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Multi‐chromatic magnetic resonance imaging using frequency lock‐in suppression
Author(s) -
Chen YuWen,
Hwang Dennis W.
Publication year - 2015
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3361
Subject(s) - imaging phantom , bandwidth (computing) , radio frequency , contrast (vision) , nuclear magnetic resonance , optics , center frequency , chromatic scale , spatial frequency , magnetic resonance imaging , materials science , physics , computer science , telecommunications , band pass filter , medicine , radiology
This study developed a multi‐chromatic MR contrast using the frequency lock‐in technique. An electronic feedback device that generates a specific narrow‐frequency‐bandwidth RF field is presented. The effects of this RF field on MR images are assessed both theoretically and experimentally. Spectroscopy and imaging experiments were performed. Frequency tuning allowed the selected spectral peak to be suppressed. Phantom tests using methanol, ethanol, and water showed different contrasts using different feedback RF field frequencies. The frequency lock‐in was also found to help differentiate among the small structural variations in biological tissues. The contrast achieved in in vivo mouse brain imaging using the lock‐in suppressed technique indicated a better spatial discrimination when compared with that achieved using conventional imaging methods, especially in the hippocampus region. Selective lock‐in suppressed imaging is a new approach to provide frequency information in MRI; rather than determining the evolution of image contrast over time, this approach allows small susceptibility variations to be distinguished by tuning the frequency of the narrow‐bandwidth lock‐in RF field. A new and enhanced contrast can be achieved using this technique. Copyright © 2015 John Wiley & Sons, Ltd.