title: Characterization of complicated carotid plaque with magnetic resonance direct thrombus imaging in patients with cerebral ischemia.
abstract: BACKGROUND
  Thromboembolic disease secondary to complicated carotid atherosclerotic plaque is a major cause of cerebral ischemia. Clinical management relies on the detection of significant (>70%) carotid stenosis. A large proportion of patients suffer irreversible cerebral ischemia as a result of lesser degrees of stenosis. Diagnostic techniques that can identify nonstenotic high-risk plaque would therefore be beneficial. High-risk plaque is defined histologically if it contains hemorrhage/thrombus. Magnetic resonance direct thrombus imaging (MRDTI) is capable of detecting methemoglobin within intraplaque hemorrhage. We assessed this as a marker of complicated plaque and compared its accuracy with histological examination of surgical endarterectomy specimens.
  
  
  RESULTS
  Sixty-three patients underwent successful MRDTI and endarterectomy with histological examination. Of these, 44 were histologically defined as complicated (type VI plaque). MRDTI demonstrated 3 false-positive and 7 false-negative results, giving a sensitivity and specificity of 84%, negative predictive value of 70%, and positive predictive value of 93%. The interobserver (kappa=0.75) and intraobserver (kappa=0.9) agreement for reading MRDTI scans was good.
  
  
  CONCLUSIONS
  MRDTI of the carotid vessels in patients with cerebral ischemia is an accurate means of identifying histologically confirmed complicated plaque. The high contrast generated by short T1 species within the plaque allows for ease of interpretation, making this technique highly applicable in the research and clinical setting for the investigation of carotid atherosclerotic disease.
authors.affiliation: Department of Academic Radiology, Medical School, University Hospital, Nottingham, UK. alan.moody@sw.ca
authors.forename: Alan R
authors.initials: AR
authors.lastname: Moody
authors.forename: Rachael E
authors.initials: RE
authors.lastname: Murphy
authors.forename: Paul S
authors.initials: PS
authors.lastname: Morgan
authors.forename: Anne L
authors.initials: AL
authors.lastname: Martel
authors.forename: G S
authors.initials: GS
authors.lastname: Delay
authors.forename: Steve
authors.initials: S
authors.lastname: Allder
authors.forename: Shane T
authors.initials: ST
authors.lastname: MacSweeney
authors.forename: William G
authors.initials: WG
authors.lastname: Tennant
authors.forename: John
authors.initials: J
authors.lastname: Gladman
authors.forename: John
authors.initials: J
authors.lastname: Lowe
authors.forename: Beverley J
authors.initials: BJ
authors.lastname: Hunt
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000209:etiology; D002341:Carotid Artery Thrombosis / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D016893:Carotid Stenosis / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D004691:Endarterectomy; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity