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Molecular, dynamic, and structural origin of inhomogeneous magnetization transfer in lipid membranes
Author(s) -
Swanson Scott D.,
Malyarenko Dariya I.,
Fabiilli Mario L.,
Welsh Robert C.,
Nielsen JonFredrik,
Srinivasan Ashok
Publication year - 2017
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.26210
Subject(s) - magnetization transfer , nuclear magnetic resonance , chemistry , magnetization , relaxation (psychology) , membrane , dipole , lamellar structure , biophysics , crystallography , magnetic resonance imaging , physics , magnetic field , biochemistry , biology , medicine , organic chemistry , quantum mechanics , neuroscience , radiology
Purpose To elucidate the dynamic, structural, and molecular properties that create inhomogeneous magnetization transfer (ihMT) contrast. Methods Amphiphilic lipids, lamellar phospholipids with cholesterol, and bovine spinal cord (BSC) specimens were examined along with nonlipid systems. Magnetization transfer (MT), enhanced MT (eMT, obtained with double‐sided radiofrequency saturation), ihMT (MT – eMT), and dipolar relaxation, T 1D , were measured at 2.0 and 11.7 T. Results The amplitude of ihMT ratio (ihMTR) is positively correlated with T 1D values. Both ihMTR and T 1D increase with increasing temperature in BSC white matter and in phospholipids and decrease with temperature in other lipids. Changes in ihMTR with temperature arise primarily from alterations in MT rather than eMT. Spectral width of MT, eMT, and ihMT increases with increasing carbon chain length. Conclusions Concerted motions of phospholipids in white matter decrease proton spin diffusion leading to increased proton T 1D times and increased ihMT amplitudes, consistent with decoupling of Zeeman and dipolar spin reservoirs. Molecular specificity and dynamic sensitivity of ihMT contrast make it a suitable candidate for probing myelin membrane disorders. Magn Reson Med 77:1318–1328, 2017. © 2016 International Society for Magnetic Resonance in Medicine