Iron mapping using the temperature dependency of the magnetic susceptibility. Issue 3 (17th April 2014)

• Record Type: Journal Article
• Authors: Birkl, Christoph; Langkammer, Christian; Krenn, Heinz; Goessler, Walter; Ernst, Christina; Haybaeck, Johannes; Stollberger, Rudolf; Fazekas, Franz; Ropele, Stefan
• Is Part Of: Magnetic resonance in medicine. Volume 73:Issue 3(2015:Mar.)
• Page Start: 1282
• Page End: 1288
• Publication Date: 2014-04-17
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.25236
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm25236-sec-0001" sec-type="section"> <title>Purpose</title> <p>The assessment of iron content in brain white matter (WM) is of high importance for studying neurodegenerative diseases. While R<sub>2</sub>* 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.</p> </sec> <sec id="mrm25236-sec-0002" sec-type="section"> <title>Theory and Methods</title> <p>We used unfixed human brain slices for relaxometry and calculated R<sub>2</sub>′ as a measure for microscopic susceptibility variations at several temperatures (4°C–37°C) at 3 Tesla. The temperature coefficient of R<sub>2</sub>′ (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.</p> </sec> <sec id="mrm25236-sec-0003" sec-type="section"> <title>Results</title> <p>In line with SQUID measurements, R<sub>2</sub>′ 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.</p> </sec> <sec id="mrm25236-sec-0004" sec-type="section"> <title>Conclusion</title> <p>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. <bold>Magn Reson Med 73:1282–1288, 2015. © 2014 Wiley Periodicals, Inc.</bold></p> </sec> </abstract>