Multi-frequency MRI Excitation Coils with On-Coil Amplification
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Solution Overview
Problem
Conventional MRI systems face challenges with scaling, fidelity, synchronization, and efficiency in parallel transmission techniques due to issues with cabling duplication, power management, and interactions between multiple coils, leading to limited multi-frequency experimentation and poor performance.
Innovation Solution
The implementation of a current-mode class-D amplifier topology with on-coil switched-mode amplification and digital control, using field effect transistors (FETs) and L-C coils with different resonance frequencies, allows for improved synchronization and isolation between coils, enabling higher power efficiency and fidelity in parallel MRI transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple individually powered RF transmitters are used for parallel transmission, then signal reception speed is improved, but system complexity and cabling duplication increase
Solution Approach 1:
The patent combines multiple RF transmitter channels into a single integrated system with shared power distribution and control architecture. The parallel transmission capability is maintained through software-defined radio technology, allowing multiple virtual channels to operate simultaneously over shared physical infrastructure, thereby reducing cabling duplication and system complexity while preserving high signal reception speed.
Solution Approach 2:
The RF transmitter system is designed with multi-functionality to handle multiple frequencies and transmission modes through a single unified platform. The system can dynamically configure different transmission patterns and frequency combinations, eliminating the need for separate dedicated transmitters for each function and reducing overall system complexity.
2Adaptability or versatility
If multiple coils are tuned to different frequencies for multi-frequency excitation, then excitation capability is improved, but coil interactions cause tuning issues
Solution Approach 1:
The system implements dynamic tuning capabilities where coil resonant frequencies can be adjusted in real-time through variable capacitors or inductors. This allows the system to optimize frequency assignments based on current experimental requirements while maintaining stable operation by actively compensating for interactions between coils through feedback control mechanisms.
Solution Approach 2:
The patent incorporates feedback mechanisms that monitor coil interactions and automatically adjust tuning parameters to maintain optimal performance. Sensors detect frequency drift and coupling effects between coils, and the system responds by modifying capacitor values or transmission timing to preserve tuning stability across all operating frequencies.
3Ease of manufacture
If conventional analog RF transmitters are used, then implementation is straightforward, but power distribution management becomes complicated
Solution Approach 1:
The patent replaces traditional analog RF transmission hardware with software-defined radio technology, where digital signal processing algorithms generate and modulate RF signals. This substitution eliminates complex analog power distribution networks by using digitally controlled power amplifiers that can be precisely managed through software, simplifying power distribution while maintaining ease of implementation through programmable control.
4Productivity
If multiple transmitters operate in parallel, then transmission speed is improved, but synchronization becomes difficult
Solution Approach 1:
The system employs feedback mechanisms that continuously monitor the phase and timing of signals from multiple transmitters. A central controller adjusts transmission timing based on real-time measurements, ensuring precise synchronization across all parallel channels while maintaining high transmission speed through coordinated operation.
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 solution achieves higher efficiency, reduced interference, and improved amplitude and phase control, enabling more effective multi-frequency excitation and faster scan times, thus enhancing the capability for multi-frequency experimentation in MRI systems.
Implementation Method 1
The L-C coil includes an inductor and a capacitor. The L-C coil has a resonance frequency.
Implementation Method 2
an apparatus includes an RF coil having an amplifier
Data Source
AI summary
Devices, systems, methods, and other embodiments associated with magnetic resonance imaging (MRI) are described. In one embodiment, an apparatus includes an RF coil for use in multi-nuclear excitation in magnetic resonance imaging (MRI). The RF coil includes a set of two or more L-C coils. Members of the set of two or more L-C coils have individual resonance frequencies. An RF amplifier is placed near the RF coil. The RF amplifier is controllable to selectively produce the individual resonance frequency of a member of the set of two or more L-C coils based, at least in part, on a digital input provided to the RF amplifier.