title: Skeletal muscles of ambulant children with Duchenne muscular dystrophy: validation of multicenter study of evaluation with MR imaging and MR spectroscopy.
abstract: OBJECTIVE
  To validate a multicenter protocol that examines lower extremity skeletal muscles of children with Duchenne muscular dystrophy (DMD) by using magnetic resonance (MR) imaging and MR spectroscopy in terms of reproducibility of these measurements within and across centers.
  
  
  METHODS
  This HIPAA-compliant study was approved by the institutional review boards of all participating centers, and informed consent was obtained from each participant or a guardian. Standardized procedures with MR operator training and quality assurance assessments were implemented, and data were acquired at three centers by using different 3-T MR imaging instruments. Measures of maximal cross-sectional area (CSAmax), transverse relaxation time constant (T2), and lipid fraction were compared among centers in two-compartment coaxial phantoms and in two unaffected adult subjects who visited each center. Also, repeat MR measures were acquired twice on separate days in 30 boys with DMD (10 per center) and 10 unaffected boys. Coefficients of variation (CVs) were computed to examine the repeated-measure variabilities within and across centers.
  
  
  RESULTS
  CSAmax, T2 from MR imaging and MR spectroscopy, and lipid fraction were consistent across centers in the phantom (CV, <3%) and in the adult subjects who traveled to each site (CV, 2%-7%). High day-to-day reproducibility in MR measures was observed in boys with DMD (CSAmax, CV = 3.7% [25th percentile, 1.3%; 75th percentile, 5.1%]; contractile area, CV = 4.2% [25th percentile, 0.8%; 75th percentile, 4.9%]; MR imaging T2, CV = 3.1% [25th percentile, 1.2%; 75th percentile, 4.7%]; MR spectroscopy T2, CV = 3.9% [25th percentile, 1.5%; 75th percentile, 5.1%]; and lipid fraction, CV = 4.7% [25th percentile, 1.0%; 75th percentile, 5.3%]).
  
  
  CONCLUSIONS
  The MR protocol implemented in this multicenter study achieved highly reproducible measures of lower extremity muscles across centers and from day to day in ambulatory boys with DMD.
authors.affiliation: Department of Physical Therapy, Department of Physiology and Functional Genomics, and Department of Pediatrics and Molecular Genetics and Microbiology, Powell Gene Therapy Center, University of Florida, Box 100154, UFHSC, Gainesville, FL 32610; Advanced Imaging Research Center, Oregon Health and Science University, Portland, Ore; Division of Neurology and Department of Radiology, the Children's Hospital of Philadelphia, Philadelphia, Pa; Section of Integrative Biology, Division of Statistics and Scientific Computation, the University of Texas at Austin, Austin, Tex; Departments of Pediatrics and Neurology, Oregon Health and Science University, Shriners Hospital for Children, Portland, Ore; Nemours Children's Hospital, University of Central Florida College of Medicine, Orlando, Fla.
authors.forename: Sean C
authors.initials: SC
authors.lastname: Forbes
authors.forename: Glenn A
authors.initials: GA
authors.lastname: Walter
authors.forename: William D
authors.initials: WD
authors.lastname: Rooney
authors.forename: Dah-Jyuu
authors.initials: DJ
authors.lastname: Wang
authors.forename: Soren
authors.initials: S
authors.lastname: DeVos
authors.forename: Jim
authors.initials: J
authors.lastname: Pollaro
authors.forename: William
authors.initials: W
authors.lastname: Triplett
authors.forename: Donovan J
authors.initials: DJ
authors.lastname: Lott
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Willcocks
authors.forename: Claudia
authors.initials: C
authors.lastname: Senesac
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Daniels
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Byrne
authors.forename: Barry
authors.initials: B
authors.lastname: Russman
authors.forename: Richard S
authors.initials: RS
authors.lastname: Finkel
authors.forename: James S
authors.initials: JS
authors.lastname: Meyer
authors.forename: H Lee
authors.initials: HL
authors.lastname: Sweeney
authors.forename: Krista
authors.initials: K
authors.lastname: Vandenborne
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D006801:Humans; D008055:Lipids / Q000032:analysis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology*; D020388:Muscular Dystrophy, Duchenne / Q000378:metabolism* / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014481:United States
chemical_list: D015415:Biomarkers; D008055:Lipids