MRI RF Amplifier Gain Stabilization via Feedback Control
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Solution Overview
Problem
MRI apparatuses face fluctuations in RF pulse intensity due to temperature variations, leading to instability and artifacts in image quality, especially during prolonged imaging sessions.
Innovation Solution
An MRI apparatus with a processing circuitry that calculates and applies correction values to RF pulses based on the difference between output and reference values, ensuring consistent RF pulse intensity by promptly adjusting the amplifier input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If feedback control mechanism is used to adjust temperature, then temperature control is improved, but RF pulse intensity fluctuates due to synchronization with temperature variation
Solution Approach 1:
The patent implements a feedback control mechanism that monitors the actual output level of RF pulses and adjusts the RF amplifier gain accordingly. The control mechanism calculates the difference between the actual output level and the target output level, then modifies the gain to compensate for temperature-induced fluctuations, ensuring stable RF pulse intensity despite temperature variations.
Solution Approach 2:
The patent replaces the mechanical/thermal feedback control system with an electronic control system that directly monitors and adjusts RF amplifier gain through electronic circuits. This substitution allows for faster, more precise control of RF pulse intensity without the delays and synchronization issues inherent in thermal management systems.
2Ease of operation
If RF amplifier gain is adjusted based on output-input level difference, then gain control is improved, but control is influenced by temperature fluctuation synchronization
Solution Approach 1:
The patent implements a feedback control mechanism that monitors the actual output level of RF pulses and adjusts the RF amplifier gain accordingly. The control mechanism calculates the difference between the actual output level and the target output level, then modifies the gain to compensate for temperature-induced fluctuations, ensuring stable RF pulse intensity despite temperature variations.
Solution Approach 2:
The patent applies preliminary correction by adjusting the RF amplifier gain before temperature fluctuations can significantly impact the RF pulse intensity. The control mechanism proactively compensates for expected temperature-induced gain variations by pre-adjusting the gain setting based on monitored temperature trends and historical data.
3Duration of action of moving object
If imaging time is extended, then image quality is improved, but RF pulse intensity instability increases causing artifacts
Solution Approach 1:
The patent implements a feedback control mechanism that monitors the actual output level of RF pulses and adjusts the RF amplifier gain accordingly. The control mechanism calculates the difference between the actual output level and the target output level, then modifies the gain to compensate for temperature-induced fluctuations, ensuring stable RF pulse intensity despite temperature variations.
Solution Approach 2:
The patent maintains continuous monitoring and adjustment of RF amplifier gain throughout the imaging session. The control mechanism operates continuously to ensure that RF pulse intensity remains stable for the entire duration of the imaging protocol, allowing extended imaging times without the accumulation of intensity-related artifacts.
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 stabilizes RF pulse intensity, reducing artifacts and maintaining image quality by compensating for temperature-induced gain fluctuations in the RF amplifier, allowing for consistent output of RF pulses with intended intensity.
Implementation Method 1
an amplifier which amplifies RF pulses sequentially inputted from the generator
Implementation Method 2
adjusting its temperature by air cooling or water cooling
Data Source
AI summary
According to one embodiment, an MRI apparatus includes a generator, an amplifier, and processing circuitry. The generator sequentially generates RF pulses comprising an RF pulse train defined in a pulse sequence. The amplifier amplifies the RF pulses sequentially inputted from the generator. The processing circuitry calculates a correction value, each time an amplified RF pulse is outputted from the amplifier, based on a difference between an output value of the amplified RF pulse and a reference output value. Further, the processing circuitry applies the correction value promptly to an RF pulse to be inputted to the amplifier, the RF pulse to be inputted to the amplifier being included in the RF pulse train and being generated after an RF pulse corresponding to the amplified RF pulse used for calculation of the correction value is generated.