CT angiography in non-traumatic subarachnoid hemorrhage: the importance of arterial attenuation for the detection of intracranial aneurysms.

BackgroundComputed tomography angiography (CTA) is today the primary method for the detection of intracranial aneurysms. The technique has evolved considerably during the last decade, and it is important to establish criteria for high image quality, especially with regard to improving the diagnosis of small aneurysms.PurposeTo evaluate diagnostic accuracy and image quality by arterial attenuation of CTA in patients with non-traumatic subarachnoid hemorrhage (SAH).Material and MethodsBetween 2005 and 2011, CTA and digital subtraction angiography (DSA) were performed in 326 patients with non-traumatic SAH. Sensitivity and specificity for aneurysm detection were evaluated per patient, per aneurysm, and per ruptured aneurysm. The image quality of CTA was evaluated by arterial attenuation measurements (mean Hounsfield units [HU]) in the internal carotid artery (ICA).ResultsIn all, 285 aneurysms in 235 patients were detected by DSA, 19 aneurysms were missed on CTA, and 223 aneurysms were classified as ruptured....