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Contains fulltext : 207086.pdf (publisher's version ) (Open Access), Background Rupture of a vulnerable carotid atherosclerotic plaque is an important underlying cause of ischemic stroke. Increased leaky plaque microvasculature may contribute to plaque vulnerability. These immature microvessels may facilitate entrance of inflammatory cells into the plaque. The objective of the present study is to investigate whether there is a difference in plaque microvasculature (the volume transfer coefficient K(trans)) between the ipsilateral symptomatic and contralateral asymptomatic carotid plaque using noninvasive dynamic contrast-enhanced magnetic resonance imaging. Methods and Results Eighty-eight patients with recent transient ischemic attack or ischemic stroke and ipsilateral >2 mm carotid plaque underwent 3 T magnetic resonance imaging to identify plaque components and to determine characteristics of plaque microvasculature. The volume transfer coefficient K(trans), indicative for microvascular density, flow, and permeability, was calculated for the ipsilateral and asymptomatic plaque, using a pharmacokinetic model (Patlak). Presence of a lipid-rich necrotic core, intraplaque hemorrhage, and a thin and/or ruptured fibrous cap was assessed on multisequence magnetic resonance imaging . We found significantly lower K(trans) in the symptomatic carotid plaque compared with the asymptomatic side (0.057+/-0.002 min(-1) versus 0.062+/-0.002 min(-1); P=0.033). There was an increased number of slices with intraplaque hemorrhage (0.9+/-1.6 versus 0.3+/-0.8, P=0.002) and lipid-rich necrotic core (1.4+/-1.9 versus 0.8+/-1.4, P=0.016) and a higher prevalence of plaques with a thin and/or ruptured fibrous cap (32% versus 17%, P=0.023) at the symptomatic side. Conclusions K(trans) was significantly lower in symptomatic carotid plaques, indicative for a decrease of plaque microvasculature in symptomatic plaques. This could be related to a larger amount of necrotic tissue in symptomatic plaques. Clinical Trial Registration URL : http://www.clinicaltrials.g

Item does not contain fulltext, BACKGROUND: Carotid atherosclerosis is an important cause of stroke. Intra-plaque haemorrhage (IPH) on magnetic resonance imaging (MRI) increases stroke risk. Development of IPH is only partly understood. Thrombin is an essential enzyme in haemostasis. Experimental animal studies have shown conflicting results on the relation between thrombin and plaque vulnerability. We hypothesize that decreased thrombin generation (TG) is associated with IPH and plaque vulnerability. OBJECTIVE: This article investigates whether TG is associated with IPH and other features of plaque vulnerability in stroke patients. METHODS: Recently symptomatic stroke patients underwent carotid MRI and blood sampling. MRI plaque features include plaque burden, presence of IPH, amount of lipid-rich necrotic core (LRNC), calcified tissue and fibrous tissue (% of total wall volume). TG was assessed in platelet-poor plasma and expressed as: peak height (PH) and endogenous thrombin potential (ETP). MR images could be analysed in 224 patients. Blood samples were available in 161 of 224 patients. Binary multivariate logistic and linear regression were used to investigate the association between TG and MRI plaque features. RESULTS: IPH and LRNC were present in 65 (40%) and 102 (63%) of plaques. There were no significant associations between TG and IPH; PH odds ratio (OR) = 1, 95% confidence interval (CI): 0.76 to 1.45 and ETP OR = 1, 95% CI: 0.73 to 1.37. After correction for age, sex and hypercholesterolaemia, the association was weak but non-significant; PH: OR = 0.76, 95% CI: 0.52 to 1.10 and ETP: OR = 0.73, 95% CI: 0.53 to 1.37. CONCLUSION: Features of carotid plaque on MRI show no significant association with TG in stroke patients. Systemic TG does not seem to be an important factor in IPH development.

Item does not contain fulltext, Local arterial stiffness can be assessed with high accuracy and precision by measuring arterial distension on the basis of phase tracking of radiofrequency ultrasound signals acquired at a high frame rate. However, in clinical practice, B-mode ultrasound registrations are made at a low frame rate (20-50 Hz). We compared the accuracy and intra-subject precision of edge tracking and phase tracking distension in symptomatic carotid artery patients. B-mode ultrasound recordings (40 mm, 37 fps) and radiofrequency recordings (31 lines covering 29 mm, 300 fps) were acquired from the left common carotid artery of 30 patients (aged 45-88 y) with recent cerebrovascular events. To extract the distension, semi-automatic echo edge and phase tracking algorithms were applied to B-mode and radiofrequency recordings, respectively. Both methods exhibited a similar intra-subject precision for distension (standard deviation = 44 mum and 47 mum, p = 0.66) and mean distension (difference: -6 +/- 69 mum, p = 0.67). Intra-subject distension inhomogeneity tends to be larger for edge tracking (difference: 15 +/- 35 mum, p = 0.04). Standard B-mode scanners are suitable for measuring local artery characteristics in symptomatic carotid artery patients with good precision and accuracy.