title: Value of the quantity and distribution of subarachnoid haemorrhage on CT in the localization of a ruptured cerebral aneurysm.
abstract: BACKGROUND
  Computed tomography (CT) is the "gold standard" for detecting subarachnoid haemorrhage (SAH) and digital subtraction angiography (DSA) for visualising the vascular pathology. We studied retrospectively 180 patients with subarachnoid haemorrhage (SAH) who underwent first non-enhanced computed tomography (CT), then digital subtraction angiography (DSA) and finally operative aneurysm clipping. Our aim was to assess if the location of the ruptured aneurysm could be predicted on the basis of the quantity and distribution of haemorrhage on the initial CT scan.
  
  
  METHODS
  180 patients with SAH were retrospectively studied. All the CT and DSA examinations were performed at the same hospital. CT was performed within 24 hours after the initial haemorrhage. DSA was performed after the CT, within 48 hours after the initial haemorrhage. Two neuroradiologists, blind to the DSA results, analysed and scored independently the quantity and distribution of the haemorrhage and predicted the site of the ruptured aneurysm on the basis of the non-enhanced CT. DSA provided the location of the ruptured aneurysm. All the patients were operated upon, and the location of the ruptured aneurysm was determined.
  
  
  RESULTS
  The overall reliability value (kappa-value) between the two neuroradiologists for locating all ruptured aneurysms was 0.780. The corresponding value for the right MCA was 0.911, that for the left MCA 0.877 and that for the AcoA 0.736. Not all of the kappa-values were calculated, either because the location of the rupture was constant or because the number of ruptures in the vessel was too small. Subarachnoid haemorrhage with a parenchymal hematoma is an excellent predictor of the site of the ruptured aneurysm with a statistical significance of p=0.003.
  
  
  CONCLUSIONS
  The quantity and pattern of the blood clot on CT within the day of onset of SAH is a reliable and quick tool for locating a ruptured MCA or AcoA aneurysm. It is not, however, reliable for locating other ruptured aneurysms. Subarachnoid haemorrhage with a parenchymal hematoma is an excellent predictor of the site of a ruptured aneurysm.
authors.affiliation: Department of Diagnostic and Interventional Radiology, Oulu University Hospital, PI-50 90029 Oulu, Finland. ari.karttunen@ppshp.fi
authors.forename: A I
authors.initials: AI
authors.lastname: Karttunen
authors.forename: P H
authors.initials: PH
authors.lastname: Jartti
authors.forename: V A
authors.initials: VA
authors.lastname: Ukkola
authors.forename: J
authors.initials: J
authors.lastname: Sajanti
authors.forename: M
authors.initials: M
authors.lastname: Haapea
mesh_terms: D000328:Adult; D000368:Aged; D017542:Aneurysm, Ruptured / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D015901:Angiography, Digital Subtraction; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000601:surgery; D014057:Tomography, X-Ray Computed