title: Long echo time proton magnetic resonance spectroscopy for estimating relative measures of lipid unsaturation at 3 T.
abstract: OBJECTIVE
  To examine the behavior of lipid olefinic and diallylic resonances as a function of PRESS (point resolved spectroscopy) echo time (TE) to determine an optimal long TE value for their measurement at 3 T.
  
  
  METHODS
  Experiments were conducted on nine oils (almond, canola, cod liver, corn, linseed, peanut, sesame, sunflower, and walnut oil) and on vertebral and tibial bone marrow in vivo at 3 T. The methylene (or methyl + methylene), diallylic, and olefinic resonances were measured with PRESS with multiple TEs.
  
  
  RESULTS
  J-coupling evolution effects on the olefinic and diallylic peaks appeared to be minimized when TE = 200 msec. The TE = 200 msec olefinic/methylene and diallylic/methylene peak area ratios calculated for each oil correlated well with ratios deduced from oil compositions in the literature (R(2) = 0.92 and 0.98 for the olefinic and diallylic protons, respectively). In addition, the relative amounts of bone marrow unsaturation of vertebral and tibial bone marrow inferred from the TE = 200 msec olefinic/(methyl + methylene) peak area ratio agreed with values estimated from the literature.
  
  
  CONCLUSIONS
  A PRESS sequence with a long TE value of 200 msec is suitable for determining relative amounts of lipid unsaturation at 3 T.
authors.affiliation: Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Alice
authors.initials: A
authors.lastname: Troitskaia
authors.forename: B Gino
authors.initials: BG
authors.lastname: Fallone
authors.forename: Atiyah
authors.initials: A
authors.lastname: Yahya
mesh_terms: D000328:Adult; D000475:Alkenes / Q000032:analysis; D001853:Bone Marrow / Q000737:chemistry*; D003060:Cod Liver Oil / Q000032:analysis; D004042:Dietary Fats, Unsaturated / Q000032:analysis*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D010938:Plant Oils / Q000032:analysis; D013131:Spine; D013977:Tibia
chemical_list: D000475:Alkenes; D004042:Dietary Fats, Unsaturated; D010938:Plant Oils; D003060:Cod Liver Oil