title: Quantitative ultrasound imaging of Achilles tendon integrity in symptomatic and asymptomatic individuals: reliability and minimal detectable change.
abstract: BACKGROUND
  Quantifying the integrity of the Achilles tendon (AT) is a rehabilitation challenge. Adopting quantitative ultrasound measurements (QUS measurements) of the AT could fill this gap by 1) evaluating the test-retest reliability and accuracy of QUS measurements of the AT; 2) determining the best protocol for collecting QUS measurements in clinical practice.
  
  
  METHODS
  A total of 23 ATs with symptoms of Achilles tendinopathy and 63 asymptomatic ATs were evaluated. Eight images were recorded for each AT (2 visits × 2 evaluators × 2 images). Multiple sets of QUS measurements were taken: geometric (thickness, width, area), first-order statistics (computed from a grayscale histogram distribution: echogenicity, variance, skewness, kurtosis, entropy) and texture features (computed from co-occurrence matrices: contrast, energy, homogeneity). A generalizability study quantified the reliability and standard error of measurement (accuracy) of each QUS measurement, and a decision study identified the best measurement taking protocols.
  
  
  RESULTS
  Geometric QUS measurements demonstrated excellent accuracy and reliability. QUS measurements computed from the grayscale histogram distribution revealed poor accuracy and reliability. QUS measurements derived from co-occurrence matrices showed variable accuracy and moderate to excellent reliability. In clinical practice, using an average of the results of three images collected by a single evaluator during a single visit is recommended.
  
  
  CONCLUSIONS
  The use of geometric QUS measurements enables quantification of AT integrity in clinical practice and research settings. More studies on QUS measurements derived from co-occurrence matrices are warranted.
authors.affiliation: Pathokinesiology Laboratory, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR) - Institut de réadaptation Lindsay-Gingras de Montréal, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Centre-Sud-de-l'Île-de-Montréal, Montreal, Canada ; School of Rehabilitation, Université de Montréal, Pavillon 7077 Avenue du Parc, Station Centre-Ville, P.O. Box 6128, Montreal, Quebec H3C 3J7 Canada.
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Nadeau
authors.affiliation: Pathokinesiology Laboratory, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR) - Institut de réadaptation Lindsay-Gingras de Montréal, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Centre-Sud-de-l'Île-de-Montréal, Montreal, Canada ; Faculty of Medicine, Université de Montréal, Montreal, Canada.
authors.forename: Amélie
authors.initials: A
authors.lastname: Desrochers
authors.affiliation: Faculty of Medicine, Université de Montréal, Montreal, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Lamontagne
authors.affiliation: Pathokinesiology Laboratory, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR) - Institut de réadaptation Lindsay-Gingras de Montréal, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Centre-Sud-de-l'Île-de-Montréal, Montreal, Canada ; Occupational Health and Safety Research Institute Robert-Sauvé (IRSST), Montreal, Canada.
authors.forename: Christian
authors.initials: C
authors.lastname: Larivière
authors.affiliation: Pathokinesiology Laboratory, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR) - Institut de réadaptation Lindsay-Gingras de Montréal, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Centre-Sud-de-l'Île-de-Montréal, Montreal, Canada ; School of Rehabilitation, Université de Montréal, Pavillon 7077 Avenue du Parc, Station Centre-Ville, P.O. Box 6128, Montreal, Quebec H3C 3J7 Canada.
authors.forename: Dany H
authors.identifier: 0000-0003-3464-4667
authors.initials: DH
authors.lastname: Gagnon
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging* / Q000473:pathology; D016022:Case-Control Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D052256:Tendinopathy / Q000000981:diagnostic imaging* / Q000473:pathology; D014463:Ultrasonography / Q000379:methods
keywords: Achilles tendon; Computer-assisted image analysis; Measures; Musculoskeletal system; Quantitative evaluation; Rehabilitation; Reproducibility; Tendinopathy; Ultrasonography