title: Chemical shift-based MRI to measure fat fractions in dystrophic skeletal muscle.
abstract: OBJECTIVE
  The relationship between fat fractions (FFs) determined based on multiple TE, unipolar gradient echo images and (1) H magnetic resonance spectroscopy (MRS) was evaluated using different models for fat-water decomposition, signal-to-noise ratios, and excitation flip angles.
  
  
  METHODS
  A combination of single-voxel proton spectroscopy ((1) H-MRS) and gradient echo imaging was used to determine muscle FFs in both normal and dystrophic muscles. In order to cover a large range of FFs, the soleus and vastus lateralis muscles of 22 unaffected control subjects, 16 subjects with collagen VI deficiency (COL6), and 71 subjects with Duchenne muscular dystrophy (DMD) were studied. (1) H-MRS-based FF were corrected for the increased muscle (1) H2 O T1 and T2 values observed in dystrophic muscles.
  
  
  RESULTS
  Excellent agreement was found between coregistered FFs derived from gradient echo images fit to a multipeak model with noise bias correction and the relaxation-corrected (1) H-MRS FFs (y = 0.93x + 0.003; R(2)  = 0.96) across the full range of FFs. Relaxation-corrected (1) H-MRS FFs and imaging-based FFs were significantly elevated (P < 0.01) in the muscles of COL6 and DMD subjects.
  
  
  CONCLUSIONS
  FFs, T2 , and T1 were all sensitive to muscle involvement in dystrophic muscle. MRI offered an additional advantage over single-voxel spectroscopy in that the tissue heterogeneity in FFs could be readily determined.
authors.affiliation: Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA.
authors.forename: William T
authors.initials: WT
authors.lastname: Triplett
authors.forename: Celine
authors.initials: C
authors.lastname: Baligand
authors.forename: Sean C
authors.initials: SC
authors.lastname: Forbes
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Willcocks
authors.forename: Donovan J
authors.initials: DJ
authors.lastname: Lott
authors.forename: Soren
authors.initials: S
authors.lastname: DeVos
authors.forename: Jim
authors.initials: J
authors.lastname: Pollaro
authors.forename: William D
authors.initials: WD
authors.lastname: Rooney
authors.forename: H Lee
authors.initials: HL
authors.lastname: Sweeney
authors.forename: Carsten G
authors.initials: CG
authors.lastname: Bönnemann
authors.forename: Dah-Jyuu
authors.initials: DJ
authors.lastname: Wang
authors.forename: Krista
authors.initials: K
authors.lastname: Vandenborne
authors.forename: Glenn A
authors.initials: GA
authors.lastname: Walter
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D024141:Collagen Type IV / Q000172:deficiency; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020388:Muscular Dystrophy, Duchenne / Q000473:pathology*; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio
chemical_list: D024141:Collagen Type IV
keywords: Duchenne muscular dystrophy; collagen VI; congenital muscular dystrophy; fat water imaging; magnetic resonance spectroscopy; muscle composition; skeletal muscle