title: Reproducibility of ultrasound and magnetic resonance imaging measurements of tendon size.
abstract: OBJECTIVE
  To investigate the intra- and inter-tester reproducibility of measurements of the Achilles tendon, tibialis anterior tendon, and the tibialis posterior tendon in football players using ultrasound (US) and magnetic resonance imaging (MRI).
  
  
  METHODS
  Eleven asymptomatic football players were examined. Using a standardized US scanning protocol, the tendons were examined by two observers with US for thickness, width, and cross-sectional area. One observer conducted the procedure twice. The subjects also underwent an MRI examination, and the assessment of tendon size was conducted twice by two observers.
  
  
  RESULTS
  The best reproducibility judged by coefficient of variation (CV) and 95% confidence interval was determined for the Achilles tendon on both US and MRI. The variability of US on measurements on the tibialis anterior and tibialis posterior tendons was less than that when using MRI. In 12 out of 18 measurements, there were systematic differences between observers as judged by one-sided F-test.
  
  
  CONCLUSIONS
  The reproducibility of the three tendons was limited. Precaution should be taken when looking for minor quantitative changes, i.e., training-induced hypertrophy, and when doing so, the Achilles tendon should be used.
authors.affiliation: Department of Radiology, Section of Ultrasound, Rigshospitalet, Copenhagen, Denmark. brushoj@dadlnet.dk
authors.forename: C
authors.initials: C
authors.lastname: Brushøj
authors.forename: B M
authors.initials: BM
authors.lastname: Henriksen
authors.forename: E
authors.initials: E
authors.lastname: Albrecht-Beste
authors.forename: P
authors.initials: P
authors.lastname: Hölmich
authors.forename: K
authors.initials: K
authors.lastname: Larsen
authors.forename: M
authors.initials: M
authors.lastname: Bachmann Nielsen
mesh_terms: D000125:Achilles Tendon / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D000843:Ankle Joint; D005538:Football; D006801:Humans; D008279:Magnetic Resonance Imaging; D015588:Observer Variation; D009929:Organ Size; D015203:Reproducibility of Results; D013710:Tendons / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D014463:Ultrasonography