Validity of prediction of the site of ruptured intracranial aneurysms withCT

Objective: We studied the diagnostic power of blood distribution on CT (per formed within 72 hours after the bleed) for the site of ruptured aneurysm i n 168 consecutive patients with subarachnoid hemorrhage with either a singl e aneurysm or no aneurysm on the four-vessel angiogram or postmortem examin ation. Methods: A neurosurgeon and a neuroradiologist blind to the results of the angiography independently scored the distribution of blood on the CT and predicted the site of the ruptured aneurysm. Results: Overall agreemen t among raters was 52% and chance-adjusted agreement (kappa) was 0.42 (weig hted kappa value 0.47). A parenchymal cerebral hematoma was an excellent pr edictor for the site of a ruptured aneurysm but was present in only a minor ity of cases (15%). The next most valid predictor was blood distribution on CT in patients with a ruptured anterior cerebral artery aneurysm or anteri or communicating artery aneurysm (sensitivity 0.79, specificity 0.96, and p ositive predictive value 0.79 for rater 1; sensitivity 0.77, specificity 0. 97, and positive predictive value 0.90 for rater 2). The validity of the pr edictive value of blood distribution on CT in patients with a ruptured aneu rysm of the middle cerebral artery, internal carotid artery, or posterior c irculation arteries was either inconsistent between raters or low. Conclusi on: With the exception of the presence of a parenchymal hematoma, the site of the ruptured aneurysm can be predicted by CT only in ruptured anterior c erebral artery or anterior communicating artery aneurysms.