title: A preliminary study using virtual touch imaging and quantification for the assessment of skin stiffness in systemic sclerosis.
abstract: OBJECTIVE
  To evaluate ultrasound Virtual Touch Imaging and Quantification (VTIQ) as a method for determining absolute skin stiffness in patients with systemic sclerosis (SSc).
  
  
  METHODS
  Skin thickness, assessed by the modified Rodnan Skin Score (mRSS) and absolute skin stiffness, using VTIQ, were measured at all mRSS anatomical sites to quantify the shear wave velocity (in m/s) in 26 SSc patients and in 17 age- and gender-matched controls. Correlations between mRSS and absolute skin stiffness, and comparisons between patients and controls were analysed statistically using Mann-Whitney U tests and correlations between variables using Pearson's. P values <0.05 were considered significant.
  
  
  RESULTS
  Shear wave velocity as a measure of skin stiffness was significantly higher in SSc than in controls in 11 out of 16 mRSS sites investigated. Shear-wave velocity was strongly correlated with the local mRSS in the following anatomical sites: forearm, hand, phalanx, and thigh. In the patient group, clinically unaffected skin could also be differentiated from healthy skin using shear-wave velocity.
  
  
  CONCLUSIONS
  VTIQ represents an innovative and promising technique that provides, for the first time, a non-invasive, absolute quantification of skin stiffness. Further studies of VTIQ are required, but this early study supports the clinical and scientific potential of this new measure of skin involvement in SSc.
authors.affiliation: Rheumatology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal. tlousasantiago@hotmail.com.
authors.forename: Tânia
authors.initials: T
authors.lastname: Santiago
authors.affiliation: Leeds Institute for Rheumatic and Musculoskeletal Medicine, University of Leeds; and NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds Teaching Hospital NHS Trust, Leeds, UK.
authors.forename: Begonya
authors.initials: B
authors.lastname: Alcacer-Pitarch
authors.affiliation: Rheumatology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Salvador
authors.affiliation: Leeds Institute for Rheumatic and Musculoskeletal Medicine, University of Leeds; and NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds Teaching Hospital NHS Trust, Leeds, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: Del Galdo
authors.affiliation: Leeds Institute for Rheumatic and Musculoskeletal Medicine, University of Leeds; and NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds Teaching Hospital NHS Trust, Leeds, UK.
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Redmond
authors.affiliation: Rheumatology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.
authors.forename: José António P
authors.initials: JA
authors.lastname: da Silva
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004548:Elasticity; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011379:Prognosis; D012595:Scleroderma, Systemic / Q000000981:diagnostic imaging* / Q000473:pathology; D012720:Severity of Illness Index; D012867:Skin / Q000000981:diagnostic imaging* / Q000473:pathology