Low eddy current RF shielding enclosure designs for 3T MR applications

Area of Science:

• Medical Physics
• Biomedical Engineering
• Magnetic Resonance Imaging

Background:

• Magnetic resonance-compatible medical devices require robust shielding to prevent electromagnetic interference within the MRI environment.
• Ensuring the integrity of both the MRI system and the medical device is paramount for accurate diagnostic imaging.

Purpose of the Study:

• To evaluate the radiofrequency (RF) shielding effectiveness and gradient-induced eddy current performance of various shielding configurations for positron emission tomography (PET) detectors.
• To identify optimal shielding solutions applicable to a broad range of MR-compatible devices.

Main Methods:

• Six shielding configurations were designed using materials like copper, phosphor bronze mesh (PBM), and carbon fiber composite (CFC) with varying thicknesses and patterns.
• Tests were conducted to measure RF shielding effectiveness and assess gradient-induced eddy current impacts.

Main Results:

• Solid copper and PBM configurations demonstrated superior RF shielding effectiveness (>15 dB) compared to carbon fiber composite and segmented designs.
• Solid copper shielding exhibited significantly worse gradient-induced eddy current performance (up to 3.89 dB) than segmented copper, PBM, and CFC configurations.

Conclusions:

• Phosphor bronze mesh (PBM) emerged as the only shielding material demonstrating positive outcomes for both RF shielding effectiveness and gradient-induced eddy current performance.
• The findings guide the selection of appropriate shielding for MR-compatible devices to mitigate electromagnetic interference and artifacts.