Meeting Banner
Abstract #2394

Super-Lorentzian Framework for Investigation of T2* Distribution in Myelin

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

Keywords

according additional agree alkyl alternatives ambient assuming attempts averaging bars bilayer bloom blue body bovine broad butcher chain characterizing chem chemical chemistry cholesterol choline complex component components composed comprised cord critical dehydrated described despite developing difficulty diffusion direct directly disorders dissolution distribution distributions effective expected expressed extract extracted extracts fits fitted fitting fractions framework free freshly full gradient harvested highlights highly immersed indicate indirect instruments intact intensities interactions intracellular investigation isotropic known laboratory labs lengths likely lipid lipids little local longer membrane methanol methylene methyls modality model moieties molecular moment motion needed numerous optimal peak peaked peaks phys posed potential previous prior problem protein proteins proton protons radiology rather rats reduce represent residual samples sampling scaled schizophrenia school sclerosis series short shorter sigma skewed spectra spectral spectrum spinal springer structural sucrose suggests super surface system temperature temple terminal theoretical theory thoracic tissue toward transfer ultra variation various water wide width widths