title: In vivo measurements of human neck skin elasticity using MRI and finite element modeling.
abstract: OBJECTIVE
  The assessment of mechanical properties of the human skin is very important in investigating the mechanism of obstructive sleep apnea, a common disorder characterized by repetitive collapse and obstruction of the upper airway during sleep. In this study, a unique method, combining magnetic resonance imaging (MRI) and finite element modeling (FEM), was developed to obtain the value of the in vivo elastic modulus of the neck skin.
  
  
  METHODS
  A total of 22 subjects, 16 males and six females, were recruited to participate in the MRI studies. The changes in the airway and the neck size resulting from fluid shift from the lower body to the neck were measured based on the MR images. A two-dimensional plane strain FE model was built to simulate such changes in the neck cross-section for each subject.
  
  
  RESULTS
  Solving an inverse problem using FEM by matching the measured data, we obtained the in vivo elastic modulus of the neck skin to be 1.78 ± 1.73 MPa. Results showed that the elastic modulus tended to increase with age and body mass index for these subjects. A sensitivity analysis of the muscle and fat mechanical parameters was also performed to test their effects on the predicted skin elasticity.
  
  
  CONCLUSIONS
  The unique method developed in this study for measuring the in vivo elastic modulus of the neck skin is quite effective, and the skin elasticity value obtained using this method is credible.
authors.affiliation: School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.|Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
authors.forename: Yunqiang
authors.initials: Y
authors.lastname: An
authors.affiliation: School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.|Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
authors.forename: Changjin
authors.initials: C
authors.lastname: Ji
authors.affiliation: School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.|Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.|Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
authors.forename: Jianxia
authors.initials: J
authors.lastname: Wang
authors.affiliation: School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.|Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
authors.forename: Xinyue
authors.initials: X
authors.lastname: Zhang
authors.affiliation: School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.|Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
authors.forename: Yaqi
authors.initials: Y
authors.lastname: Huang
mesh_terms: D000328:Adult; D055119:Elastic Modulus; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009333:Neck; D012867:Skin / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: finite element modeling; fluid shift; in vivo elastic modulus; neck MRI; neck skin