title: Hyperdense internal carotid artery sign: a CT sign of acute ischemia.
abstract: OBJECTIVE
  The hyperdense middle cerebral artery sign (HMCAS) is a well-established marker of early ischemia on noncontrast computed tomography of the brain (NCCT). Recently the MCA dot sign has been described and proposed to indicate thrombosis of the M2 or M3 middle cerebral artery branches. The purpose of this study was to define the hyperdense ICA sign (HICAS) and determine its prevalence, diagnostic and prognostic value, and its reliability as a marker for ischemia.
  
  
  METHODS
  Noncontrast computed tomography scans of 71 patients with acute ischemic stroke were analyzed for the presence of a HICAS, HMCAS, or MCA dot sign. For the validation of HICA and HMCA signs on NCCT, 32 of 71 patients who underwent gold standard CT angiography (CTA) before thrombolytic therapy were included in the analysis. The presence of a HICAS was correlated with initial neurological severity and the short and long-term outcomes.
  
  
  RESULTS
  A HICAS was found in 24% of patients on NCCT. In patients with a HICAS, mean age was 63+/-17.4 and mean time from symptom onset to CT was 103 minutes. Interobserver agreement was excellent for the HICAS. The HICAS has high specificity (100%) and positive predictive value (100%) in predicting the presence of distal internal carotid artery thrombus on CTA. Patients with a HICAS had a more severe initial neurological deficit and worse prognosis than patients without a HICAS.
  
  
  CONCLUSIONS
  The HICAS is a reliable and a highly specific marker of thromboembolic occlusion of the distal ICA and is associated with severe initial neurological deficit and worse outcome despite thrombolytic therapy.
authors.affiliation: Department of Clinical Neurological Sciences, University of Western Ontario, London Health Sciences, University Campus, London, Ontario, Canada. ozcan_99@yahoo.com
authors.forename: Ozcan
authors.initials: O
authors.lastname: Ozdemir
authors.forename: Andrew
authors.initials: A
authors.lastname: Leung
authors.forename: Miguel
authors.initials: M
authors.lastname: Bussiére
authors.forename: Vladimir
authors.initials: V
authors.lastname: Hachinski
authors.forename: David
authors.initials: D
authors.lastname: Pelz
mesh_terms: D000368:Aged; D001921:Brain / Q000473:pathology*; D002545:Brain Ischemia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging* / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011871:Radiology / Q000379:methods; D012307:Risk Factors; D020521:Stroke / Q000000981:diagnostic imaging / Q000473:pathology; D015912:Thrombolytic Therapy / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome