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Novel MRI contrast development by lock‐in suppression
Author(s) -
Chen YuWen,
Hsu ChouHsiung,
Hwang Dennis W.
Publication year - 2014
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.25162
Subject(s) - contrast (vision) , dynamic contrast , spatial frequency , image contrast , lock (firearm) , nuclear magnetic resonance , sensitivity (control systems) , bandwidth (computing) , magnetic resonance imaging , computer science , physics , optics , radiology , medicine , electronic engineering , telecommunications , mechanical engineering , engineering
Purpose The goal of this study is to develop novel MR contrast by frequency lock‐in technique. Methods An electronic feedback device that can control the frequency and bandwidth of the feedback RF field is presented. In this study, the effects of lock‐in suppressed imaging are discussed both theoretically and experimentally. Results Two important imaging experiments were performed. The first experiment used magnetizations with the same central frequency but different frequency distributions and was compared with MR images obtained with T 2 contrast agents. Lock‐in suppressed images showed an improvement in contrast relative to the conventional imaging method. The second experiment used magnetizations with small shifts in frequency and a broad frequency distribution. This is helpful for differentiating between small structural variations in biological tissues. The contrast achieved in in vivo tumor imaging using the lock‐in suppressed technique provide higher spatial resolutions and discriminate the regimes of necrosis and activation consistent with pathologic results. Conclusion Lock‐in suppressed imaging introduces a conceptually new approach to MRI. Heightened sensitivity to underlying susceptibility variations and their relative contribution to total magnetization may thus be achieved to yield new and enhanced contrast. Magn Reson Med 71:1676–1681, 2014. © 2014 Wiley Periodicals, Inc.