title: Elastic Characteristics of the Normal Achilles Tendon Assessed by Virtual Touch Imaging Quantification Shear Wave Elastography.
abstract: OBJECTIVE
  To assess the elastic properties of the normal Achilles tendon in different age groups by Virtual Touch imaging quantification (VTIQ; Siemens Medical Solutions, Malvern, PA) shear wave elastography.
  
  
  METHODS
  A total of 326 healthy volunteers older than 18 years were divided into different groups by sex and age. The thickness, shear wave velocity (SWV) in sagittal and axial sections, and anisotropic coefficient of the Achilles tendon in a state of relaxation were obtained by conventional sonography and Virtual Touch imaging quantification elastography. These parameters were compared in different age and sex groups, and their correlations with age were evaluated.
  
  
  RESULTS
  The thickness of the Achilles tendon in men and women increased gradually with age, and it was larger in men than in women in each age group (P < .05). The SWV of the tendon in the sagittal section decreased slightly with age, but the sagittal and axial SWVs and anisotropic coefficient had no significant differences among different age groups (P > .05), and they also had no significant differences between men and women within any group (P > .05). The SWVs in the sagittal and axial sections and anisotropic coefficient had no correlation with age. Intraclass correlation coefficients for sagittal and axial SWVs obtained by 2 independent observers were 0.923 and 0.870, respectively.
  
  
  CONCLUSIONS
  The thickness of the Achilles tendon increased gradually with age. We confirmed that tendinous elastographic anisotropy and the stiffness of the tendon had no significant correlation with age.
authors.affiliation: Department of Ultrasound, Peking University Third Hospital, Beijing, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Fu
authors.affiliation: Department of Ultrasound, Peking University Third Hospital, Beijing, China cuijuegang@126.com.
authors.forename: Ligang
authors.initials: L
authors.lastname: Cui
authors.affiliation: Second Hospital of Beijing, Beijing, China.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: He
authors.affiliation: Department of Ultrasound, Peking University Third Hospital, Beijing, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Sun
mesh_terms: D000125:Achilles Tendon / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012737:Sex Factors; D014110:Touch; D055815:Young Adult
keywords: Achilles tendon; elasticity; elastography; musculoskeletal ultrasound; shear wave velocity