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Background: Little is known about internal carotid artery (ICA) hemodynamics in patients with moyamoya angiopathy (MMA) and its role in cerebrovascular events. Purpose: To characterize ICA hemodynamics in MMA patients by 4D flow MRI and investigate its relationship with cerebrovascular events. Study Type: Prospective. Subjects: Seventy MMA patients (50 years old ± 9, 30 males). Field Strength/Sequence: Time‐resolved three‐directional velocity encoded fast field echo sequence (4D flow) MRI, T1‐weighted fast field echo sequence, T2 weighted turbo spin echo sequence, diffusion weighted echo planar imaging; T2‐weighted fluid‐attenuated inversion recovery turbo spin echo sequence, susceptibility weighted fast field echo sequence, and time‐of‐flight MR angiography fast field echo sequence at 3.0T. Assessment: ICA hemodynamics (maximum and average velocity [Vmax, Vavg], average blood flow [Flowavg], and wall shear stress) were analyzed based on 4D flow data. Cerebral infarction, defined as the occurrence of events, in 124 brain hemispheres was determined according to clinical symptoms and conventional brain MR imaging. Statistical Tests: The independent‐samples T test was used to evaluate differences in ICA hemodynamics between infarcted and non‐infarcted hemispheres. Binary logistic regression was performed to investigate the relationship between ICA hemodynamics and events. A P value < 0.05 was considered statistically significant. Results: Sixty‐one infarcted hemispheres (eight hemispheres with acute ischemic damage, 30 with chronic ischemic damage, and 23 with chronic hemorrhagic damage) had cerebrovascular events and 63 non‐infarcted hemispheres did not. The hemodynamic parameters in the infarcted hemispheres (Vmax: P < 0.001; Vavg: P = 0.003; and Flowavg: P = 0.004) were significantly lower than those in the non‐infarcted hemispheres. However, Vmax (P = 0.052), Vavg (P = 0.107), and Flowavg (P = 0.074) were not significantly different among hemispheres with acute ischemic lesions, chronic ischemic lesions and chronic hemorrhagic lesions. Vmax (odds ratio 3.033, 95% CI: 1.075–8.562) was independently associated with cerebrovascular events. Data Conclusion: Vmax maybe a higher risk factor of cerebrovascular events in MMA patients. Evidence Level: 2 Technical Efficacy Stage: 3 [ABSTRACT FROM AUTHOR]

The structural covariance network (SCN) has provided a perspective on the large‐scale brain organization impairment in the Alzheimer's Disease (AD) continuum. However, the successive structural impairment across brain regions, which may underlie the disrupted SCN in the AD continuum, is not well understood. In the current study, we enrolled 446 subjects with AD, mild cognitive impairment (MCI) or normal aging (NA) from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. The SCN as well as a casual SCN (CaSCN) based on Granger causality analysis were applied to the T1‐weighted structural magnetic resonance images of the subjects. Compared with that of the NAs, the SCN was disrupted in the MCI and AD subjects, with the hippocampus and left middle temporal lobe being the most impaired nodes, which is in line with previous studies. In contrast, according to the 194 subjects with records on CSF amyloid and Tau, the CaSCN revealed that during AD progression, the CaSCN was enhanced. Specifically, the hippocampus, thalamus, and precuneus/posterior cingulate cortex (PCC) were identified as the core regions in which atrophy originated and could predict atrophy in other brain regions. Taken together, these findings provide a comprehensive view of brain atrophy in the AD continuum and the relationships among the brain atrophy in different regions, which may provide novel insight into the progression of AD. [ABSTRACT FROM AUTHOR]

Background: Carotid atherosclerotic plaque rupture is an important source of ischemic stroke. However, the prevalence of high-risk plaque (HRP) defined as plaques with luminal surface disruption, a lipid-rich necrotic core occupying >40% of the wall, or intraplaque hemorrhage in Chinese population remains unclear. This study uses carotid magnetic resonance imaging (CMRI) to investigate HRP prevalence in carotid arteries of Chinese patients with cerebrovascular symptoms., Methods and Results: Patients with cerebral ischemic symptoms in the anterior circulation within 2 weeks and carotid plaque determined by ultrasound were recruited and underwent CMRI. The HRP features were identified and compared between symptomatic and asymptomatic arteries. Receiver-operating-characteristic analysis was used to calculate area-under-the-curve (AUC) of stenosis and maximum wall thickness for discriminating presence of HRP. In 1047 recruited subjects, HRP detected by CMRI was nearly 1.5 times more prevalent than severe stenosis (≥50%) in this cohort (28% versus 19%, P <0.0001). Approximately two thirds of HRPs were found in arteries with <50% stenosis. The prevalence of HRP in symptomatic carotid arteries was significantly higher than that of the contralateral asymptomatic carotid arteries (23.0% versus 16.4%, P =0.001). Maximum wall thickness was found to be a stronger discriminator than stenosis for HRP (AUC: 0.93 versus 0.81, P <0.0001)., Conclusions: There are significantly more high-risk carotid plaques than carotid arteries with ≥50% stenosis in symptomatic Chinese patients. A substantial number of HRPs were found in arteries with lower grade stenosis and maximum wall thickness was a stronger indicator for HRP than luminal stenosis., Clinical Trial Registration: URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02017756., (© 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.)