Опыт использования акустического доплеровского измерителя течений (АDCP) в условиях Черного моря

В статье излагается методика проведения измерений Lowered ADCP и обработки первичной информации. При последующей обработке данных широко использовался опыт МГИ НАНУ с аналогичными акустическими измерителями течений в 80-е гг. В результате обобщен опыт применения Lowered ADCP в условиях Черного моря, даны алгоритмы обработки данных, приведены профили абсолютной скорости течений на ряде станций и показано, что предлагаемый подход дает более адекватную качественную и количественную оценку профиля скорости течения, чем известные методы.The methods of measurements with Lowered ADCP and processing of the initial information are presented. During the following data processing the experience of Marine Hydrophysical Institute of NAS of Ukraine with the similar acoustic currents meters in the 80-ies was widely applied. As a result the experience of Lowered ADCP application under the Black Sea conditions is generalized, the algorithms of data processing are given, the profiles of absolute speed of currents are given on the series of stations. It is shown that the proposed approach provides more adequate qualitative and quantitative estimation of the current velocity profile than the known methods do

Timing of acute carotid artery stenting for tandem lesions in patients with acute ischemic stroke:A Maastricht Stroke Quality Registry (MaSQ-Registry) study

BACKGROUND: To better understand the influence of treatment strategies on outcomes for patients with tandem lesions undergoing acute internal carotid artery (ICA) stenting during endovascular treatment (EVT), this study compared clinical, technical, and safety outcomes in patients with acute ischemic stroke due to a large vessel occlusion (LVO) who underwent ICA stenting before versus after intracranial thrombectomy. METHODS: This single-center retrospective cohort study included patients who underwent EVT due to a LVO and periprocedural ICA stenting for significant ICA stenosis or occlusion between September 2020 and January 2023. Data were extracted from the Maastricht Stroke Quality Registry (MaSQ-Registry). Primary outcome was the modified Rankin Scale (mRS) at 3 months. Secondary outcomes included procedure times, number of total thrombectomy attempts, first-attempt excellent recanalization rates (extended Thrombolysis In Cerebral Infarction (eTICI) = 2C after one thrombectomy attempt), and safety outcomes. RESULTS: This study included 50 patients. Thirty-one patients (62%) underwent ICA stenting before intracranial thrombectomy. No significant differences between both groups were found regarding mRS, total procedure time, number of total thrombectomy attempts, first-attempt excellent recanalization, or complications. Time between groin puncture and recanalization (reperfusion time) was significantly longer in patients who had ICA stenting before intracranial thrombectomy versus after intracranial thrombectomy (45 min versus 28 min, P = 0.004). CONCLUSION: ICA stenting after intracranial thrombectomy in patients with tandem lesions undergoing EVT did not lead to better patient outcomes compared to stenting before intracranial thrombectomy, despite shorter reperfusion times

Ischemic Stroke Patients Demonstrate Increased Carotid Plaque Microvasculature Compared to (Ocular) Transient Ischemic Attack Patients

Background: Patients with a recent ischemic stroke have a higher risk of recurrent stroke compared to (ocular) transient ischemic attack (TIA) patients. Plaque microvasculature is considered as a feature of plaque vulnerability and can be quantified with carotid dynamic contrast-enhanced MRI (DCE-MRI). The purpose of this cross-sectional study was to explore the association between plaque microvasculature and the type of recent cerebrovascular events in symptomatic patients with mild-to-moderate carotid stenosis. Methods: A total of 87 symptomatic patients with a recent stroke (n = 35) or (ocular) TIA (n = 52) underwent carotid DCE-MRI examination. Plaque microvasculature was studied in the vessel wall and adventitia using DCEMRI and the pharmacokinetic modeling parameter K trans. Statistical analysis was performed with logistic regression, correcting for associated clinical risk factors. Results: The 75th percentile adventitial (OR 1.97, 95% CI 1.18-3.29) K trans was significantly associated with a recent ischemic stroke compared to (ocular) TIA in multivariate analysis, while clinical risk factors were not significantly associated with the type of event. Conclusions: This study indicates a positive association of leaky plaque microvasculature with a recent ischemic stroke compared to (ocular) TIA. Prospective longitudinal studies are needed to investigate whether Kt rans or other plaque characteristics may serve as an imaging marker for predicting (the type of) future cerebrovascular events. (C) 2017 The Author(s) Published by S. Karger AG, Base

Combined 18F-FDG PET-CT and DCE-MRI to assess inflammation and microvascularization in atherosclerotic plaques

Hallmarks of vulnerable atherosclerotic plaques are inflammation that can be assessed with 18fluorine-fluorodeoxyglucose positron emission tomography/computed tomography, and increased neovascularization that can be evaluated by dynamic contrast-enhanced-MRI. It remains unclear whether these parameters are correlated or represent independent imaging parameters. This study determines whether there is a correlation between inflammation and neovascularization in atherosclerotic carotid plaques. A total of 58 patients with transient ischemic attack or minor stroke in the carotid territory and ipsilateral carotid artery stenosis of 30% to 69% were included. All patients underwent positron emission tomography/computed tomography and dynamic contrast-enhanced-MRI of the carotid plaque. 18Fluorine-fluorodeoxyglucose standard uptake values with target/background ratio were determined. Neovascularization was quantified by the mean (leakage) volume transfer constant Ktrans. Spearman rank correlation coefficients between target/background ratio and Ktrans were calculated. Images suitable for further analysis were obtained in 49 patients. A weak but significant positive correlation between target/background ratio and mean Ktrans (Spearman ρ=0.30 [P=0.035]) and 75th percentile Ktrans (Spearman ρ=0.29 [P=0.041]) was found. There is a weak but significant positive correlation between inflammation on positron emission tomography/computed tomography and neovascularization as assessed with dynamic contrast-enhanced-MRI. Future studies should investigate which imaging modality has the highest predictive value for recurrent stroke, as these are not interchangeable. http://www.clinicaltrials.gov. Unique identifier: NCT0045152

Volumetric measurements (mm³) at baseline and after one year.

<p>Volumetric measurements (mm³) at baseline and after one year.</p

Use of Antiplatelet Agents Is Associated With Intraplaque Hemorrhage on Carotid Magnetic Resonance Imaging : The Plaque at Risk Study

BACKGROUND AND PURPOSE: Intraplaque hemorrhage (IPH), visualized by magnetic resonance imaging, has shown to be associated with the risk of stroke in patients with carotid artery stenosis. The mechanisms of IPH development are poorly understood. In this study, we investigated the association between clinical patient characteristics and carotid IPH on high-resolution magnetic resonance imaging. METHODS: Patients participate in the Plaque at Risk (PARISK) study. This prospective, multicenter cohort study included patients with recent amaurosis fugax, hemispheric transient ischemic attack, or nondisabling stroke in the internal carotid artery territory and an ipsilateral carotid stenosis of <70%, who were not scheduled for carotid revascularization procedure. One hundred patients, recruited between 2010 and 2012, underwent a 3-T high-resolution carotid magnetic resonance imaging. We documented clinical patient characteristics and performed multivariable logistic regression analysis to investigate their association with IPH. RESULTS: IPH was observed in 45 patients (45%) in 1 or both carotid arteries. Male sex and the use of antiplatelet agents before the index event were associated with IPH in univariable analysis. In a multivariable analysis, only previous use of antiplatelet agents was significantly associated with IPH (odds ratio, 2.71; 95% confidence interval, 1.12-6.61). Risk factors of atherosclerotic arterial disease, including a history of symptomatic arterial diseases, were not associated with IPH. CONCLUSIONS: In this cohort of 100 patients with recently symptomatic carotid stenosis, the previous use of antiplatelet agents is associated with carotid IPH on magnetic resonance imaging. Antiplatelet therapy may increase the risk of IPH, but our findings need to be confirmed in larger patient cohorts. The implications for risk stratification remain to be determined

Seven-Tesla Magnetic Resonance Imaging of Atherosclerotic Plaque in the Significantly Stenosed Carotid Artery A Feasibility Study

The objective of this study was to assess the feasibility of carotid vessel wall imaging at 7.0 for T magnetic resonance imaging (MRI) in a series of patients with a symptomatic greater than 70% stenosis of the internal carotid artery.First, a series of 6 healthy volunteers were scanned at 3.0 T and 7.0 T MRI to perform a signal-to-noise ratio comparison between these 2 field strengths. Second, in patients with a greater than 70% stenosed carotid artery, a 7.0 T MRI protocol, consisting of a dual-echo turbo spin echo sequence (echo times of 45 and 150 milliseconds) and a T1-weighted turbo spin echo sequence, was obtained. Lumen and vessel wall were delineated for interobserver and intraobserver reproducibility, and signal intensity distribution in the most severely stenosed part of the internal carotid artery was correlated with different plaque components on histopathologic findings.The mean (SD) signal-to-noise ratio in the vessel wall was 42 (12) at 7.0 T and 24 (4) at 3.0 T. Nineteen patients were included, but technical issues yielded carotid MRI data of 14 patients available for the final analysis. Of these patients, 4 were diagnosed with stroke, 7 were diagnosed with a transient ischemic attack, and 3 were diagnosed with amaurosis fugax. Intraclass correlation coefficient of the agreements of lumen and vessel wall determination between 2 observers and between the repeated measures of 1 observer were above 0.80 in both 3.0 T and 7.0 T data sets of the healthy volunteers and also in the 7.0 T data set of the patients. Signal hyperintensity in the 7.0 T magnetic resonance images was inversely proportional to calcification. Other correlations between plaque components and signal intensity could not be confirmed.This first series of patients with carotid atherosclerotic plaque who were scanned at 7.0 T MRI shows that 7.0 T MRI enables to adequately determine lumen and vessel wall areas. Signal hyperintensity in these 7.0 T magnetic resonance images was inversely proportional to calcification. However, at this stage, no other correlations between histologic findings and vessel wall contrast were found. Implementation of in vivo high-resolution 7.0 T MRI of plaque components for risk stratification remains challenging. Future development of hardware and software is still needed to attain a more robust setup and to enable complete plaque characterization, similar to what is currently possible with multiple MRI sequences at 1.5 T and 3.0 T MRI

Multisequence MR images of a plaque in the internal carotid artery obtained at baseline (upper row) and after one year (bottom row).

<p>The TOF and T2w TSE images at baseline are slightly blurred due to patient motion. There is no obvious change of plaque morphology. There is a plaque with a LRNC and IPH (asterisks) at baseline and at 1-year follow-up. There is a disruption of the FC at both time points (arrows).</p

Microvasculature and intraplaque hemorrhage in atherosclerotic carotid lesions: A cardiovascular magnetic resonance imaging study

Background: The presence of intraplaque haemorrhage (IPH) has been related to plaque rupture, is associated with plaque progression, and predicts cerebrovascular events. However, the mechanisms leading to IPH are not fully understood. The dominant view is that IPH is caused by leakage of erythrocytes from immature microvessels. The aim of the present study was to investigate whether there is an association between atherosclerotic plaque microvasculature and presence of IPH in a relatively large prospective cohort study of patients with symptomatic carotid plaque. Methods: One hundred and thirty-two symptomatic patients with ≥2 mm carotid plaque underwent cardiovascular magnetic resonance (CMR) of the symptomatic carotid plaque for detection of IPH and dynamic contrast-enhanced (DCE)-CMR for assessment of plaque microvasculature. K trans , an indicator of microvascular flow, density and leakiness, was estimated using pharmacokinetic modelling in the vessel wall and adventitia. Statistical analysis was performed using an independent samples T-test and binary logistic regression, correcting for clinical risk factors. Results: A decreased vessel wall K trans was found for IPH positive patients (0.051 ± 0.011 min - 1 versus 0.058 ± 0.017 min - 1 , p = 0.001). No significant difference in adventitial K trans was found in patients with and without IPH (0.057 ± 0.012 min - 1 and 0.057 ± 0.018 min - 1 , respectively). Histological analysis in a subgroup of patients that underwent carotid endarterectomy demonstrated no significant difference in relative microvessel density between plaques without IPH (n = 8) and plaques with IPH (n = 15) (0.000333 ± 0.0000707 vs. and 0.000289 ± 0.0000439, p = 0.585). Conclusions: A reduced vessel wall K trans is found in the presence of IPH. Thus, we did not find a positive association between plaque microvasculature and IPH several weeks after a cerebrovascular event. Not only leaky plaque microvessels, but additional factors may contribute to IPH development. Trial registration: NCT01208025. Registration date September 23, 2010. Retrospectively registered (first inclusion September 21, 2010). NCT01709045, date of registration October 17, 2012. Retrospectively registered (first inclusion August 23, 2011)

No Association between Thrombin Generation and Intra-Plaque Haemorrhage in Symptomatic Carotid Atherosclerotic Plaques: The Plaque at RISK (PARISK) Study

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