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Iron mapping using the temperature dependency of the magnetic susceptibility
Author(s) -
Birkl Christoph,
Langkammer Christian,
Krenn Heinz,
Goessler Walter,
Ernst Christina,
Haybaeck Johannes,
Stollberger Rudolf,
Fazekas Franz,
Ropele Stefan
Publication year - 2015
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.25236
Subject(s) - quantitative susceptibility mapping , diamagnetism , magnetic susceptibility , paramagnetism , nuclear magnetic resonance , chemistry , relaxometry , white matter , squid , condensed matter physics , linear regression , magnetic resonance imaging , physics , spin echo , magnetic field , statistics , medicine , ecology , quantum mechanics , biology , radiology , mathematics
Purpose The assessment of iron content in brain white matter (WM) is of high importance for studying neurodegenerative diseases. While R 2 * mapping and quantitative susceptibility mapping is suitable for iron mapping in gray matter, iron mapping in WM still remains an unsolved problem. We propose a new approach for iron mapping, independent of diamagnetic contributions of myelin by assessing the temperature dependency of the paramagnetic susceptibility. Theory and Methods We used unfixed human brain slices for relaxometry and calculated R 2 ′ as a measure for microscopic susceptibility variations at several temperatures (4°C–37°C) at 3 Tesla. The temperature coefficient of R 2 ′ (TcR2p) was calculated by linear regression and related to the iron concentration found by subsequent superconducting quantum interference device (SQUID) magnetometry and by inductively coupled plasma mass spectrometry. Results In line with SQUID measurements, R 2 ′ mapping showed a linear temperature dependency of the bulk susceptibility with the highest slope in gray matter. Even in WM, TcR2p yielded a high linear correlation with the absolute iron concentration. Conclusion According to Curie's law, only paramagnetic matter exhibits a temperature dependency while the diamagnetism shows no effect. We have demonstrated that the temperature coefficient (TcR2p) can be used as a measure of the paramagnetic susceptibility despite of an unknown diamagnetic background. Magn Reson Med 73:1282–1288, 2015. © 2014 Wiley Periodicals, Inc.