Low-cost gradient amplifiers for small MRI systems

Journal Article · 13 December 2021 · Journal of Magnetic Resonance

DOI: https://doi.org/10.1016/j.jmr.2021.107127 · OSTI ID:1977344

Evetts, Nathan ^[1]; Conradi, Mark S. ^[2]

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1. ABQMR, Inc., Albuquerque, NM (United States); OSTI
2. ABQMR, Inc., Albuquerque, NM (United States)

Here, we describe low-cost gradient amplifiers for small MRI systems, such as those based on small/medium permanent magnets. The requirements for MRI gradient amplifiers are quite similar to those of modestly priced audio stereo power amplifiers. Such amplifiers for sound service can be modified to be DC coupled, extending their response down to zero frequency, as needed for MRI gradient service. We describe such modifications to one unit (Samson Servo 600) and mention a commercially available modification of another. The 600 is capable of an output greater than ±8 A and ±60 V, much greater than our needs for a greenhouse MRI. Audio amplifiers can be used this way as controlled voltage (CV) gradient amplifiers, with acceptable performance because the gradient coils typically have short L/R time constants. Superior performance can be had by using a controlled current (CC) “front end”; the circuit of our simple front end is included. The complete 3-axis CC system costs about $1200.

• Research Organization: Texas A & M Univ., College Station, TX (United States). Texas A & M AgriLife Research
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• Grant/Contract Number: AR0000823
• OSTI ID: 1977344
• Journal Information: Journal of Magnetic Resonance, Journal Name: Journal of Magnetic Resonance Journal Issue: C Vol. 335; ISSN 1090-7807
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English