title: Regional intra-subject variability in abdominal adiposity limits usefulness of computed tomography.
abstract: OBJECTIVE
  Computed tomography (CT) and magnetic resonance imaging, the most accurate methods of abdominal fat measurement, have been applied using a number of protocols, ranging from single-slice area determination to multiple-slice volume calculation. The aim of this study was to assess the validity of single-slice CT for abdominal fat area measurement by estimating the intra-subject variability in abdominal fat areas and comparing the ranking of subjects across four contiguous abdominal levels.
  
  
  METHODS
  Nineteen premenopausal women (age, 35.3 +/- 1.4 years; mean +/- SE) were studied. CT was used to measure intra-abdominal fat (IAF) area, percentage of total intra-abdominal area (%IAF), subcutaneous abdominal fat (SAF) area, and IAF/SAF at four adjacent cross-sectional lumbar levels (L2-L4). Intra-subject variability (percentage) was defined as SD/mean x 100. Total body fat was measured by DXA, which was further analyzed for central abdominal fat.
  
  
  RESULTS
  Mean body mass index was 24.9 +/- 1.0 kg/m(2). The average (range) intra-subject variability was 28% (8% to 61%) for IAF, 46% (19% to 124%) for %IAF, 26% (14% to 38%) for SAF area, and 19% (7% to 71%) for IAF/SAF. The pattern of this variability was not uniform between subjects, because their ranking by IAF area was markedly different at each CT level.
  
  
  CONCLUSIONS
  We demonstrated significant intra-subject variability in CT-measured adipose tissue areas across four predetermined sites. This resulted in a difference in the ordering of subjects by IAF at each of the four imaging sites, suggesting that the usefulness of single-slice CT in the assessment of abdominal adiposity in premenopausal women may be limited, particularly when performed for the purpose of making comparisons between subjects based on abdominal fat area.
authors.affiliation: Diabetes and Metabolism Research Program, Garvan Institute of Medical Research, Darlinghurst, Sydney NSW 2010, Australia.
authors.forename: Jerry R
authors.initials: JR
authors.lastname: Greenfield
authors.forename: Katherine
authors.initials: K
authors.lastname: Samaras
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Chisholm
authors.forename: Lesley V
authors.initials: LV
authors.lastname: Campbell
mesh_terms: D000005:Abdomen; D000273:Adipose Tissue; D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D017697:Premenopause; D014057:Tomography, X-Ray Computed