title: Quantitative Skeletal Muscle MRI: Part 2, MR Spectroscopy and T2 Relaxation Time Mapping-Comparison Between Boys With Duchenne Muscular Dystrophy and Healthy Boys.
abstract: OBJECTIVE
  The purpose of this study is to validate the use of MR spectroscopy (MRS) in measuring muscular fat and to compare it with T2 maps in differentiating boys with Duchenne muscular dystrophy (DMD) from healthy boys.
  
  
  METHODS
  Forty-two boys with DMD and 31 healthy boys were evaluated with MRI with (1)H-MRS and T2 maps. Grading of muscle fat and edema on conventional images, calculation of fat fractions ([fat / fat] + water) on MRS, and calculation of T2 fat values on T2 maps of the gluteus maximus and vastus lateralis muscles were performed. Group comparisons were made. The 95% reference interval (RI) of fat fraction for the control group was applied and compared with T2 map results.
  
  
  RESULTS
  Minimal fat on T1-weighted images was seen in 90.3% (gluteus maximus) and 71.0% (vastus lateralis) of healthy boys, versus 33.3% (gluteus maximus) and 52.4% (vastus lateralis) of boys with DMD. Muscle edema was seen in none of the healthy boys versus 52.4% (gluteus maximus) and 57.1% (vastus lateralis) of the boys with DMD. Fat fractions were higher in the DMD group (52.7%, gluteus maximus; 27.3%, vastus lateralis) than in the control group (12.8%, gluteus maximus; 13.7%, vastus lateralis) (p < 0.001). The 95% RI for gluteus maximus (38.7%) resulted in 61.9% sensitivity and 100% specificity for differentiating boys with DMD from healthy boys, whereas the value for vastus lateralis (17.8%) resulted in 76.2% sensitivity and 100% specificity; both had lower accuracy than did T2 maps (100% sensitivity and specificity). There was a positive correlation between T2 fat values and fat fractions (p < 0.0001).
  
  
  CONCLUSIONS
  In differentiation of the two groups, T2 maps were more accurate than MRS. Fat fractions can underestimate the actual amount of fat because of coexisting muscle edema in DMD.
authors.affiliation: 1 Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH 45229-3039.
authors.forename: Hee Kyung
authors.initials: HK
authors.lastname: Kim
authors.affiliation: 1 Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH 45229-3039.
authors.forename: Suraj
authors.initials: S
authors.lastname: Serai
authors.affiliation: 1 Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH 45229-3039.
authors.forename: Diana
authors.initials: D
authors.lastname: Lindquist
authors.affiliation: 1 Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH 45229-3039.
authors.forename: Arnold C
authors.initials: AC
authors.lastname: Merrow
authors.affiliation: 2 Department of Mathematical Sciences, University of Cincinnati, Cincinnati, OH.|3 Department of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Horn
authors.affiliation: 4 Department of Pharmacology, Korea University College of Medicine, Seoul, Republic of Korea.
authors.forename: Dong Hoon
authors.initials: DH
authors.lastname: Kim
authors.affiliation: 3 Department of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH.
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Wong
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology*; D020388:Muscular Dystrophy, Duchenne / Q000473:pathology*; D012680:Sensitivity and Specificity
keywords: Duchenne muscular dystrophy; MR spectroscopy; MRI; T2 relaxation time mapping; skeletal muscle