Purpose. To assess the importance of cerebrovascular CT-angiography (CTA) in the diagnosis of ruptured cerebral aneurysms during an acute period of non-traumatic intracranial hemorrhage, and to identify the causes of errors in the diagnosis of aneurysms on CTA.

Materials and Methods. We analyzed medical records of patients who underwent clipping of aneurysms in the acute period of rupture. We revised CT images of all patients taken both with and without contrast. Then, we compared the findings of cerebrovascular CTA, performed in the emergency setting, with the results of intraoperative data.

Results and discussion. Аccording to the results of CTA, 302 aneurysms were diagnosed in 262 patients, most of the patients (208) were diagnosed with a single aneurysm. CT images of all patients were reinterpreted, and 14 aneurysms were found as a result of secondary evaluation. The sensitivity and overall accuracy of CTA constituted 95.56% and 97.0% respectively compared to intraoperative data. We analyzed the causes of missed cerebral aneurysms on CTA. The main cause of errors was the small size of aneurysms - less than 3 mm, a decreased quality of CT images in the arterial phase due to poor contrast opacification and cerebral vasospasm, as well as challenging localizations of aneurysms.

Conclusion. The study shows that cerebrovascular CTA is a reliable method for detecting aneurysms in the acute period of non-traumatic subrarachnoid hemorrhage. CTA can be used for treatment planning of the patients due to its high sensitivity (96.56%) and overall accuracy (97%).