title: Shear Wave Elastography--A New Quantitative Assessment of Post-Irradiation Neck Fibrosis.
abstract: OBJECTIVE
  Shear wave elastography (SWE) is a new technique which provides quantitative assessment of soft tissue stiffness. The aim of this study was to assess the reliability of SWE stiffness measurements and its usefulness in evaluating post-irradiation neck fibrosis.
  
  
  METHODS
  50 subjects (25 patients with previous radiotherapy to the neck and 25 sex and age-matched controls) were recruited for comparison of SWE stiffness measurements (Aixplorer, Supersonic Imagine). 30 subjects (16 healthy individuals and 14 post-irradiated patients) were recruited for a reliability study of SWE stiffness measurements. SWE stiffness measurements of the sternocleidomastoid muscle and the overlying subcutaneous tissues of the neck were made. The cross-sectional area and thickness of the sternocleidomastoid muscle and the overlying subcutaneous tissue thickness of the neck were also measured. The post-irradiation duration of the patients was recorded.
  
  
  RESULTS
  The intraclass correlation coefficients for the intraoperator and interoperator reliability of deep and subcutaneous tissue SWE stiffness ranged from 0.90-0.99 and 0.77-0.94, respectively. The SWE stiffness measurements (mean +/- SD) of deep and subcutaneous tissues were significantly higher in the post-irradiated patients (64.6 ± 46.8 kPa and 63.9 ± 53.1 kPa, respectively) than the sex and age-matched controls (19.9 ± 7.8 kPa and 15.3 ± 8.37 respectively) (p < 0.001). The SWE stiffness increased with increasing post-irradiation therapy duration in the Kruskal Wallis test (p < 0.001) and correlated with muscle atrophy and subcutaneous tissue thinning (p < 0.01).
  
  
  CONCLUSIONS
  SWE is a reliable technique and may potentially be an objective and specific tool in quantifying deep and subcutaneous tissue stiffness, which in turn reflects the severity of neck fibrosis.
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong.
authors.forename: K H
authors.initials: KH
authors.lastname: Liu
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong.
authors.forename: K
authors.initials: K
authors.lastname: Bhatia
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong.
authors.forename: W
authors.initials: W
authors.lastname: Chu
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong.
authors.forename: L T
authors.initials: LT
authors.lastname: He
authors.affiliation: Department of Clinical Oncology, The Chinese University of Hong Kong, Hong Kong.
authors.forename: S F
authors.initials: SF
authors.lastname: Leung
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong.
authors.forename: A T
authors.initials: AT
authors.lastname: Ahuja
mesh_terms: D004210:Dissection; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005355:Fibrosis; D006801:Humans; D009333:Neck / Q000473:pathology / Q000528:radiation effects*; D011832:Radiation Injuries / Q000000981:diagnostic imaging* / Q000473:pathology; D018084:Ultrasonography, Interventional / Q000379:methods