Abstract 2771: Incidence of High Risk Atherosclerotic Lesions in Intracranial and Extracranial Carotid Arteries in Patients with Acute Ischemic Stroke: A 3.0T Magnetic Resonance Imaging Study

Abstract

Introduction Rupture of vulnerable atherosclerotic plaques in the intracranial and extracranial carotid arteries could trigger ischemic stroke. However, the incidence of high risk atherosclerotic lesions in these vascular beds is not well known. This study sought to investigate the incidence of high risk atherosclerotic lesions in intracranial and extracranial carotid arteries in stroke patients using magnetic resonance (MR) imaging. Methods Seventy-five patients (mean age 62.7 years, 56 males) with acute ischemic stroke underwent MR imaging for index carotid arteries, assigned as the same side as the brain lesions, with a Philips 3.0T MR scanner. Intracranial carotid MR angiography was performed using 3D TOF sequence with FOV of 23 × 23 cm 2 , matrix of 256 × 256, and a slice thickness of 1mm. The multi-contrast vessel wall images (3D TOF, T1W, T2W, and MP-RAGE) were acquired for extracranial carotid arteries with FOV of 14 × 14 cm 2 , matrix of 256 × 256, and slice thickness of 2 mm. The intracranial artery includes middle cerebral artery (MCA), anterior cerebral artery (ACA), and posterior cerebral artery (PCA). The extracranial carotid artery was divided into internal carotid artery (ICA), bulb, and common carotid artery (CCA). Luminal stenosis for each intracranial and extracranial carotid segment was measured and graded (normal or mild = 0-29%, moderate =30-69%, severe=70-99%). Normalized wall index (NWI = wall area/total vessel area × 100%), and presence/absence of calcification, lipid-rich necrotic core (LRNC), and intraplaque hemorrhage (IPH) and/or fibrous cap rupture in each extracranial carotid segment were determined. Results MCAs developed more severe stenotic lesions (24.6%), followed by extracranial carotids (16.5%), PCAs (5.4%), and ACAs (4.1%) in stroke patients ( Figure 1 A). For extracranial carotid arteries, ICAs showed the largest plaque burden as measured by NWI (44.3%±13.1%), followed by bulbs (39.4%±13%), and CCAs (37%±6.8%). Compared to CCAs, ICAs and bulb regions had more LRNCs (38.4% and 49.3% for ICA and bulb respectively) and IPH and/or rupture (11% and 9.6% for ICA and bulb respectively) ( Figure 1 B). Conclusions In patients with acute ischemic stroke, high risk atherosclerotic plaques can be found in both intracranial and extracranial carotid arteries, particularly in the MCA, ICA and bulb regions. Compared to extracranial carotid arteries, intracranial arteries develop more high risk lesions. The findings of this study suggest the necessity for early screening to detect high risk atherosclerotic lesions in these carotid vascular beds prior to cerebravascular events.