Toward whole-cortex enhancement with an ultrahigh dielectric constant helmet at 3T

Christopher T. Sica, Sebastian Rupprecht, Ryan J. Hou, Matthew T. Lanagan, Navid P. Gandji, Michael T. Lanagan, Qing X. Yang

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To present a 3T brain imaging study using a conformal prototype helmet constructed with an ultra-high dielectric constant (uHDC; εr ~ 1000) materials that can be inserted into standard receive head-coils. Methods: A helmet conformal to a standard human head constructed with uHDC materials was characterized through electromagnetic simulations and experimental work. The signal-to-noise ratio (SNR), transmit efficiency, and power deposition with the uHDC helmet inserted within a 20-channel head coil were measured in vivo and compared with a 64-channel head coil and the 20-channel coil without the helmet. Seven healthy volunteers were analyzed. Results: Simulation and in vivo experimental results showed that transmit efficiency was improved by nearly 3 times within localized regions for a quadrature excitation, with a measured global increase of 58.21 ± 6.54% over 7 volunteers. The use of a parallel transmit spokes pulse compensated for severe degradation of B+ 1 homogeneity, at the expense of higher global and local specific absorption rate levels. A SNR histogram analysis with statistical testing demonstrated that the uHDC helmet enhanced a 20-channel head coil to the level of the 64-channel head coil, with the improvements mainly within the cortical brain regions. Conclusion: A prototype uHDC helmet enhanced the SNR of a standard head coil to the level of a high density 64-channel coil, although transmit homogeneity was compromised. Further improvements in SNR may be achievable with optimization of this technology, and could be a low-cost approach for future radiofrequency engineering work in the brain at 3T.

Original languageEnglish (US)
Pages (from-to)1123-1134
Number of pages12
JournalMagnetic Resonance in Medicine
Volume83
Issue number3
DOIs
StatePublished - Mar 1 2020

All Science Journal Classification (ASJC) codes

  • Radiology Nuclear Medicine and imaging

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