title: Shear Wave Elastography May Be Superior to Greyscale Median for the Identification of Carotid Plaque Vulnerability: A Comparison with Histology.
abstract: OBJECTIVE
  There is a need to develop methods that reliably quantify characteristics associated with vulnerable carotid plaque. Greyscale median (GSM) and shear wave elastography (SWE) are two techniques that may improve individual plaque risk stratification. SWE, which quantifies Young's Modulus (YM) to estimate tissue stiffness, has been researched in the liver, breast, thyroid and prostate, but its use in carotid plaques is novel.
  
  
  METHODS
  The aim of this study was to quantify YM and GSM of plaques and compare to histology. 25 patients (64% male) with a mean age of 76 underwent both clinical and SWE imaging. The mean GSM was quantified over a cardiac cycle. The mean YM was quantified in multiple regions within the plaque over 5 frames. Histological features were assessed following carotid endarterectomy.
  
  
  RESULTS
  The mean YM of unstable plaques was significantly lower than that of stable plaques (50.0 kPa vs. 79.1 kPa; p = 0.027). The presence of intra-plaque hemorrhage, thrombus and increasing numbers of foam cells was also associated with a significantly lower YM. Plaque YM did not correlate well with plaque GSM (r =  .12). The mean plaque GSM was the same in both unstable and stable plaques. Fibrous plaques had a significantly higher GSM (p = 0.036).
  
  
  CONCLUSIONS
  In conclusion, SWE provides additional information on plaque stiffness which may be of clinical benefit to help identify vulnerable plaque, and warrants further study.
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, United Kingdom.
authors.forename: J W
authors.initials: JW
authors.lastname: Garrard
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Ummur
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, United Kingdom.
authors.forename: S
authors.initials: S
authors.lastname: Nduwayo
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, United Kingdom.
authors.forename: B
authors.initials: B
authors.lastname: Kanber
authors.affiliation: Department of Surgery, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom.
authors.forename: T C
authors.initials: TC
authors.lastname: Hartshorne
authors.affiliation: Department of Histopathology, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom.
authors.forename: K P
authors.initials: KP
authors.lastname: West
authors.affiliation: Department of Histopathology, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Moore
authors.affiliation: NIHR Biomedical Research Unit for Cardiovascular Sciences, University of Leicester, United Kingdom.
authors.forename: T G
authors.initials: TG
authors.lastname: Robinson
authors.affiliation: Department of Medical Physics, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom.
authors.forename: K V
authors.initials: KV
authors.lastname: Ramnarine
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000473:pathology; D004198:Disease Susceptibility; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D002546:Ischemic Attack, Transient / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012984:Software