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Quantifying the Relative Thickness of Conductive Ferromagnetic Materials Using Detector Coil-Based Pulsed Eddy Current Sensors
Published on: January 16, 2020
Avoiding eddy-current problems in ultra-low-field MRI with self-shielded polarizing coils
Jaakko O Nieminen1, Panu T Vesanen, Koos C J Zevenhoven
1Department of Biomedical Engineering and Computational Science, Aalto University School of Science, P.O. Box 12200, FI-00076 AALTO, Finland. jaakko.nieminen@aalto.fi
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|July 26, 2011
Summary
Researchers developed self-shielded polarizing coils for ultra-low-field magnetic resonance imaging (ULF MRI). This innovation significantly reduces eddy currents in magnetic shielded rooms, enabling stronger polarizing fields for improved ULF MRI performance.
Area of Science:
- Medical Imaging
- Biophysics
- Electrical Engineering
Background:
- Ultra-low-field magnetic resonance imaging (ULF MRI) utilizes sensitive superconductive sensors but requires rapid switching of strong prepolarizing magnetic fields.
- Conventional polarizing coils in ULF MRI systems induce eddy currents within magnetically shielded rooms (MSRs).
- These eddy currents generate secondary magnetic fields that interfere with ULF MRI signal acquisition and sensor performance.
Purpose of the Study:
- To introduce a novel method for designing self-shielded polarizing coils specifically for ULF MRI applications.
- To mitigate the adverse effects of eddy currents generated by polarizing coils within MSRs.
- To enhance the capabilities of ULF MRI by enabling the use of stronger and more spatially uniform polarizing fields.
Main Methods:
- Design and implementation of self-shielded polarizing coil configurations for ULF MRI.
- Experimental evaluation of the designed coils within a magnetically shielded room environment.
- Measurement and analysis of eddy current induced magnetic fields and their impact on ULF MRI signal acquisition.
Main Results:
- The developed self-shielded polarizing coils substantially reduced the magnetic fields generated by eddy currents.
- Experimental data confirmed a significant decrease in eddy current interference compared to traditional unshielded coils.
- The shielding technique allowed for the application of stronger and broader polarizing fields in ULF MRI.
Conclusions:
- Self-shielded polarizing coils offer an effective solution to minimize eddy current effects in ULF MRI systems housed in MSRs.
- This advancement facilitates improved ULF MRI performance by enabling higher-strength and more uniform prepolarization.
- The presented technique broadens the potential applications and enhances the feasibility of ULF MRI.
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