title: Trunk Muscle Size and Composition Assessment in Older Adults with Chronic Low Back Pain: An Intra-Examiner and Inter-Examiner Reliability Study.
abstract: To evaluate intra- and inter-examiner reliability for the assessment of relative cross-sectional area, muscle-to-fat infiltration indices, and relative muscle cross-sectional area, i.e., total cross-sectional area minus intramuscular fat, from T1-weighted magnetic resonance images obtained in older adults with chronic low back pain.
  
  
  
  Reliability study.
  
  
  
  n = 13 (69.3 ± 8.2 years old)
  
  
  
  After lumbar magnetic resonance imaging, two examiners produced relative cross-sectional area measurements of multifidi, erector spinae, psoas, and quadratus lumborum by tracing regions of interest just inside fascial borders. Pixel-intensity summaries were used to determine muscle-to-fat infiltration indices; relative muscle cross-sectional area was calculated. Intraclass correlation coefficients were used to estimate intra- and inter-examiner reliability; standard error of measurement was calculated.
  
  
  
  Intra-examiner intraclass correlation coefficient point estimates for relative cross-sectional area, muscle-to-fat infiltration indices, and relative muscle cross-sectional area were excellent for multifidi and erector spinae across levels L2-L5 (ICC = 0.77-0.99). At L3, intra-examiner reliability was excellent for relative cross-sectional area, muscle-to-fat infiltration indices, and relative muscle cross-sectional area for both psoas and quadratus lumborum (ICC = 0.81-0.99). Inter-examiner intraclass correlation coefficients ranged from poor to excellent for relative cross-sectional area, muscle-to-fat infiltration indices, and relative muscle cross-sectional area.
  
  
  
  Assessment of relative cross-sectional area, muscle-to-fat infiltration indices, and relative muscle cross-sectional area in older adults with chronic low back pain can be reliably determined by one examiner from T1-weighted images. Such assessments provide valuable information, as muscle-to-fat infiltration indices and relative muscle cross-sectional area indicate that a substantial amount of relative cross-sectional area may be magnetic resonance-visible intramuscular fat in older adults with chronic low back pain.
authors.affiliation: *Department of Physical Therapy, University of Delaware, Newark, Delaware, USA; megsions@udel.edu.
authors.forename: Jaclyn Megan
authors.initials: JM
authors.lastname: Sions
authors.affiliation: Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
authors.forename: Andrew Craig
authors.initials: AC
authors.lastname: Smith
authors.affiliation: *Department of Physical Therapy, University of Delaware, Newark, Delaware, USA;
authors.forename: Gregory Evan
authors.initials: GE
authors.lastname: Hicks
authors.affiliation: Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
authors.forename: James Matthew
authors.initials: JM
authors.lastname: Elliott
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging; D000368:Aged; D000369:Aged, 80 and over; D064131:Back Muscles / Q000000981:diagnostic imaging*; D001823:Body Composition; D059350:Chronic Pain / Q000473:pathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D017116:Low Back Pain / Q000473:pathology*; D008161:Lumbosacral Region / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results
keywords: Low Back Pain; Magnetic Resonance Imaging; Multifidi; Muscle;  Intramuscular Fat
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