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Susceptibility gradient mapping (SGM): A new postprocessing method for positive contrast generation applied to superparamagnetic iron oxide particle (SPIO)‐labeled cells
Author(s) -
Dahnke Hannes,
Liu Wei,
Herzka Daniel,
Frank Joseph A.,
Schaeffter Tobias
Publication year - 2008
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.21478
Subject(s) - imaging phantom , contrast (vision) , superparamagnetism , gradient echo , pulse sequence , nuclear magnetic resonance , dephasing , magnetic susceptibility , in vivo , materials science , quantitative susceptibility mapping , image contrast , chemistry , computer science , magnetic resonance imaging , physics , artificial intelligence , optics , magnetic field , radiology , crystallography , magnetization , medicine , biology , condensed matter physics , microbiology and biotechnology , quantum mechanics
Abstract Local susceptibility gradients result in a dephasing of the precessing magnetic moments and thus in a fast decay of the NMR signals. In particular, cells labeled with superparamagnetic iron oxide particles (SPIOs) induce hypointensities, making the in vivo detection of labeled cells from such a negative image contrast difficult. In this work, a new method is proposed to selectively turn this negative contrast into a positive contrast. The proposed method calculates the susceptibility gradient and visualizes it in a parametric map directly from a regular gradient‐echo image dataset. The susceptibility gradient map is determined in a postprocessing step, requiring no dedicated pulse sequences or adaptation of the sequence before and during image acquisition. Phantom experiments demonstrated that local susceptibility differences can be quantified. In vivo experiments showed the feasibility of the method for tracking of SPIO‐labeled cells. The method bears the potential also for usage in other applications, including the detection of contrast agents and interventional devices as well as metal implants. Magn Reson Med 60:595–603, 2008. © 2007 Wiley‐Liss, Inc.