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On multiple alternating steady states induced by periodic spin phase perturbation waveforms
Author(s) -
Buračas Giedrius T.,
Jung Youngkyoo,
Lee Jongho,
Buxton Richard B.,
Wong Eric C.,
Liu Thomas T.
Publication year - 2012
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.23105
Subject(s) - waveform , steady state (chemistry) , alternating current , imaging phantom , perturbation (astronomy) , physics , nuclear magnetic resonance , synchronization (alternating current) , phase (matter) , signal (programming language) , temporal resolution , sensitivity (control systems) , optics , computer science , chemistry , mathematics , topology (electrical circuits) , voltage , electronic engineering , quantum mechanics , combinatorics , programming language , engineering
Direct measurement of neural currents by means of MRI can potentially open a high temporal resolution (10–100 ms) window applicable for monitoring dynamics of neuronal activity without loss of the high spatial resolution afforded by MRI. Previously, we have shown that the alternating balanced steady state imaging affords high sensitivity to weak periodic currents owing to its amplification of periodic spin phase perturbations. This technique, however, requires precise synchronization of such perturbations to the radiofrequency pulses. Herein, we extend alternating balanced steady state imaging to multiple balanced alternating steady states for estimation of neural current waveforms. Simulations and phantom experiments show that the off‐resonance profile of the multiple alternating steady state signal carries information about the frequency content of driving waveforms. In addition, the method is less sensitive than alternating balanced steady state to precise waveform timing relative to radiofrequency pulses. Thus, multiple alternating steady state technique is potentially applicable to MR imaging of the waveforms of periodic neuronal activity. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.