MRI RF Coil as Power Amplifier Inductor

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Solution Overview

Problem

Magnetic resonance imaging (MRI) scanners face inefficiencies due to the use of linear amplifiers, which require cooling systems, increasing the system's volume and cost, and reducing overall efficiency.

Innovation Solution

A high-efficiency power amplifier system for MRI scanners, utilizing a class E power amplifier configuration with a control module, signal generator, and coil, where the power amplifier includes an input inductance component, switching transistor, and capacitors, and the coil serves as both an inductor and capacitor, optimized for efficient RF pulse generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a linear amplifier is used to generate RF pulses in MRI scanner, then the amplifier can provide sufficient output power, but the amplifier generates excessive heat requiring cooling systems

Engineering Contradiction:

Improveoutput powerVSAvoidheat generation

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The patent changes the operating parameters of the amplifier by using a switching transistor that operates in saturation and cutoff regions rather than linear region, fundamentally changing how power is delivered to achieve high efficiency while maintaining sufficient output power

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs periodic switching action where the transistor is rapidly switched between saturation and cutoff states at RF frequencies, creating pulsed power delivery that maintains average power output while reducing continuous heat generation

Inventive Principle:

Principle #19Periodic action

2Temperature

If a cooling system is added to the amplifier, then heat dissipation is improved, but the volume of the MRI scanner increases

Engineering Contradiction:

Improveheat dissipationVSAvoidscanner volume

Core Design Contradiction:

TemperatureVSVolume of stationary object

Solution Approach 1:

The patent extracts and eliminates the cooling system from the amplifier design by adopting a class E configuration that inherently generates minimal heat, removing the need for separate cooling components and reducing overall scanner volume

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The amplifier design is self-cooling through its high efficiency operation, where the switching transistor and resonant circuit naturally dissipate minimal heat that does not require external cooling infrastructure

Inventive Principle:

Principle #25Self-service

3Temperature

If the amplifier is located outside the scanner room, then heat management is simplified, but the efficiency and cost of the system are reduced

Engineering Contradiction:

Improveheat managementVSAvoidsystem efficiency

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The patent converts the previously harmful heat generation issue into a benefit by using a high-efficiency class E amplifier that generates minimal heat, enabling the amplifier to be relocated inside the scanner room without heat management problems and thereby improving system efficiency

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent merges the amplifier with the RF coil assembly, combining the power amplification function with the transmission coil into a single integrated unit that can be positioned inside the scanner room, eliminating energy loss from external connections

Inventive Principle:

Principle #5Merging (Combining)

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 reduces heat generation and eliminates the need for external cooling systems, allowing the power amplifier to be placed within the scanner room, thereby enhancing efficiency and reducing costs while maintaining high performance.

Implementation Method 1

the coil serving as an inductor of the power amplifier

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

one or more capacitors capable of storing electric charges

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 3

a switching transistor controlled by the control module

Methodology Applied

Scientific EffectElectrical conduction and switching: Conduction (electrical)

Data Source

PatentUS10641847B2Magnetic resonance imaging scanner with coil serving as inductor of power amplifier

Publication Date: 2020.05.05 BILKENT UNIVERSITY

AI summary

According to an embodiment of the present disclosure, disclosed is an apparatus for generating a radio frequency (RF) pulse in a magnetic resonance imaging (MRI) scanner. The apparatus for generating a radio frequency (RF) pulse in a magnetic resonance imaging scanner includes: a control module controlling a power amplifier and a signal generator; the signal generator configured to generate a signal of a predetermined waveform based on control by the control module and supply the generated signal of the predetermined waveform to the power amplifier in electromagnetic connection therewith; a power amplifier amplifying the signal supplied from the signal generator based on the control by control module and outputting the amplified signal to a coil; and the coil serving as an inductor of the power amplifier and transferring the amplified signal to the object so that an object is excited.