Patterns of Cerebral Perfusion in Patients with Asymptomatic Internal Carotid Artery Disease

Abstract

Background: The perfusion profile of patients with asymptomatic internal carotid artery (ICA) disease has not been well studied. The purpose of this study is to describethe perfusion patterns of patients with asymptomatic ICA disease using computed tomography perfusion (CTP) and its potential value in identifying patients at higher risk for transient ischemic attacks (TIAs) or strokes. Methods: We analyzed 32 patients with asymptomatic high grade ICA disease who had CTP and computed tomography angiography (CTA) of the head and neck. Twenty-four patients had severe ICA stenosis and eight had ICA occlusion. The degree of ipsilateral external carotid artery (ECA) and contralateral ICA stenosis, patency of the anterior communicating artery (ACOM), A1 segment and posterior communicating artery (PCOM) were evaluated in all patients. Results: Sixteen patients had normal CTP and the other 16 patients had cerebral hypoperfusion, characterized by abnormalities in one or more of the three perfusion maps. Ipsilateral hypoplastic A1 segment was more frequent in the group with cerebral hypoperfusion (p = 0.025). Ipsilateral TIAs occurred in two patients, both with cerebral hypoperfusion. Conclusion: Cerebral hypoperfusion is present in half of the patients with asymptomatic ICA disease, predominantly in patients with a hypoplastic ipsilateral A1 segment. These patients likely represent a higher-risk group for symptomatic brain ischemia.

Cerebral Perfusion Affects the Risk of Ischemia during Carotid Artery Stenting

“…Our finding of more impaired cerebral perfusion in hemispheres with new ischemic lesions than in hemispheres without is in keeping with previous studies showing that in patients with carotid stenosis or occlusion, cerebral hemodynamic impairment, as defined by an exhausted cerebrovascular reactivity, increases the risk of ischemic stroke [12,13,39]. Support for a synergistic effect of hemodynamic and thromboembolic factors has also been provided by a study demonstrating that the flow velocity in the MCA was lower in patients with symptoms of cerebral ischemia during carotid artery stenting than in those without symptoms [40].…”

Low Level of Low-Density Lipoprotein Cholesterol Increases Hemorrhagic Transformation in Large Artery Atherothrombosis but Not in Cardioembolism

“…The stenosed proximal arteries may damage cerebral neurovascular units of relevant territory in various ways. The narrow proximal larger arteries are known to associate with low perfusion state in the brain, 33 and microemboli are reported to increase in stenosis of proximal arteries. 34 In contrast, CE, by definition, implies heart-originating embolism without meaningful cerebral arterial stenosis, 14 and may have relatively intact neurovascular unit without long-standing subclinical injuries.…”

Intraprocedural Changes in Angiographic Cerebral Circulation Time Predict Cerebral Blood Flow After Carotid Artery Stenting

“…9,14,32,33) To obtain objective measurements in this study, the CCT was determined based on time-density curves generated from a ROI in the terminal portion of the ICA and a ROI in the cortical vein draining the territory of the MCA. 14) Perfusion CT is an excellent diagnostic tool that is useful in patients with cerebral ischemia 4,6,30,31) to quickly provide semi-quantitative information on the CBF without requiring special equipment or reagents. However, several factors such as the patient's physique, heart rate, and cardiac output, and differences in ROI placement may affect the measurements, so perfusion CT cannot be regarded as a reliable quantitative method.…”