In vivo human head MRI at 10.5T: A radiofrequency safety study and preliminary imaging results. Issue 1 (21st November 2019)

• Record Type: Journal Article
• Authors: Sadeghi‐Tarakameh, Alireza; DelaBarre, Lance; Lagore, Russell L.; Torrado‐Carvajal, Angel; Wu, Xiaoping; Grant, Andrea; Adriany, Gregor; Metzger, Gregory J.; Van de Moortele, Pierre‐Francois; Ugurbil, Kamil; Atalar, Ergin; Eryaman, Yigitcan
• Is Part Of: Magnetic resonance in medicine. Volume 84:Issue 1(2020)
• Page Start: 484
• Page End: 496
• Publication Date: 2019-11-21
• Subjects: 10.5T -- head imaging -- MRI -- radiofrequency safety -- ultra‐high field; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.28093
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: The purpose of this study is to safely acquire the first human head images at 10.5T. Methods: To ensure safety of subjects, we validated the electromagnetic simulation model of our coil. We obtained quantitative agreement between simulated and experimental B 1 + and specific absorption rate (SAR). Using the validated coil model, we calculated radiofrequency power levels to safely image human subjects. We conducted all experiments and imaging sessions in a controlled radiofrequency safety lab and the whole‐body 10.5T scanner in the Center for Magnetic Resonance Research. Results: Quantitative agreement between the simulated and experimental results was obtained including S‐parameters, B 1 + maps, and SAR. We calculated peak 10 g average SAR using 4 different realistic human body models for a quadrature excitation and demonstrated that the peak 10 g SAR variation between subjects was less than 30%. We calculated safe power limits based on this set and used those limits to acquire T2 ‐ and T 2 ∗ ‐weighted images of human subjects at 10.5T. Conclusions: In this study, we acquired the first in vivo human head images at 10.5T using an 8‐channel transmit/receive coil. We implemented and expanded a previously proposed workflow to validate the electromagnetic simulation model of the 8‐channel transmit/receive coil. Using the validated coil model, we calculated radiofrequency power levels to safely image human subjects.