title: CT perfusion during delayed cerebral ischemia after subarachnoid hemorrhage: distinction between reversible ischemia and ischemia progressing to infarction.
abstract: BACKGROUND
  Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) can be reversible or progress to cerebral infarction. In patients with a deterioration clinically diagnosed as DCI, we investigated whether CT perfusion (CTP) can distinguish between reversible ischemia and ischemia progressing to cerebral infarction.
  
  
  METHODS
  From a prospectively collected series of aSAH patients, we included those with DCI, CTP on the day of clinical deterioration, and follow-up imaging. In qualitative CTP analyses (visual assessment), we calculated positive and negative predictive value (PPV and NPV) with 95% confidence intervals (95%CI) of a perfusion deficit for infarction on follow-up imaging. In quantitative analyses, we compared perfusion values of the least perfused brain tissue between patients with and without infarction by using receiver-operator characteristic curves and calculated a threshold value with PPV and NPV for the perfusion parameter with the highest area under the curve.
  
  
  RESULTS
  In qualitative analyses of 33 included patients, 15 of 17 patients (88%) with and 6 of 16 patients (38%) without infarction on follow-up imaging had a perfusion deficit during clinical deterioration (p = 0.002). Presence of a perfusion deficit had a PPV of 71% (95%CI: 48-89%) and NPV of 83% (95%CI: 52-98%) for infarction on follow-up. Quantitative analyses showed that an absolute minimal cerebral blood flow (CBF) threshold of 17.7 mL/100 g/min had a PPV of 63% (95%CI: 41-81%) and a NPV of 78% (95%CI: 40-97%) for infarction.
  
  
  CONCLUSIONS
  CTP may differ between patients with DCI who develop infarction and those who do not. For this purpose, qualitative evaluation may perform marginally better than quantitative evaluation.
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, Utrecht, The Netherlands. C.H.P.Cremers-2@umcutrecht.nl.|Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands. C.H.P.Cremers-2@umcutrecht.nl.
authors.forename: Charlotte H P
authors.initials: CH
authors.lastname: Cremers
authors.affiliation: Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Pieter C
authors.initials: PC
authors.lastname: Vos
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Irene C
authors.initials: IC
authors.lastname: van der Schaaf
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Birgitta K
authors.initials: BK
authors.lastname: Velthuis
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, Utrecht, The Netherlands.
authors.forename: Mervyn D I
authors.initials: MD
authors.lastname: Vergouwen
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, Utrecht, The Netherlands.
authors.forename: Gabriel J E
authors.initials: GJ
authors.lastname: Rinkel
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: Dankbaar
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000209:etiology*; D002533:Cerebral Angiography / Q000379:methods; D002544:Cerebral Infarction / Q000000981:diagnostic imaging* / Q000209:etiology*; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D018450:Disease Progression; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D013345:Subarachnoid Hemorrhage / Q000150:complications* / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide
keywords: CT perfusion; Delayed cerebral ischemia; Subarachnoid hemorrhage