P08 Detection of cerebral aneurysms in unenhanced CT images of patients with subarachnoid hemorrhage using the sparing aneurysm sign (SAS)

Introduction About 85% of the non-traumatic SAH are caused by ruptured aneurysms1. Identifying those aneurysms as the bleeding cause is essential for further therapy. Aim of study The study evaluates the detection of cerebral aneurysm in unenhanced CT images of patients with subarachnoid hemorrhage by a relative hypodense structure in the hyperdense bleeding, the sparing aneurysm sign (SAS). Methods Three neuroradiologic experienced radiologists rated the aneurysm location and size by applying the SAS in 50 CT-examinations of patients with aneurysmal SAH who underwent an initial CT scan followed by a DSA. The results were analyzed for correlations between aneurysm location, aneurysm size, Fisher-score and the detectability of a SAS. Further a quantitative analysis of the average HU of the aneurysm and the SAH was performed. Results In 75% of the cases the aneurysm was identified correctly just using the SAS, influenced significant by aneurysm location (p=0.019), Fisher-Score (p=0.008) and aneurysm size (p=0.017). The highest rate of aneurysm detection was given for MCA- (90%) and BA-aneurysms (90%), followed by ACOM- (80%) and ACA-aneurysm (80%). The measured aneurysm size in the correctly identified aneurysm significantly corelates to the size measured in the DSA (p<0.001) and a cut point of 51 HU discriminates aneurysm from SAH with a specificity of 92% and a sensitivity of 86% (Youden´s index 0.78). Conclusions The aneurysm location and size can be determined in unenhanced CT images in many cases using the new SAS (sparing aneurysm sign). Whereas quantitative measurements of HU can support the aneurysm detection. References Connolly ES, Rabinstein AA, Carhuapoma JR, et al. Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage. Stroke. 2012;43. Do you have any conflict of interest to declare?: No