title: The hyperdense vessel sign on CT predicts successful recanalization with the Merci device in acute ischemic stroke.
abstract: BACKGROUND
  The success of mechanical clot retrieval for acute ischemic stroke may be influenced by the characteristics of the occlusive thrombus. The thrombus can be partly characterized by CT, as the hyperdense vessel sign (HVS) suggests erythrocyte-rich clot whereas fibrin-rich clot may be isodense. We hypothesized that the physical clot characteristics that determine CT density may also determine likelihood of retrieval with the Merci device.
  
  
  METHODS
  We reviewed all acute stroke cases initially imaged with non-contrast CT before attempted Merci clot retrieval at a single center between 2004 and 2010. Each CT was blindly assessed for the presence or absence of the HVS, and post-retrieval angiograms were blindly assessed for reperfusion using the TICI scale.
  
  
  RESULTS
  Of 67 patients analyzed (mean age 69; median NIHSS 19; 61% female), the HVS was seen in 42, and no HVS was present in 25. Successful recanalization was achieved in 79% of patients with the HVS (33/42), but in only 36% (9/25) of patients without HVS (p=0.001). The HVS was the only significant predictor of recanalization while accounting for age, treatment with IV-tPA, clot location, stroke etiology, time to treatment, and number of retrieval attempts.
  
  
  CONCLUSIONS
  The HVS in acute ischemic stroke was strongly predictive of successful recanalization using the Merci device. The HVS may indicate thrombi that are less adhesive compared with isodense clots that are more resistant to mechanical retrieval. The absence of HVS on pre-treatment CT may thus suggest the need for a more aggressive or alternative therapeutic approach.
authors.affiliation: Neuro Interventional Service, University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA. michael-froehler@uiowa.edu
authors.forename: Michael T
authors.initials: MT
authors.lastname: Froehler
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tateshima
authors.forename: Gary
authors.initials: G
authors.lastname: Duckwiler
authors.forename: Reza
authors.initials: R
authors.lastname: Jahan
authors.forename: Nestor
authors.initials: N
authors.lastname: Gonzalez
authors.forename: Fernando
authors.initials: F
authors.lastname: Vinuela
authors.forename: David
authors.initials: D
authors.lastname: Liebeskind
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Saver
authors.forename: J Pablo
authors.initials: JP
authors.lastname: Villablanca
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D061185:Mechanical Thrombolysis / Q000295:instrumentation / Q000379:methods*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D020521:Stroke / Q000000981:diagnostic imaging* / Q000628:therapy*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome