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Abstract #4075

Open-Source, High-Efficiency, Easily-Reconfigurable Switch-mode Current Driver for B0 Shimming and Local Field Control

Ishaan Govindarajan1, Donald Straney2, Juan Rivas-Davilla3, Kawin Setsompop4, Hong En Chew3, Thomas Witzel5, Lawrence Wald6, Yulin Chang7, and Jason P Stockmann2
1Massachusetts Institute of Technology, Cambridge, MA, United States, 2Athinoula A. Martinos Center for Biomedical Imaging, Cambridge, MA, United States, 3Electrical Engineering, Stanford University, Stanford, CA, United States, 4Radiological Sciences Laboratory, Stanford University, Stanford, CA, United States, 5Q Bio, Inc., San Carlos, CA, United States, 6Massachusetts General Hospital, Charlestown, MA, United States, 7Siemens Healthcare, Charlestown, MA, United States

Synopsis

Keywords: New Devices, New Devices

Motivation: Multi-coil arrays have demonstrated utility for higher-order B0 shimming, spatial encoding, and local field control. However, existing amplifiers used to drive these coils typically trade off efficiency and imaging noise.

Goal(s): Demonstrate a proof-of-concept amplifier with both high efficiency and low imaging noise, while being easily reconfigurable for different loads impedances.

Approach: A switch-mode amplifier with highly-integrated power stages, 6th-order LC filtering, and fully-digital control was developed. Its thermal performance, dynamic performance, and impact on imaging noise was tested.

Results: Our amplifier demonstrated heatsink-free 10ADC drive capability, <25μs step response rise-times with multiple loads, acceptable disturbance rejection, all while minimally impacting image quality.

Impact: We have demonstrated an open-source, proof-of-concept amplifier achieving power efficiencies of switch-mode designs while maintaining imaging noise levels akin to linear designs. Such an amplifier unblocks novel spatial encoding techniques and local field control applications. Development is active and ongoing.

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Keywords