Clinical Radiology Scientific Exhibits

Body: Extracranial stenosis (ECS) refers to vascular disease outside the skull, primarily referring to the carotid and vertebral arteries. Intracranial stenosis (ICS) primarily refers to the Circle of Willis. It is well-established that extracranial carotid artery stenosis is associated with a higher stroke risk, with increasing disease burden being a crucial factor in treatment decisions. However, other such steno-occlusive lesions have been investigated, but their effect on stroke risk is less well-established. Diabetes and ischemic heart disease (IHD) have been shown to be more prevalent in patients with both ECS and ICS. Purpose: To investigate if there is a clinically significant relationship between ICS and ECS with transient ischemic attacks (TIAs), stroke and its risk factors. Methods and Materials: 415 consecutive patients that presented to a tertiary hospital with stroke were retrospectively analysed, with 158 excluded for incomplete CT angiogram (CTA) results. ICS and ECS severity was based on grading used in the WASID and SAMPRISS trials. Presence of stenosis was based on CTA findings. Association between ICS, ECS and stroke risk factors was analysed using the student T-test. Association between ECS and ICS was analysed using the Pearson’s chi-squared test. Results: There was a statistically significant association found between presence of ICS with AF, hypertension, IHD and diabetes (p < 0.001), while a statistically significant association with presence of ECS was only found with AF, hypertension and IHD (p < 0.001). However, when this is divided into significant versus non-significant disease burden, significant ICS only shows a substantial link with AF (21% vs 44%;p < 0.05) while significant ECS demonstrates a male preponderance (51% vs. 81%;p < 0.05). The presence of both ICS and ECS was associated with an increased prevalence of AF, hypertension, IHD and diabetes (p < 0.001). ICS and/or ECS was present in 80% of patients with ischemic stroke, 78% with TIAs but comparatively only in 56% of those diagnosed as ‘mimics’ (p < 0.05). A significant association is also present between ECS and ICS with 68% of patients with stenotic disease demonstrating both (ECS PPV for ICS=0.85, chi-square p-value <0.001). Most steno-occlusive lesions were also bilateral for ICS and ECS at 80% and 61%, respectively. Conclusions: The findings suggest that there is a significant association between the presence of ICS and ECS with the occurrence of ischemic stroke and TIAs as well as with some well-known stroke risk factors. The association between ECS and ICS suggests that ECS may represent a more severe overall disease burden. References 1. Shakur SF, Hrbac T, Alaraj A, Du X, Aletich VA, Charbel FT, et al. Effects of extracranial carotid stenosis on intracranial blood flow. Stroke. 2014;45(11):3427–9. 2. Poggio E. , Glynn R. , Schein O. , Seddon J., Shannon M. , Scardino V. , et al. N Engl J Med,. 2010;321(12):779–83. 3. Kasner SE, Chimowitz MI, Lynn MJ, Howlett-smith H, Stern BJ, Hertzberg VS, et al. Predictors of Ischemic Stroke in the Territory of a Symptomatic Intracranial Arterial Stenosis. 2006; 4. Chimowitz MI, Lynn MJ, Howlett-smith H, Stern BJ, Hertzberg VS, Ph D, et al. Comparison of Warfarin and Aspirin for Symptomatic Intracranial Arterial Stenosis. 2005;1305–16. 5. Nijasri C, Chutinetr A. Risk factors for atherosclerosis of cervicocerebral arteries : Intracranial versus extracranial. Neuroepidemiology. 2003; Editorial material and organization © 2018 Royal Australian and New Zealand College of Radiologists. Copyright of individual abstracts remains with the authors. Clinical Radiology Scientific Exhibits 125