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Detection of subnanotesla oscillatory magnetic fields using MRI
Author(s) -
Jiang Xia,
Sheng Jingwei,
Li Huanjie,
Chai Yuhui,
Zhou Xin,
Wu Bing,
Guo Xiaodong,
Gao JiaHong
Publication year - 2016
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25553
Subject(s) - sensitivity (control systems) , excitation , magnetic field , scanner , pulse sequence , nuclear magnetic resonance , computer science , oscillation (cell signaling) , pulse (music) , physics , voltage , artificial intelligence , chemistry , electronic engineering , biochemistry , quantum mechanics , engineering
Purpose Direct mapping of neuronal currents using MRI would have fundamental impacts on brain functional imaging. Previous reports indicated that the stimulus‐induced rotary saturation (SIRS) mechanism had the best potential of direct detection of neural oscillations; however, it lacked the high‐sensitivity level needed. In this study, a novel strategy is proposed in an effort to improve the detection sensitivity. Methods In our modified SIRS sequence, an external oscillatory magnetic field is used as the excitation pulse in place of the standard 90‐degree excitation pulse. This approach could potentially lead to tens or even hundreds times of enhancement in the detection sensitivity for low field signals. It also helps to lower the physiological noise, allows for shorter pulse repetition time, and is less affected by the blood oxygen level. Results We demonstrate that a 100‐Hz oscillatory magnetic field with magnitude as low as 0.25 nanotesla generated in a current loop can be robustly detected using a 3‐Tesla MRI scanner. Conclusion The modified SIRS sequence offers higher detection sensitivity as well as several additional advantages. These promising results suggest that the direct detection of neural oscillation might be within the grasp of the current MRI technology. Magn Reson Med 75:519–526, 2016. © 2015 Wiley Periodicals, Inc.