title: Shear wave elastography imaging of carotid plaques: feasible, reproducible and of clinical potential.
abstract: BACKGROUND
  Shear Wave Elastography (SWE) imaging is a novel ultrasound technique for quantifying tissue elasticity. Studies have demonstrated that SWE is able to differentiate between diseased and normal tissue in a wide range clinical applications. However its applicability to atherosclerotic carotid disease has not been established. The aim of this study was to assess the feasibility and potential clinical benefit of using SWE imaging for the assessment of carotid plaques.
  
  
  METHODS
  Eighty-one patients (mean age 76 years, 51 male) underwent greyscale and SWE imaging. Elasticity was quantified by measuring mean Young's Modulus (YM) within the plaque and within the vessel wall. Echogenicity was assessed using the Gray-Weale classification scale and the greyscale median (GSM).
  
  
  RESULTS
  Fifty four plaques with stenosis greater than 30% were assessed. Reproducibility of YM measurements, quantified by the inter-frame coefficient of variation, was 22% within the vessel wall and 19% within the carotid plaque. Correlation with percentage stenosis was significant for plaque YM (p = 0.003), but insignificant for plaque GSM (p = 0.46). Plaques associated with focal neurological symptoms had significantly lower mean YM than plaques in asymptomatic patients (62 kPa vs 88 kPa; p = 0.01). Logistic regression and Receiver Operating Characteristic (ROC) analysis showed improvements in sensitivity and specificity when percentage stenosis was combined with the YM (area under ROC = 0.78).
  
  
  CONCLUSIONS
  Our study showed SWE is able to quantify carotid plaque elasticity and provide additional information that may be of clinical benefit to help identify the unstable carotid plaque.
authors.affiliation: Department of Medical Physics, University Hospitals of Leicester NHS Trust, Sandringham Building, Level 1, Leicester Royal Infirmary, Infirmary Square, Leicester LE1 5WW UK. kumar.ramnarine@uhl-tr.nhs.uk.
authors.forename: Kumar V
authors.initials: KV
authors.lastname: Ramnarine
authors.forename: James W
authors.initials: JW
authors.lastname: Garrard
authors.forename: Baris
authors.initials: B
authors.lastname: Kanber
authors.forename: Sarah
authors.initials: S
authors.lastname: Nduwayo
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Hartshorne
authors.forename: Thompson G
authors.initials: TG
authors.lastname: Robinson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059168:Carotid Intima-Media Thickness; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D004452:Echocardiography / Q000379:methods*; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D033081:Shear Strength; D013314:Stress, Mechanical