Differential Middle Cerebral Artery Plaque Characteristics in Patients With Transient Ischemic Attack and Ischemic Stroke: A High-Resolution MR Vessel Wall Imaging Study

Introduction: Intracranial atherosclerotic disease (ICAD) correlates highly with transient ischemic attack (TIA) and acute ischemic stroke (AIS). Magnetic Resonance (MR) vessel wall imaging (VWI) is an emerging non-invasive imaging modality for directly assessing ICAD lesions. Methods: We retrospectively analyzed MR-VWI from 42 TIA patients and 45 AIS patients with ICAD. All patients fulfilled the following criteria: (1) stenosis >30% of a middle cerebral artery (MCA), (2) symptoms contralateral to stenotic MCA, (3) no coexisting stenosis at other major vessels; (4) lack of compelling evidence to other etiologies of stroke/TIA. Vascular lesions were analyzed with MR-VWI with respect to the stenosis degree, vessel wall irregularity, plaque burden (PB), remodeling index (RI), plaque-wall contrast ratio (CR) and plaque enhancement grade (EG). Results: EG (OR 3.88, 95%CI 1.42-10.57, P=0.006) was a risk factor for AIS while PB (OR 0.65, 95%CI 0.27-1.54, P=0.008) was a risk factor for TIA. In patients with 30-70% degree stenosis, CR (OR 5.38, 95%CI 1.39-20.75, P=0.008) was a risk factor for stroke, while PB (OR 0.4, 95%CI 0.1-1.65, P=0.006) remained a risk factor for TIA. Conclusions: In our study, PB appeared as a risk factor for TIA but not for AIS. This suggests that unstable plaque accounting for AIS may have a wide range of PB. We further found that CR and EG are more associated with AIS than TIA. Lesions with high CR and strong enhancement may be more prone to producing the permanent ischemic injury. Further study is needed to elucidate the role of MR-VWI in differential diagnosis and management of TIA and AIS.