Active EMI Suppression System for a 50 mT Unshielded Portable MRI Scanner

Area of Science:

• Medical Imaging
• Biophysics
• Electrical Engineering

Background:

• Passive shielding hinders the mobility of portable MRI scanners.
• Electromagnetic interference (EMI) is a significant challenge for unshielded MRI systems.
• Human body coupling is identified as a primary path for EMI in portable MRI.

Purpose of the Study:

• To propose and validate an active EMI suppression (AES) system for portable MRI scanners.
• To enable the operation of portable MRI scanners in unshielded environments.
• To enhance the mobility and practicality of low-field MRI technology.

Main Methods:

• Analysis of interference transmission paths, identifying human body coupling.
• Development of a novel "ring-" shaped EMI receiving coil and ECG electrode patch.
• Utilizing k-space periphery data and least squares method to calculate transfer factors.
• Subtracting transferred reference EMI signals from MR signals for denoising.

Main Results:

• The AES system achieved a 96.8% interference suppression rate with the "ring-" shaped coil.
• Image Signal-to-Noise Ratio (SNR) after suppression was 97.2% of that from a shielded room.
• Successful in-vivo experiments on a 50 mT unshielded portable MRI scanner.

Conclusions:

• The proposed AES system effectively suppresses EMI in unshielded environments.
• The system ensures normal operation of portable MRI scanners.
• This technology offers a viable solution for truly mobile MRI applications.