The relatively long scan time is still a bottleneck for both clinical applications and research of magnetic resonance imaging. To reduce the data acquisition time, we propose a novel fast magnetic resonance imaging method based on parallel variable-density spiral acquisition, which combines undersampling optimization and nonlocal total variation reconstruction. The undersampling optimization promotes the incoherence of resultant aliasing artifact via the ＂worst-case＂ residual error metric, and thus accelerates the data acquisition. Moreover, nonlocal total variation reconstruction is utilized to remove such an incoherent aliasing artifact and so improve image quality. The feasibility of the proposed method is demonstrated by both numerical phantom simulation and in vivo experiment. The experimental results show that the proposed method can achieve high acceleration factor and effectively remove an aliasing artifact from data undersampling with well-preserved image details. The image quality is better than that achieved with the total variation method.
Background:Carotid atherosclerotic plaque is identified as one of the main sources of ischaemic stroke.However,the prevalence of carotid high-risk atherosclerotic plaque in Chinese patients with ischaemic cerebrovascular events has been inconsistently reported and needs to be investigated in a large population.Objectives:The primary objective of CARE II study was to determine the prevalence and characteristics of high-risk features of atherosclerotic plaques in the carotid arteries in Chinese patients with recent ischaemic stroke or transient ischaemia attack(TIA).The relationship between carotid plaque features and cerebral infarcts,the differences of carotid plaque patterns among different regions of China and the gender specific characteristics of carotid plaque will be also determined.Study design:The CARE II study will enrol 1000 patients with recent ischaemic stroke or TIA and carotid plaque from 13 hospitals and medical centres across China.In this cross-sectional,non-randomised,observational,multicentre study,all patients will undergo carotid artery MRI of bilateral carotid arteries and routine brain MRI with standardised protocols.The MRI will be interpreted at core reading centres to evaluate the characteristics of morphology and compositions of carotid plaque.Conclusions:This is a cross-sectional,multicentre study to investigate the prevalence and characteristics of high-risk atherosclerotic carotid plaque in Chinese patients with stroke and TIA by using high-resolution MRI of vessel wall.This trial is sufficiently powered to demonstrate the prevalence of carotid high-risk plaque and to explore regional differences in Chinese patients who suffered stroke.
Xihai ZhaoRui LiDaniel S HippeThomas S HatsukamiChun YuanCARE-II Investigators
