title: Identification of patients with a histologically unstable carotid plaque using ultrasonic plaque image analysis.
abstract: OBJECTIVE
  In patients with carotid stenosis the risk of stroke is highest in the first few days after onset of symptoms and it is low in asymptomatic patients. The ability to identify patients with a high (or low) probability of having a histologically unstable plaque might become a complimentary method that can refine the indications for surgical intervention.
  
  
  METHODS
  Two histopathologists, using validated American Heart Association criteria, independently graded plaques harvested during carotid endarterectomy. Preoperative Duplex images were independently assessed for juxtaluminal black area, plaque type, plaque area, and grey-scale median (GSM) following image normalization. Logistic regression analysis was then performed to create a model for predicting predominantly histologically unstable or stable plaques.
  
  
  RESULTS
  A total of 126 patients were included in the study. Based on the presence and extent of histological features including haemorrhage, thrombus, fibrous tissue, lipid core, inflammation, neovascularity, foam cells, and cap rupture, 39 plaques were graded as predominantly stable, while 87 were predominantly unstable. Unstable plaques were associated with a plaque area >95 mm(2) (OR 4.15; 95% CI 1.34-12.8 p = .009), a juxtaluminal black area >6 mm(2) (OR 2.77; 95% CI 1.24 to 6.17 p = .01) and a GSM <25 (OR 3.76; 95% CI 1.14-12.39). Logistic regression indicated that patients with the first two features had a 90% probability of having a histologically unstable plaque. The model was used to calculate the probability of having an unstable plaque in each patient. The receiver operating characteristic curve using the p value was 0.68 (95% CI 0.59-0.78).
  
  
  CONCLUSIONS
  Computerized plaque analysis has the potential to identify patients with histologically unstable carotid plaques. This model requires validation, but offers the potential to influence patient selection for emergency interventions and the monitoring of medical therapy.
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Leicester, UK. Electronic address: ms447@le.ac.uk.
authors.forename: M K
authors.initials: MK
authors.lastname: Salem
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; NIHR Leicester Cardiovascular Biomedical Research Unit, Leicester, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Bown
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.
authors.forename: R D
authors.initials: RD
authors.lastname: Sayers
authors.affiliation: Department of Histopathology, University Hospitals Leicester, Leicester, UK.
authors.forename: K
authors.initials: K
authors.lastname: West
authors.affiliation: Department of Histopathology, University Hospitals Leicester, Leicester, UK.
authors.forename: D
authors.initials: D
authors.lastname: Moore
authors.affiliation: Department of Surgery, St George's University of London, London, UK; University of Nicosia Medical School, Nicosia, Cyprus.
authors.forename: A
authors.initials: A
authors.lastname: Nicolaides
authors.affiliation: NIHR Leicester Cardiovascular Biomedical Research Unit, Leicester, UK.
authors.forename: T G
authors.initials: TG
authors.lastname: Robinson
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.
authors.forename: A R
authors.initials: AR
authors.lastname: Naylor
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D002339:Carotid Arteries / Q000000981:diagnostic imaging* / Q000601:surgery; D002340:Carotid Artery Diseases / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D018450:Disease Progression; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D058226:Plaque, Atherosclerotic; D011237:Predictive Value of Tests; D012372:ROC Curve; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D020521:Stroke / Q000209:etiology; D018616:Ultrasonography, Doppler, Duplex
keywords: Atherosclerosis; Carotid; Plaque instability; Ultrasound