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Related Experiment Video

Updated: May 13, 2026

Experimental Investigation of the Hierarchical Control in DC Microgrids Using a Real-time Simulator

Experimental Investigation of the Hierarchical Control in DC Microgrids Using a Real-time Simulator

Published on: February 14, 2025

A new approach to shimming: the dynamically controlled adaptive current network.

Chad T Harris¹, William B Handler, Blaine A Chronik

¹Department of Physics and Astronomy, Western University, London, Canada.

Magnetic Resonance in Medicine

|March 19, 2013

Summary

This study introduces a novel method using actively controlled switches to dynamically adjust current flow, significantly improving magnetic field homogeneity for magnetic resonance imaging (MRI) without artifacts.

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Area of Science:

Physics
Engineering
Medical Imaging

Background:

Magnetic field homogeneity is critical for accurate magnetic resonance imaging (MRI).
Existing methods for shimming magnetic fields can be static and may not adapt to specific imaging needs.
Dynamic control over field homogeneity offers potential for improved MRI performance.

Purpose of the Study:

To present a new approach for enhancing magnetic field homogeneity in MRI.
To enable dynamic and adaptive control of current distribution on a single surface.
To demonstrate the feasibility and effectiveness of this novel shimming technique.

Main Methods:

Computer simulations were used to model wire patterns designed with the boundary element method for inhomogeneity correction.
A prototype utilizing metal-oxide-semiconductor field-effect transistors was constructed and tested.
Field maps and region of interest histograms were compared before and after shim application.
Experimental results were validated against simulation data.

Main Results:

The developed wire patterns demonstrably increased magnetic field homogeneity across investigated regions.
The prototype successfully generated gradient and offset field profiles that matched simulation predictions.
No adverse imaging artifacts were observed, confirming the technique's compatibility with MRI.

Conclusions:

A method for precisely controlling current distribution on a surface has been successfully developed.
This technique holds significant potential for improving field homogeneity in targeted regions, especially for dynamic MRI applications.
The described approach is practical and achievable using current technological and manufacturing capabilities.