Preclinical validation of a metasurface-inspired conformal elliptical-cylinder resonator for wrist MRI at 1.5 T

Abstract

Objective: To design a metasurface-inspired conformal elliptical-cylinder resonator (MICER) for wrist magnetic resonance imaging at 1.5 T and evaluate its potential for clinical applications.

Methods: An electromagnetic simulation was used to characterize the effect of MICER on radio frequency fields. A phantom and 14 wrists from 7 healthy volunteers were examined using a 1.5 T MRI system. The examination included T1-weighted spin echo, fat-saturation proton density-weighted fast spin echo, and three-dimensional T1-weighted gradient echo sequences. All scans were repeated using two methods: MICER combined with the spinal coil, which is a surface coil built-in examination table, and the 12-channel wrist array coil, to receive signals. Image signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated, and the differences between the two methods were compared using a paired Student's t-test.

Results: In the phantom study, the image obtained with MICER had a higher SNR compared to the image obtained with the 12-channel wrist coil. Almost all wrist tissues showed a higher SNR on the images obtained with MICER than on the images obtained with the 12-channel wrist coil (P < 0.05). And the CNR between wrist tissues on images obtained with MICER was higher than that obtained with the 12-channel wrist coil (P < 0.05).

Conclusions: The quality of the MRI using MICER is superior to that of the commercially available 12-channel wrist coil, indicating its potential value for clinical practice.

Keywords: Magnetic resonance imaging; Metasurface; Signal-to-noise ratio; Wrist.