title: Reliability of ultrasound elastography for the quantification of transversus abdominis elasticity.
abstract: BACKGROUND
  The transversus abdominis (TrA), which is considered to be involved in controlling spinal stability, is covered by two muscles (i.e. the external and internal oblique muscles) as well as subcutaneous fat. Therefore, there were doubts about whether it was possible to perform highly reliable measurements of muscle elasticity.
  
  
  OBJECTIVE
  To investigate the reliability of ultrasound elastography for the quantification of elasticity of the TrA.
  
  
  METHODS
  A skilled and an unskilled operator of ultrasound elastography measured TrA elasticity in 10 healthy men (age, 24 ± 4 years; height, 172.0 ± 5.2 cm; weight, 72.3 ± 12.0 kg) in the supine position. The tests were repeated six times; of the six measured values, a group of four measurements showing the lowest coefficient of variation (CV) was adopted and the mean values were used for further analysis. This procedure was repeated twice on each participant on two different days.
  
  
  RESULTS
  The intra-class correlation coefficients (ICCs) between days for skilled and unskilled operators were 0.86 (P < 0.00) and 0.59 (P = 0.02), respectively, and the CVs were 8.7% and 13.8%, respectively. The ICCs between operators and CVs were in the range of 0.56-0.57 (P = 0.02-0.03) and 13.5-15.5%, respectively. No systematic error was found for any comparison.
  
  
  CONCLUSIONS
  The reliabilities of the skilled and unskilled operators were high and moderate, respectively.
authors.affiliation: Faculty of Sport Sciences, Waseda University, Japan.
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Hirayama
authors.affiliation: College of System Engineering and Science, Shibaura Institute of Technology, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Akagi
authors.affiliation: Department of Sports Science, Japan Institute of Sports Sciences, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takahashi
keywords: Shear wave; coefficient of variation; inter-class correlation; shear modulus