title: The hyperdense posterior cerebral artery sign: a computed tomography marker of acute ischemia in the posterior cerebral artery territory.
abstract: OBJECTIVE
  In the anterior circulation, the hyperdense middle cerebral artery (MCA) sign is a well-established marker for early ischemia. Similarly, the hyperdense basilar artery sign or the MCA "dot" sign may be a diagnostic clue for basilar artery or distal MCA branch thrombosis. The purpose of this study was to define the hyperdense posterior cerebral artery (PCA) sign and determine its incidence, diagnostic value, and reliability as a marker for ischemia in the territory of the PCA.
  
  
  METHODS
  Cranial computed tomographies (CCTs) of 48 patients with proven acute ischemia (<12 hours) in the PCA territory were compared by 3 independent and blinded readers to the CCTs of 86 age-matched patients without PCA infarction. Using follow-up imaging, the correlation of the hyperdense PCA (HPCA) with infarct size, thalamic infarction, and bleeding were investigated.
  
  
  RESULTS
  An HPCA was found in 35.4% of all patients with PCA infarction, typically within the ambient cistern, with a specificity of 95.4%. The thalamus was affected significantly more often (P=0.009) and the size of the infarct was significantly more often large than medium (P=0.018) or small (P<0.001) when an HPCA was present. Hemorrhagic transformation tended to occur more often when the HPCA was present.
  
  
  CONCLUSIONS
  An HPCA was detected in more than one third of all patients with PCA ischemia, suiting the incidence of the hyperdense MCA. Based on our results, this sign may not only be helpful in the early diagnosis of PCA infarction but might also act as a prognostic marker in acute PCA territory ischemic stroke.
authors.affiliation: Department of Neuroradiology, RWTH Aachen University, Aachen, Germany. tkrings@izkf.rwth-aachen.de
authors.forename: Timo
authors.initials: T
authors.lastname: Krings
authors.forename: Dagmar
authors.initials: D
authors.lastname: Noelchen
authors.forename: Michael
authors.initials: M
authors.lastname: Mull
authors.forename: Klaus
authors.initials: K
authors.lastname: Willmes
authors.forename: Ingo G
authors.initials: IG
authors.lastname: Meister
authors.forename: Peter
authors.initials: P
authors.lastname: Reinacher
authors.forename: Rudolf
authors.initials: R
authors.lastname: Toepper
authors.forename: Armin K
authors.initials: AK
authors.lastname: Thron
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology; D002545:Brain Ischemia / Q000175:diagnosis* / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D020762:Infarction, Posterior Cerebral Artery / Q000175:diagnosis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D020769:Posterior Cerebral Artery / Q000000981:diagnostic imaging* / Q000473:pathology*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*