title: Magnetic resonance imaging with k-means clustering objectively measures whole muscle volume compartments in sarcopenia/cancer cachexia.
abstract: OBJECTIVE
  Sarcopenia and cachexia are characterized by infiltration of non-contractile tissue within muscle which influences area and volume measurements. We applied a statistical clustering (k-means) technique to magnetic resonance (MR) images of the quadriceps of young and elderly healthy women and women with cancer to objectively separate the contractile and non-contractile tissue compartments.
  
  
  METHODS
  MR scans of the thigh were obtained for 34 women (n = 16 young, (median) age 26 y; n = 9 older, age 80 y; n = 9 upper gastrointestinal cancer patients, age 65 y). Segmented regions of consecutive axial images were used to calculate cross-sectional area and (gross) volume. The k-means unsupervised algorithm was subsequently applied to the MR binary mask image array data with resultant volumes compared between groups.
  
  
  RESULTS
  Older women and women with cancer had 37% and 48% less quadriceps muscle respectively than young women (p < 0.001). Application of k-means subtracted a significant 9%, 14% and 20% non-contractile tissue from the quadriceps of young, older and patient groups respectively (p < 0.001). There was a significant effect of group (i.e., cancer vs healthy) when controlling for age as a covariate (p = 0.003).
  
  
  CONCLUSIONS
  K-means objectively separates contractile and non-contractile tissue components. Women with upper GI cancer have significant fatty infiltration throughout whole muscle groups which is maintained when controlling for age.
authors: Wellcome Trust Clinical Research Facility, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK.
authors: Calum
authors: C
authors: Gray
authors: Thomas J
authors: TJ
authors: MacGillivray
authors: Clare
authors: C
authors: Eeley
authors: Nathan A
authors: NA
authors: Stephens
authors: Ian
authors: I
authors: Beggs
authors: Kenneth C
authors: KC
authors: Fearon
authors: Carolyn A
authors: CA
authors: Greig
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001825:Body Fluid Compartments / Q000378:metabolism*; D002100:Cachexia / Q000378:metabolism*; D016000:Cluster Analysis; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009119:Muscle Contraction; D052097:Quadriceps Muscle / Q000503:physiopathology*; D055948:Sarcopenia / Q000378:metabolism*; D055815:Young Adult