title: Early CT perfusion mismatch in acute stroke is not time-dependent but relies on collateralization grade.
abstract: BACKGROUND
  Factors that determine the extent of the penumbra in the initial diagnostic workup using whole brain CT Perfusion (WB-CTP) remain unclear. The purpose of the current study was to determine a possible dependency of the initial mismatch size between cerebral blood flow (CBF) and cerebral blood volume (CBV) from time after symptom onset, leptomeningeal collateralization, and occlusion localization in acute middle cerebral artery (MCA) infarctions.
  
  
  METHODS
  Out of an existing cohort of 992 consecutive patients receiving multiparametric CT scans including WB-CTP due to suspected stroke, we included patients who had (1) a witnessed time of symptom onset, (2) an infarction of the MCA territory as documented by follow-up imaging, and (3) an initial CBF volume of >10 ml. CBF and CBV lesion sizes, collateralization grade, and the site of occlusion were determined.
  
  
  RESULTS
  We included 103 patients. Univariate analysis showed that time from symptom onset (168 +/- 91.2 min) did not correlate with relative or absolute mismatch volumes (p = 0.458 and p = 0.921). Higher collateralization gradings were associated with small absolute mismatch volumes (p = 0.004 and p < 0.001). Internal carotid artery (ICA) occlusions were associated with large absolute mismatch volumes (p = 0.004). Multivariate analysis confirmed that ICA occlusion was associated with large absolute mismatch volumes (p = 0.005), and high collateral grade was associated with small absolute mismatch volumes (p = 0.017).
  
  
  CONCLUSIONS
  There is no significant correlation between initial CTP mismatch and time after symptom onset. Predictors of mismatch size include the extent of the collaterals and a proximal location of the occlusion.
authors.affiliation: Department of Neurology, University of Munich Hospitals, Grosshadern Campus, Marchioninistr. 15, 81377, Munich, Germany. Louisa.vonBaumgarten@med.uni-muenchen.de.
authors.forename: Louisa
authors.initials: L
authors.lastname: von Baumgarten
authors.affiliation: Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Munich, Germany.
authors.forename: Kolja M
authors.initials: KM
authors.lastname: Thierfelder
authors.affiliation: Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Munich, Germany.
authors.forename: Sebastian E
authors.initials: SE
authors.lastname: Beyer
authors.affiliation: Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Munich, Germany.
authors.forename: Alena B
authors.initials: AB
authors.lastname: Baumann
authors.affiliation: Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Munich, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Bollwein
authors.affiliation: Department of Neuroradiology, Ludwig-Maximilians-University Hospital Munich, Munich, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Janssen
authors.affiliation: Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Munich, Germany.
authors.forename: Maximilian F
authors.initials: MF
authors.lastname: Reiser
authors.affiliation: Department of Neurology, University of Munich Hospitals, Grosshadern Campus, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Straube
authors.affiliation: Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Munich, Germany.
authors.forename: Wieland H
authors.initials: WH
authors.lastname: Sommer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001810:Blood Volume / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D015331:Cohort Studies; D003097:Collateral Circulation / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D020521:Stroke / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D013997:Time Factors; D014057:Tomography, X-Ray Computed
keywords: Acute ischemic stroke; CT perfusion; Flow-volume mismatch; Leptomeningeal collateralization; Penumbral imaging