title: Quantitative Dixon MRI sequences to relate muscle atrophy and fatty degeneration with range of motion and muscle force in brachial plexus injury.
abstract: Assessment of muscle atrophy and fatty degeneration in brachial plexus injury (BPI) could yield valuable insight into pathophysiology and could be used to predict clinical outcome. The objective of this study was to quantify and relate fat percentage and cross-sectional area (CSA) of the biceps to range of motion and muscle force of traumatic brachial plexus injury (BPI) patients.
  
  
  
  T1-weighted TSE sequence and three-point Dixon images of the affected and non-affected biceps brachii were acquired on a 3 Tesla magnetic resonance scanner to determine the fat percentage, total and contractile CSA of 20 adult BPI patients. Regions of interest were drawn by two independent investigators to determine the inter-observer reliability. Paired Students' t-test and multivariate analysis were used to relate fat percentage, total and contractile CSA to active flexion and biceps muscle force.
  
  
  
  The mean fat percentage 12±5.1% of affected biceps was higher than 6±1.0% of the non-affected biceps (p<0.001). The mean contractile CSA 8.1±5.1cm2of the affected biceps was lower than 19.4±4.9cm2of the non-affected biceps (p<0.001). The inter-observer reliability was excellent (ICC 0.82 to 0.96). The contractile CSA contributed most to the reduction in active flexion and muscle force.
  
  
  
  Quantitative measurement of fat percentage, total and contractile CSA using three-point Dixon sequences provides an excellent reliability and relates with active flexion and muscle force in BPI.
authors.affiliation: Department of Orthopaedics, Leiden University Medical Center, The Netherlands. Electronic address: b.j.duijnisveld@lumc.nl.
authors.forename: Bouke J
authors.initials: BJ
authors.lastname: Duijnisveld
authors.affiliation: Department of Orthopaedics, Leiden University Medical Center, The Netherlands.
authors.forename: Jan Ferdinand
authors.initials: JF
authors.lastname: Henseler
authors.affiliation: Department of Radiology, Leiden University Medical Center, The Netherlands.
authors.forename: Monique
authors.initials: M
authors.lastname: Reijnierse
authors.affiliation: Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, The Netherlands; Mathematica institute Leiden University, Leiden University Medical Center, The Netherlands.
authors.forename: Marta
authors.initials: M
authors.lastname: Fiocco
authors.affiliation: C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, The Netherlands.
authors.forename: Hermien E
authors.initials: HE
authors.lastname: Kan
authors.affiliation: Department of Orthopaedics, Leiden University Medical Center, The Netherlands.
authors.forename: Rob G H H
authors.initials: RG
authors.lastname: Nelissen
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging* / Q000473:pathology; D000328:Adult; D001917:Brachial Plexus / Q000000981:diagnostic imaging / Q000293:injuries* / Q000503:physiopathology; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000503:physiopathology; D009133:Muscular Atrophy / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results
keywords: Brachial plexus injury; Fatty degeneration; Magnetic resonance imaging; Muscle atrophy; Muscle force; Range of motion