title: Predictive value of thrombus attenuation on thin-slice non-contrast CT for persistent occlusion after intravenous thrombolysis.
abstract: BACKGROUND
  In stroke erythrocyte-rich thrombi are more sensitive to intravenous thrombolysis with recombinant tissue plasminogen activator (IV-rtPA) and have higher density on non-contrast CT (NCCT). We investigated the relationship between thrombus density and recanalization and whether persistent occlusions can be predicted by Hounsfield unit (HU) measurements.
  
  
  METHODS
  In 88 IV-rtPA-treated patients with intracranial ICA or MCA occluding thrombus and follow-up imaging, thrombus and contralateral vessel attenuation measurements were performed on thin-slice NCCT. Mean absolute and relative HU were compared between patients with persistent occlusion (modified Thrombolysis in Cerebral Infarction system, grade 0/1/2a) and recanalization (grade 2b/3). Univariate and multivariate (adjusted for stroke subtype, clot burden score, occlusion site and time to thrombolysis) odds ratios for persistent occlusion were calculated. Additional prognostic value for persistent occlusion was estimated by adding HU measurements to the area under the curve (AUC) of known determinants and calculating optimal cut-off values.
  
  
  RESULTS
  Patients with persistent occlusion (n = 19) had significant lower mean HU (absolute 52.2 ± 9.5, relative 1.29 ± 0.20) compared to recanalization (absolute 63.1 ± 10.7, relative 1.54 ± 0.23, both p < 0.0001). Odds ratios for persistent occlusion were 3.1 (95% confidence interval, CI 1.6-6.0) univariate and 3.1 (95% CI 1.7-5.7) multivariate per 10 absolute HU decrease and 3.2 (95% CI 1.6-6.5) univariate and 4.1 (95% CI 1.8-9.1) multivariate per 0.20 relative HU decrease. Attenuation measurements significantly increased the AUC (0.67) of the known determinants to 0.84 (absolute HU) and 0.86 (relative HU). Cut-off values of <56.5 absolute HU and <1.38 relative HU showed optimal predictive values for persistent occlusion.
  
  
  CONCLUSIONS
  Thrombus density is related to recanalization rate. Lower absolute and relative HU are independently related to persistent occlusion and HU measurements significantly increase discriminative performances of known recanalization determinants.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: J M
authors.initials: JM
authors.lastname: Niesten
authors.forename: I C
authors.initials: IC
authors.lastname: van der Schaaf
authors.forename: Y
authors.initials: Y
authors.lastname: van der Graaf
authors.forename: L J
authors.initials: LJ
authors.lastname: Kappelle
authors.forename: G J
authors.initials: GJ
authors.lastname: Biessels
authors.forename: A D
authors.initials: AD
authors.lastname: Horsch
authors.forename: J W
authors.initials: JW
authors.lastname: Dankbaar
authors.forename: M J A
authors.initials: MJ
authors.lastname: Luitse
authors.forename: T
authors.initials: T
authors.lastname: van Seeters
authors.forename: E J
authors.initials: EJ
authors.lastname: Smit
authors.forename: W P Th M
authors.initials: WP
authors.lastname: Mali
authors.forename: B K
authors.initials: BK
authors.lastname: Velthuis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D020767:Intracranial Thrombosis / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D020521:Stroke / Q000188:drug therapy; D015912:Thrombolytic Therapy / Q000379:methods; D013927:Thrombosis / Q000000981:diagnostic imaging*; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D010959:Tissue Plasminogen Activator