Electromagnetic Noise Characterization and Suppression in Low-Field MRI Systems

Area of Science:

• Medical Imaging
• Biophysics
• Electrical Engineering

Background:

• Low-field MRI systems are susceptible to electromagnetic interference (EMI).
• Operating near the thermal noise limit is crucial for optimal signal-to-noise ratio (SNR).
• Existing protocols for noise suppression in low-field MRI are often impractical.

Purpose of the Study:

• To develop and validate a practical protocol for identifying and suppressing electromagnetic noise in low-field MRI systems.
• To enable low-field MRI operation close to the theoretical thermal noise limit.
• To provide guidance for integrating additional system components without compromising SNR.

Main Methods:

• A systematic, stepwise methodology was developed.
• Diagnostic measurements, hardware isolation, and best practices for cabling and shielding were employed.
• Noise measurements were conducted during incremental system assembly, with and without a human subject.

Main Results:

• Key sources of EMI were identified and their impact quantified.
• Final system configurations achieved noise levels within 1.5x the theoretical thermal bound with a subject present.
• Image reconstructions demonstrated a direct correlation between system noise and image quality.

Conclusions:

• The proposed protocol enables low-field MRI systems to operate near fundamental noise limits under realistic conditions.
• The framework offers guidance for integrating new components like gradient drivers and automatic tuning networks.
• Successful noise suppression leads to improved image quality and system performance.