Orientation of lipid strands in the extracellular compartment of muscle: Effect on quantitation of intramyocellular lipids
Abstract
Single‐voxel 1H NMR spectra from gastrocnemius and soleus muscle were acquired in healthy volunteers at 7T with the objective of measuring the concentration of intramyocellular lipid [IMCL] (note: throughout this article, square brackets indicate concentration). However, significant asymmetry in the resonance assigned to the methylene protons (‐CH2‐)n in extramyocellular lipids (EMCL) interfered with fitting the spectra. Since muscle fibers in these tissues are generally not parallel to B0, the influence of variable orientation in strands of extracellular fat was examined using a mathematical model. Modest variation in orientation produced asymmetric lineshapes that were qualitatively similar to typical observations at 7T. Analysis of simulated spectra by fitting with a Voigt function overestimated [IMCL]/[EMCL] except when EMCL fibers were nearly parallel to B0. Estimates of [IMCL]/[EMCL] were improved by including variations in fiber orientation in the lineshape analysis (fiber orientation modeling, or FOM). Calculated [IMCL] using FOM, 4.8 ± 2.2 mmol/kg wet weight, was lower compared to most previous reports in soleus. Magn Reson Med 61:16–21, 2009. © 2008 Wiley‐Liss, Inc.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 18, 2008
- Source ID
- 10.1002/mrm.21831
Entities
People
- A. Dean Sherry
- Anthony Khuu
- Craig R. Malloy
- Donald Woessner
- Ivan Dimitrov
- James Murdoch
- Jimin Ren
Organizations
- National Institutes of Health
- United States Department of Defense