Abstract WP231: Detection of Intramural Hematoma by Susceptibility Weighted Image in Vertebral Artery Dissection

Abstract

Objectives The radiologic diagnosis of vertebral artery dissection (VAD) depends on the characteristic intraluminal findings on angiographic study although the pathology of VAD is intramural hematoma. We aimed to know whether ‘intramural hematoma sign (IHS)’ on susceptibility weighted image (SWI) in vertebral artery is specific for VAD. Methods We retrospectively analyzed SWI and phase map images of the consecutive patients with ischemic stroke in the vertebral artery territory from August 2009 to July 2012. We divided the patients into 2 groups; VAD related stroke and atherosclerotic stroke. Diagnostic criteria of VAD related stroke were (a) presence of posterior neck pain or occipital headache and (b) features of VAD at computed tomography angiography or contrast enhanced magnetic resonance angiography or digital subtraction angiography. Angiographic evidence of VAD which is subdivided into three groups: aneurysmal dilatation without stenosis, pearl-and string, and steno-occlusive without aneurysmal dilatation. IHS was considered positive if the patient had (a) eccentric hypointense signal lesion in vertebro-basilar artery on SWI and (b) this signal should be hyperintense on phase map suggesting blood products other than calcification. An experienced neuroradiologist blinded to clinical information was asked to judge the presence of IHS. For statistical analysis, two by two contingency tables by Fisher’s exact test were performed. Results Among the 137 patients with ischemic stroke in the vertebral artery territory, SWI and phase map images were available in 47 patients who were included for our analysis. Among them, 14 patients were diagnosed as an ischemic stroke due to VAD and 33 patients had no VAD (atherosclerotic stroke). Compared to atherosclerotic stroke patients, patients with VAD-related stroke had more headache (64% vs 15%, P=0.016). Among the 14 patients with VAD-related stroke, IHS was detected in 9 cases while only 2 of 33 patients with atherosclerotic stroke showed IHS (sensitivity 64% and specificity 94%). In Fisher’s exact test analysis, the IHS was significantly associated with VAD (p < 0.001). Conclusion The intramural hematoma sign on SWI was significantly associated with vertebral artery dissection.