Year: 2026
Type: article
Abstract: In this paper, we propose Frequency Selective Surface (FSS) as an radiofrequency (RF) shield for coils in portable MRI systems. The new approach aims to obtain enhancement of coil sensitivity compared to traditional copper shields to improve the signal-to-noise ratio (SNR). A high-pass inductive FSS shield is designed for a solenoid working for a 100 mT portable MRI scanner with a transversal main magnetic field. The effectiveness of the shield is analyzed in terms of B 1 sensitivity and shielding effectiveness. An equivalent circuit model pairing the FSS with the solenoid coil is introduced to facilitate the analysis of the effects of a FSS shield. Evaluations are conducted through simulations using CST software, analytical calculations, on-bench experiments and MRI scans of a cylindrical phantom and a small apple in a 100 mT portable MRI scanner. Another solenoid of the same dimension with a copper shield and one without a shield are included in the study for comparison. The FSS-shielded solenoid shows a good combination of B 1 sensitivity and shielding effectiveness. The results demonstrate The FSS shield can suppress over 90% of noise with less compromise in B 1 sensitivity than copper shields. Consequently, the MRI images of a cylindrical phantom and an apple at 100 mT using the proposed FSS-shielded solenoid shows the highest SNR compared to the other two cases. Meanwhile, the accuracy of the proposed equivalent model for the FSS-shielded coil is validated. This study shows that an FSS shield with inductive mesh-grids around a solenoid coil is a promising approach to increase the SNR compared with copper-shielded at 100 mT. The study can be extended to other types of FSS for compact shielding of RF coils.
Source: Journal of Magnetic Resonance
Language: English
Subfield: Radiology, Nuclear Medicine and Imaging
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $3,500
OpenAlex ID: W7214538786