Conduction-Cooled RF Coil Subsystem for Low-Field MRI
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Solution Overview
Problem
Low-field and ultra-low-field MRI systems face significant challenges in achieving high signal-to-noise ratio (SNR) performance due to the approximately linear relationship between SNR and magnetic field strength, which is not improved by increasing field strength, and are critical for improving image quality and scan speed.
Innovation Solution
A conduction-cooled radiofrequency (RF) coil subsystem is introduced, featuring a RF coil module with a cryocooler and thermal conduction line to cool RF instrumentations such as transceiver coils, receiver coils, and preamplifiers, significantly enhancing SNR performance by reducing noise and resistive losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional RF coils are used in low-field MRI systems, then the system structure remains simple, but the signal-to-noise ratio is extremely low
Solution Approach 1:
The patent applies parameter changes by cooling the RF coil to cryogenic temperatures (e.g., 4K), which fundamentally changes the thermal state of the system. This temperature parameter change reduces thermal noise and resistive losses, thereby improving the signal-to-noise ratio by a factor of √N compared to conventional room-temperature coils, while maintaining compatibility with low-field MRI systems
Solution Approach 2:
The patent introduces a cryocooler as an intermediary device between the RF coil and the environment. This cryocooler acts as a thermal mediator that actively removes heat from the RF coil, enabling cryogenic operation without requiring complex liquid helium infrastructure, thus improving SNR while controlling system complexity
2Measurement precision
If RF coil temperature is reduced to improve SNR, then signal-to-noise ratio increases by factor of √N, but thermal management complexity increases
Solution Approach 1:
The patent applies self-service by designing the cryocooler system to be self-contained and self-regulating. The cryocooler automatically maintains the RF coil at cryogenic temperatures through closed-loop thermal management, eliminating the need for external liquid helium supply systems and manual temperature control, thus achieving SNR improvement while keeping thermal management practical
Solution Approach 2:
The patent replaces complex mechanical thermal management systems (liquid helium dewars, manual pumping systems) with a solid-state cryocooler system. This substitution eliminates the need for liquid cryogens and complex mechanical infrastructure, achieving cryogenic cooling through solid-state thermoelectric or cryogenic compressor mechanisms, thereby improving SNR while reducing operational complexity
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
The solution achieves at least twice the SNR of conventional MRI systems, enabling improved imaging capabilities at low and ultra-low field strengths by effectively cooling RF components, thus addressing the low SNR issue.
Implementation Method 1
a thermal conduction line thermally connected between the cryocooler and the RF instrumentation... The thermal conduction line is thermally coupled to the cryocooler... to conduction cool the RF instrumentation
Data Source
AI summary
A conduction-cooled radiofrequency coil subsystem of MRI system with high signal-to-noise ratio imaging capability at low field and/or ultra-low field. The conduction-cooled RF coil subsystem includes a radiofrequency (RF) coil module having at least one RF instrumentation; a cryocooler; and a thermal conduction line thermally connected between the cryocooler and the RF instrumentation. The RF coil module further includes a housing defining a thermally insulated vessel for accommodating the RF instrumentation. The thermal conduction line is thermally coupled to the cryocooler which is located outside the housing of the RF coil module and the RF instrumentation in the thermally insulated vessel to conduction cool the RF instrumentation. The at least one RF instrumentation includes one or more of an RF transceiver coil, an RF receiver coil, an RF preamplifier and an RF electronics module.