Low-cost gradient amplifiers for small MRI systems

Area of Science:

• Engineering
• Medical Imaging
• Physics

Background:

• Gradient amplifiers are essential components for Magnetic Resonance Imaging (MRI) systems.
• Existing gradient amplifiers can be expensive, limiting the accessibility of small MRI systems.
• Audio stereo power amplifiers share similar technical requirements with MRI gradient amplifiers.

Purpose of the Study:

• To describe the modification of low-cost audio amplifiers for use as gradient amplifiers in small MRI systems.
• To present a cost-effective solution for building gradient amplifiers for research and educational MRI applications.
• To demonstrate the feasibility of using modified audio amplifiers for controlled voltage (CV) and controlled current (CC) gradient amplification.

Main Methods:

• Modification of a Samson Servo 600 audio amplifier to achieve DC coupling for MRI gradient service.
• Utilizing the inherent characteristics of audio amplifiers, such as their output capabilities (e.g., ±8 A and ±60 V).
• Incorporating a simple controlled current (CC) front-end circuit for superior performance compared to CV operation.

Main Results:

• Modified audio amplifiers can function effectively as gradient amplifiers for small MRI systems.
• The modified Samson Servo 600 demonstrated sufficient output capabilities for MRI applications.
• A complete 3-axis controlled current gradient system was developed with a total cost of approximately $1200.

Conclusions:

• Low-cost audio amplifiers represent a viable and economical alternative for gradient amplification in small-scale MRI systems.
• The described modifications enable the use of readily available audio equipment for specialized MRI applications.
• This approach significantly reduces the cost barrier for developing and deploying small MRI systems.