title: Manual segmentation of individual muscles of the quadriceps femoris using MRI: a reappraisal.
abstract: OBJECTIVE
  To propose a manual segmentation method for individual quadriceps femoris (QF) muscles and to test its reliability for muscle volume estimation.
  
  
  METHODS
  Images were acquired every 5 mm along the thigh using a 3T MRI scanner on 10 young (mean age: 25 years) and 10 older (mean age: 75 years) adults using a three-point 3D Dixon sequence. In each slice, anatomical cross-sectional areas of the individual quadriceps muscles of the dominant leg were outlined by two operators working independently. Differences between operators were assessed by means of Bland-Altman plots and intraclass correlation coefficients (ICC). This study was approved by the local Ethics Committee.
  
  
  RESULTS
  Precise delimitation of individual muscles along the femur often remains challenging, particularly near their insertion areas where some muscles may be partially or totally fused. There was, however, an excellent interoperator segmentation reliability despite a systematic significant difference between operators (ICC > 0.99), mainly due to delineation divergences. Considering all subjects and muscles, differences between operators were all lower than 4.4%.
  
  
  CONCLUSIONS
  This work has demonstrated the excellent reliability of manual segmentation to assess cross-sectional areas and therefore the volume of individual QF muscles using MRI. It may serve as a basis for a future segmentation consensus of the QF muscles.
authors.affiliation: Institut de Myologie, UPMC UM 76, INSERM U 974, CNRS UMR 7215, GH Pitié-Salpêtrière, Paris, France.
authors.forename: Yoann
authors.initials: Y
authors.lastname: Barnouin
authors.forename: Gillian
authors.initials: G
authors.lastname: Butler-Browne
authors.forename: Thomas
authors.initials: T
authors.lastname: Voit
authors.forename: David
authors.initials: D
authors.lastname: Reversat
authors.forename: Noura
authors.initials: N
authors.lastname: Azzabou
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Leroux
authors.forename: Anthony
authors.initials: A
authors.lastname: Behin
authors.forename: Jamie S
authors.initials: JS
authors.lastname: McPhee
authors.forename: Pierre G
authors.initials: PG
authors.lastname: Carlier
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Hogrel
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology*; D000465:Algorithms; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology*; D015588:Observer Variation; D009929:Organ Size; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013848:Thigh / Q000033:anatomy & histology; D055815:Young Adult
keywords: anatomical cross-sectional area; muscle volume; nuclear magnetic resonance imaging; quadriceps femoris; reliability; segmentation