title: Comparison of 3.0 T proton magnetic resonance spectroscopy short and long echo-time measures of intramyocellular lipids in obese and normal-weight women.
abstract: OBJECTIVE
  To compare correlations of intramyocellular lipids (IMCL) measured by short and long echo-time proton magnetic resonance spectroscopy (1H-MRS) with indices of body composition and insulin resistance in obese and normal-weight women.
  
  
  METHODS
  We quantified IMCL of tibialis anterior (TA) and soleus (SOL) muscles in 52 premenopausal women (37 obese and 15 normal weight) using single-voxel 1H-MRS PRESS at 3.0 T with short (30 msec) and long (144 msec) echo times. Statistical analyses were performed to determine correlations of IMCL with body composition as determined by computed tomography (CT) and insulin resistance indices and to compare correlation coefficients from short and long echo-time data. Signal-to-noise ratio (SNR), linewidth, and coefficients of variation (CV) of short and long echo-time spectra were calculated.
  
  
  RESULTS
  Short and long echo-time IMCL from TA and SOL significantly correlated with body mass index (BMI) and abdominal fat depots (r = 0.32 to 0.70, P = <0.05), liver density (r = -0.39 to -0.50, P < 0.05), and glucose area under the curve as a measure of insulin resistance (r = 0.47 to 0.49, P < 0.05). There was no significant difference between correlation coefficients of short and long echo-time spectra (P > 0.5). Short echo-time IMCL in both muscles showed significantly higher SNR (P < 0.0001) and lower CVs when compared to long echo-time acquisitions. Linewidth measures were not significantly different between groups.
  
  
  CONCLUSIONS
  IMCL quantification using short and long echo-time 1H-MRS at 3.0 T is useful to detect differences in muscle lipid content in obese and normal-weight subjects. In addition, IMCL correlates with body composition and markers of insulin resistance in this population with no significant difference in correlations between short and long echo-times. Short echo-time IMCL quantification of TA and SOL muscles at 3.0 T was superior to long echo-time due to better SNR and better reproducibility.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA. mbredella@partners.org
authors.forename: Miriam A
authors.initials: MA
authors.lastname: Bredella
authors.forename: Reza Hosseini
authors.initials: RH
authors.lastname: Ghomi
authors.forename: Bijoy J
authors.initials: BJ
authors.lastname: Thomas
authors.forename: Karen K
authors.initials: KK
authors.lastname: Miller
authors.forename: Martin
authors.initials: M
authors.lastname: Torriani
mesh_terms: D000328:Adult; D000465:Algorithms; D001823:Body Composition; D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007333:Insulin Resistance; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009132:Muscles / Q000473:pathology; D009765:Obesity / Q000473:pathology*; D017697:Premenopause; D011522:Protons; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D011522:Protons