration) than the imaging pulses. This parameter differentiation allows the system to distinguish between monitoring and imaging signals, enabling motion detection without significant interference with the 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 enables simultaneous measurement of subject motion during MRI scans, improving image quality by minimizing blurring and artifacts, reducing setup time, and providing high signal-to-noise ratio without prolonging the image sequence or inducing significant interference.
Implementation Method 1
measuring how external RF coils couple to the subject and to one another during imaging
Implementation Method 2
Changes in position influence this coupling and are reflected in the scattering of the network of coils
Implementation Method 3
one or more radio frequency (RF) pulses are generated that excite and align proton spins
Implementation Method 4
Following the RF pulse(s), protons relax, generating RF emissions that are detected by receivers in the scanner
Data Source
AI summary
Described herein are methods for monitoring and/or extracting subject motion from multi-channel electrical coupling in imaging of the subject, in particular in magnetic resonance (MR) imaging of the subject.