Michael J. Wilhelm1, Henry H. Ong2, Felix W. Wehrli2
1Department of Chemistry, Temple University, Philadelphia, PA, United States; 2Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, PA, United States
Characterizing the T2* distribution of myelin is key to developing optimal ultra-short echo time (UTE) methods for direct myelin imaging. Previous attempts have used multi-exponential fitting of the FID, which theory shows is incorrect. Instead, myelin is a liquid crystalline lipid system that is described by a super-Lorentzian lineshape. Here, we use a super-Lorentzian framework to calculate T2* distributions from fits of 1H NMR spectra of myelin lipid extract and intact rat spinal cord. Both distributions are similar and have an approximate T2* range from 10μs to 10ms. Despite this large range, ~50% of the myelin lipid signal exhibits T2*≤20μs
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