title: Estimation of Skeletal Muscle Mass and Visceral Adipose Tissue Volume by a Single Magnetic Resonance Imaging Slice in Healthy Elderly Adults.
abstract: BACKGROUND
  Assessing skeletal muscle (SM) and visceral adipose tissue (VAT) by a single MRI slice at lumbar vertebra (L) 3 can replace whole-body MRI in young and middle-aged adults. However, this technique has not been proven in older adults.
  
  
  OBJECTIVE
  The aim of this analysis was to reinvestigate the best estimate for SM and VAT in an independent population of healthy elderly people.
  
  
  METHODS
  SM and VAT were assessed by whole-body MRI in 84 subjects ≥60 y [45 men; mean ± SD age: 68.4 ± 5.4 y, mean ± SD body mass index (in kg/m2): 25.5 ± 3.5]. SM and VAT areas of 9 slices at the lumbar spine were analyzed. The best estimate was investigated by Pearson correlations. Total volumes (in liters) were predicted by the area at lumbar vertebra 3 (AL3). Besides Bland-Altman analysis, linear regressions were performed to explain the variance of the bias by age, height, and percentage of fat mass (%FM). In a mixed population (healthy elderly plus reference population), linear regression with total SM and VAT volume as dependent variables and AL3, age, and height as independent variables was applied.
  
  
  RESULTS
  When comparing the correlation coefficients between the tissue areas and total volumes, L3 was identified as the best estimate (r range: 0.71-0.94; all P < 0.05). However, Bland-Altman analysis showed a positive SM bias in men (mean ± SD: -1.0% ± 9.0%; P < 0.05) and a negative SM bias in women (mean ± SD: 3.7% ± 9.6%; P < 0.05). Contrary to SM, no significant bias was observed for VAT. In the elderly, stepwise linear regression showed height as a predictor for SM bias (R2= 0.21, SEE = 2.07 L; P < 0.05) and %FM and age as predictors of the nonsignificant VAT bias (R2= 0.26, SEE = 0.22L, P < 0.05), in men only. In the mixed population, AL3and height were predictors for total SM, and AL3for total VAT, independent of sex.
  
  
  CONCLUSIONS
  AL3was confirmed as the best estimate for SM and VAT volumes in healthy elderly adults. Contrary to VAT, there is a bias for SM, and height has to be added to the algorithm.
authors: Institute of Human Nutrition, Christian-Albrechts-University, Kiel, Germany.
authors: Lisa
authors: L
authors: Schweitzer
authors: Institute of Human Nutrition, Christian-Albrechts-University, Kiel, Germany.
authors: Corinna
authors: C
authors: Geisler
authors: Institute of Human Nutrition, Christian-Albrechts-University, Kiel, Germany.
authors: Maryam
authors: M
authors: Pourhassan
authors: Institute of Human Nutrition, Christian-Albrechts-University, Kiel, Germany.
authors: Wiebke
authors: W
authors: Braun
authors: Clinic for Diagnostic Radiology, Section of Biomedical Imaging, Molecular Imaging North Competence Center CC (MOIN CC), University Medical Center Schleswig-Holstein, Kiel, Germany; and.
authors: Claus-Christian
authors: CC
authors: Glüer
authors: Institute of Human Nutrition, Christian-Albrechts-University, Kiel, Germany; Institute of Nutritional Medicine, University of Hohenheim, Stuttgart, Germany.
authors: Anja
authors: A
authors: Bosy-Westphal
authors: Institute of Human Nutrition, Christian-Albrechts-University, Kiel, Germany; mmueller@nutrfoodsc.uni-kiel.de.
authors: Manfred J
authors: MJ
authors: Müller
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D050152:Intra-Abdominal Fat / Q000000981:diagnostic imaging*; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*
keywords: advanced age; age-related changes in body composition; assessment of body composition; imaging techniques; sarcopenia; sarcopenic obesity; simplification of the MRI protocol; skeletal muscle; visceral adipose tissue