Large improvement in RF magnetic fields and imaging SNR with whole-head high-permittivity slurry helmet for human-brain MRI applications at 7 T

Soo Han Soon, Xin Li, Matt Waks, Xiao Hong Zhu, Hannes M. Wiesner, Navid P. Gandji, Qing X. Yang, Michael T. Lanagan, Wei Chen

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To optimize the design and demonstrate the integration of a helmet-shaped container filled with a high-permittivity material (HPM) slurry with RF head coil arrays to improve RF coil sensitivity and SNR for human-brain proton MRI. Methods: RF reception magnetic fields ((Formula presented.)) of a 32-channel receive-only coil array with various geometries and permittivity values of HPM slurry helmet are calculated with electromagnetic simulation at 7 T. A 16-channel transmit-only coil array, a 32-channel receive-only coil array, and a 2-piece HPM slurry helmet were constructed and assembled. RF transmission magnetic field ((Formula presented.)), (Formula presented.), and MRI SNR maps from the entire human brain were measured and compared. Results: Simulations showed that averaged (Formula presented.) improvement with the HPM slurry helmet increased from 57% to 87% as the relative permittivity (εr) of HPM slurry increased from 110 to 210. In vivo experiments showed that the average (Formula presented.) improvement over the human brain was 14.5% with the two-piece HPM slurry (εr ≈ 170) helmet, and the average (Formula presented.) and SNR were improved 63% and 34%, respectively, because the MRI noise level was increased by the lossy HPM. Conclusion: The RF coil sensitivity and MRI SNR were largely improved with the two-piece HPM slurry helmet demonstrated by both electromagnetic simulations and in vivo human head experiments at 7 T. The findings demonstrate that incorporating an easily producible HPM slurry helmet into the RF coil array significantly enhances human-brain MRI SNR homogeneity and quality at ultrahigh field. Greater SNR improvement is anticipated using the less lossy HPM and optimal design.

Original languageEnglish (US)
Pages (from-to)1205-1219
Number of pages15
JournalMagnetic Resonance in Medicine
Volume93
Issue number3
DOIs
StatePublished - Mar 2025

All Science Journal Classification (ASJC) codes

  • Radiology Nuclear Medicine and imaging

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