Approaches to classification of microembolic signals in patients recovering from ischemic stroke

Introduction. Microembolus detection by transcranial Doppler (TCD) is the only non-invasive modality for visualization of cerebral embolism. Currently, there is no unified classification of recorded microembolic signals (MES) that could be used in clinical practice. The aim of the study is to investigate biophysical MES parameters in patients with ischemic stroke, as well as to assess approaches to microemboli differentiation by structure and origin to improve the diagnostic accuracy of the method and to reduce the risk of recurrent ischemic events. Materials and methods. The inclusion criterion was TCD-detected signs of MES. We analyzed the data of 28 patients with ischemic stroke (9 women and 19 men; mean age was 58 years 13). We recorded power, duration, and frequency for each MES, and calculated an energy index. Results. A total of 938 MES were reported. In patients with cardioembolic stroke and all other pathogenetic stroke subtypes, biophysical parameter limits were as follows: 14.65 dB for the average power, 9.45 ms for the average duration, and 0.16 J for the average energy index. For patients with atrial fibrillation, characteristic MES power was found to be 13 dB. The MES frequency limit was determined to be 650 Hz for microemboli differentiation by acoustic density. Conclusion. The data obtained can be used to further search for optimal limit ranges for biophysical parameters of various MES in order to establish a single MES classification, which will increase the diagnostic value of microembolus detection by TCD in stroke treatment practice

Магнитно-резонансная томография в оценке цереброваскулярной реактивности

Purpose. To analyze the publications related to the technique of MRI mapping of cerebrovascular reactivity. Materials and methods. We have analyzed 75 publications (4 Russian, 71 foreign), published in the period from 1960 to 2021 years. More than half of these articles were published in the last ten years, with 26 studies – in the period from 2016 to 2021 years.Results. The article systematizes methods for assessing cerebrovascular reactivity and approaches to assessing cerebrovascular reactivity by MRI. The technique of non-enhanced MRI mapping of cerebrovascular reactivity with a hypercapnic challenge is described in detail; alternative vasoactive stimuli are also considered. Issues related to data processing and evaluation of research results were discussed.Conclusion. Impairment of cerebrovascular reactivity plays an important role in the pathogenesis of cerebrovascular diseases. Over the past decades, various radionuclide and ultrasound methods have been widely used to assess cerebrovascular reactivity. In recent years the interest of researchers in MRI as a method of mapping cerebrovascular reactivity has increased significantly. Noninvasiveness, safety, absence of radiation exposure, and good tolerability are the absolute advantages of MRI mapping over other methods of assessing cerebrovascular reactivity. However, the variety of methodological approaches to MRI mapping of cerebrovascular reactivity causes significant variability in the results of the study. Standardization of the procedure should be the first step toward the introduction of MRI mapping of cerebrovascular reactivity into clinical practice.Цель исследования: анализ литературы, касающейся методики проведения МРТ-картирования цереброваскулярной реактивности.Материал и методы. Проанализировано 75 публикаций (4 отечественные, 71 зарубежная), вышедших в свет в период с 1960 по 2021 г. Более половины работ было опубликовано в последнее десятилетие, 26 работ — в период с 2016 по 2021 г.Результаты. В статье систематизированы способы оценки цереброваскулярной реактивности и подходы к оценке цереброваскулярной реактивности методом МРТ. Подробно изложена методика проведения бесконтрастного МРТ-картирования цереброваскулярной реактивности с гиперкапнической пробой; также рассмотрены альтернативные вазоактивные стимулы. Обсуждены вопросы, связанные с обработкой данных и оценкой результатов исследования.Заключение. Нарушения цереброваскулярной реактивности играют важную роль в патогенезе сосудистых заболеваний головного мозга. На протяжении последних десятилетий для оценки цереброваскулярной реактивности широко использовались различные радионуклидные и ультразвуковые методы. В последние годы значительно возрос интерес исследователей к МРТ как методу картирования цереброваскулярной реактивности. Неинвазивность, безопасность, отсутствие лучевой нагрузки и хорошая переносимость являются безусловными преимуществами МРТ-картирования перед другими способами оценки цереброваскулярной реактивности. Однако разнообразие методологических подходов к МРТ-картированию цереброваскулярной реактивности обусловливает значительную вариабельность результатов исследования. Стандартизация процедуры должна являться первым шагом на пути внедрения МРТ-картирования цереброваскулярной реактивности в клиническую практику

Магнитно-резонансная трактография: возможности и ограничения метода, современный подход к обработке данных

Purpose: systematization of the knowledge about diffusion tensor magnetic resonance tomography; analysis of literature related to current limitations of this method and possibilities of overcoming these limitations.Materials and methods. We have analyzed 74 publications (6 Проанализировано 74 публикации (6 Russian, 68 foreign), published in the time period from 1986 to 2021years.  More, than half of these articles were published in the last ten years, 19 studies-in the time period from 2016 to 2021years.Results. In this article we  represent the physical basis of diffusion weighted techniques of magnetic resonance tomography, principles of obtaining diffusion weighted images and diffusion tensor, cover the specific features of the probabilistic and deterministic approaches of the diffusion tensor MRI data processing, describe methods of evaluation of the diffusion characteristics of tissues in clinical practice. Article provides a thorough introduction to the reasons of existing limitations of diffusion tensor MRI and systematization the main developed approaches of overcoming these limitations, such as multi-tensor model, high angular resolution diffusion imaging, diffusion kurtosis visualization. The article consistently reviews the stages of data processing of diffusion tensor magnetic resonance tomography (preprocessing, processing and post processing). We also describe the special aspects of the main approaches to the quantitative data analysis of diffusion tensor magnetic resonance tomography (such as analysis of the region of interest, analysis of the total data amount, quantitative tractography).Conclusion. Magnetic resonance tractography is a unique technique for noninvasive in vivo visualization of brain white matter tracts and assessment of the structural integrity of their constituent axons. In the meantime this technique, which has found applications in numerous pathologies of central nervous system, has a number of significant limitations, and the main of them are the inability to adequately visualize the crossing fibers and the relatively low reproducibility of the results. Standardization of the data postprocessing algorithms, further upgrading of the magnetic resonance scanners and implementation of the alternative tractography methods have the potential of partially reducing of the current limitations.Цель исследования. Систематизация знаний о диффузионной тензорной магнитно-резонансной томографии; анализ литературы, касающейся существующих на сегодняшний момент ограничений метода и возможностей их преодоления.Материал и методы. Проанализировано 74 публикации (6 отечественных, 68 зарубежных), вышедших в свет в период с 1986 по 2021 год. Более половины работ было опубликовано в последнее десятилетие, 19 работ – в период с 2016 по 2021 год.Результаты. В статье изложены физические основы диффузионных методик магнитно-резонансной томографии, принципы получения диффузионно-взвешенных изображений и диффузионного тензора, отражены особенности вероятностного и детерминистского подходов к обработке данных диффузионной тензорной МРТ, а также методы оценки диффузионных характеристик тканей в клинической практике. Подробно рассмотрены причины имеющихся ограничений диффузионной тензорной МРТ, а также систематизированы основные разработанные приемы преодоления этих ограничений, таких как мультитензорная модель, диффузионная визуализация высокого углового разрешения, диффузионная спектральная визуализация, диффузионная куртозисная визуализация. Последовательно рассмотрены этапы обработки данных диффузионной тензорной магнитно-резонансной томографии (препроцессинг, процессинг и постпроцессинг). Отражены особенности основных подходов к количественному анализу данных диффузионной тензорной магнитно-резонансной томографии (таких как анализ области интереса, анализ всего объема данных, количественная трактография).Заключение. Магнитно-резонансная трактография – уникальная методика неинвазивной прижизненной визуализации проводящих путей головного мозга и оценки структурной целостности составляющих их аксонов, нашедшая применение при многих заболеваниях центральной нервной системы. В то же время эта методика имеет ряд существенных ограничений, основными из которых являются невозможность адекватной визуализации перекрещивающихся волокон и относительно низкая воспроизводимость результатов. Стандартизация алгоритмов постпроцессинга данных, дальнейшее совершенствование магнитнорезонансных томографов и внедрение альтернативных методов трактографии потенциально способны частично нивелировать имеющиеся в настоящее время недостатки

Echographic features of the structure of atherosclerotic plaques in carotid ischemic stroke

An assessment of not only the degree of stenosis, but also the structure of atherosclerotic plaques (ASPs) in the carotid arteries can reveal atheromas that are dangerous for the development of cerebrovascular events in asymptomatic individuals.Objective: to study the echostructure of ASPs in patients in the acutest period of carotid ischemic stroke (IS) and to analyze predictors for its development according to ultrasonic duplex scanning (DS).Patients and methods. A study group included the results of DS in 668 patients (370 men and 298 women aged  63±11 and 69±9 years, respectively) with IS in the middle cerebral artery bed. Out of 222 patients, 160 (72.1%), 56 (25.2%), 4 (1.8%), and 2 (0.9%) people had atherothrombotic, cardioembolic, hemodynamic, and lacunar subtypes of IS, respectively. A control group consisted of 903 asymptomatic individuals matched to the patients for gender and age.Results and discussion. In patients with IS, carotid stenoses were characterized by the higher degree of a reduction in the lumen of both the internal carotid arteries (ICA): on the right (r) (53±23%) and left (l) (54±24%) sides, and the common carotid arteries (CCA): on both sides (40±12%) compared to asymptomatic individuals: rICA (40±14%), lICA (39±15%); and both CCAs (32±9%). At the same time, ASPs in the carotid arteries in the acutest period of IS were significantly more frequently homogeneous hypoechoic (21.2%) or heterogeneous with a hypoechoic component (25.6%), and also more frequently had an uneven contour in the rICA (41.3%) and lICA (33.6%), compared to those in asymptomatic individuals (hypoechoicity (7.0 and 5.6%, respectively); the uneven contour was in the rICA (3.2%) and lICA (4.0%). The study indicated that a set of echo signs (the degree of stenosis in the ICA and CCA; the homogeneity and hypoechoicity of ASP in the ICA; the uneven contour of ASP in the carotid arteries) was formed for primary ultrasound carotid stenosis screening carried out using a routine DStechnique. Additional studies that can more accurately identify ASPs that are dangerous for the development of cerebral vascular events are recommended for asymptomatic individuals with ASP and the above signs, which will determine their treatment policy.Conclusion. Atheromas in the carotid arteries in the acutest period of IS are different from those in asymptomatic individuals by a number of features identified during routine ultrasonic DS. The most valuable individual prognostic sign of the development of carotid IS was the uneven contour of ASP in the carotid arteries

Similarities and differences in ultrasound of extracranial brachiocephalic atherosclerotic lesions in patients with ischemic anterior and posterior circulation stroke

Aim. To establish similarities and differences in ultrasound of extracranial brachiocephalic atherosclerotic lesions in patients with ischemic anterior and posterior circulation stroke.Material and methods. The study involved 668 patients (men, 370; women, 298) with carotid territory IS aged 63±11 and 69±9 years, respectively, and 235 patients (men, 129; women, 106) with vertebrobasilar (VB) territory IS aged 59±12 and 63±10 years, respectively, who underwent duplex ultrasound.Results. Atherosclerotic plaques (ASP) in the internal carotid arteries (ICA) were diagnosed significantly more often (p<0,05) (right ICA (ICAr) — 44,0% of cases; left ICA (ICAl) — 48,4%) and the degree of stenosis of ICA mouths was significantly higher (p<0,05) (ICAr —53±23%, ICAl — 54±24%) in carotid territory IS than in VB territory IS (ICAr — 34,0% of cases; average degree of stenosis — 47±18%; ICAl — 33,6%, average degree of stenosis — 46±18%. There were no significant differences in the prevalence of ASP in vertebral arteries and related stenosis in IS in both territories. Also, there were no significant intergroup differences in the prevalence of homogeneous anechoic or hypoechoic and heterogeneous with hypoechoic predominance ASPs in the ICA mouths: in carotid territory IS, such ASPs were detected in each ICA in 33,5% of cases; in VB territory IS, in 29,6% of cases.Conclusion. In patients with carotid and VB territory IS, risky ASPs were recorded with the same frequency, while the overall prevalence of ASPs and the stenosis degree of ICA mouths was significantly higher in carotid IS

Brachiocephalic atherosclerosis in patients with posterior circulation ischemic stroke

Aim. To study echographic and acoustic characteristics of atherosclerotic plaques (ASP) in brachiocephalic arteries (BCA) in patients with acute posterior circulation ischemic stroke (PCIS).Material and methods. In this study we included data of duplex ultrasound from 235 patients (men, 129; women, 106; age, 59±12 and 63±10 years, respectively) with PCIS. Pathogenesis of PCIS was established only in 23 cases: in 17 (74%) — atherothrombosis, in 3 (13%) — cardioembolism, in 3 (13%) — lacunar stroke. Atrial fibrillation was established in 18,5% of patients. A total of 903 asymptomatic individuals were included in the control group, comparable with studied patients by sex and age.Results. The prevalence of ASP in vertebral arteries (VA) was equal in both groups. Also, no significant differences in the degree of VA stenosis were observed. Atherosclerotic lesions of common (CCA) and internal carotid arteries (ICA) on both sides were more often observed in control group, but the degree of their stenosis was higher in PSIS group (р<0,003). In ischemic stroke, stenosis of the right ICA was 47±17%, left ICA — 46±18%, while in asymptomatic individuals, right ICA stenosis was 40±14%, left ICA — 39±15%. In patients with PCIS, ASPs were significantly more often regarded as concentric (22,0% vs 10,4% in PCIS and asymptomatic individuals, respectively), prolonged (24,2% vs 7,5%), homogeneous (41,0% vs 21,1%), as well as were more likely to have an uneven contour (27,7% vs 2,8%).Conclusion. In patients with acute PCIS, the peculiarities of BCA atherosclerosis were recorded, distinguishing it from that in the asymptomatic population

Thrombolytic therapy in patients with ischemic stroke in the vertebrobasilar system

The paper shows the efficiency and safety of increasing the therapeutic window for systemic thrombolysis in verified ischemic stroke in the vertebrobasilar system (VBS), as well as the possibility of effective reperfusion in patients with stenotic occlusive lesions of the basilar artery and clinical signs of severe truncal stroke. Thrombolytic therapy (TLT) over 4.5 hours and in a neurological deficit of >25 scores according to the National Institute of Health (NIHSS) Scale should be performed only within the framework of clinical trials. TLT for stroke in the VBS may substantially alter the approach to rendering care in this pathology and contribute to an increase in the number of patients with a good functional outcome

Синдром Дайка–Давыдова–Массона: описание клинического случая, комплексная диагностика с применением видео-ЭЭГ-мониторинга, МРТ, МР-трактографии и фМРТ

Dyke–Davidoff–Masson syndrome is a possible cause of several pathologies and has rare appearance in clinical practice. One of these causes is a perinatal stroke. The man 59‑year‑old applied to the Federal center of brain and neurotechnologies had this one. The patient had bilateral tonic‑clonic seizures with loss of consciousness, and remission was observed during the last 4 years with antiepileptic drugs treatment. Complex radiological and func‑ tional diagnostics were performed with electroencephalography, magnetic resonance imaging, magnetic resonance tractography, functional magnetic resonance imaging. As a result of research many signs of Dyke–Davidoff–Masson syndrome were found. On the example of damage in the perinatal period and subsequent adaptation of the brain, its plasticity with respect to speech function was shown.Синдром Дайка–Давыдова–Массона является возможным последствием ряда патологий и редко встречается в клинической практике. Одна из его причин – перинатальный инсульт, по поводу последствий которого в ФГБУ «Федеральный центр мозга и нейротехнологий» обратился мужчина 59 лет. У пациента отмечались билатеральные тонико‑клонические приступы с потерей сознания, на фоне лечения антиэпилептическими препаратами в течение последних 4 лет наблюдалась ремиссия. Было проведено комплексное лучевое и функциональное исследование с применением электроэнцефалографии, магнитно‑резонансной томографии, магнитно‑резонансной трактографии, функциональной магнитно‑резонансной томографии. По данным обследования были обнаружены признаки, характерные для синдрома Дайка–Давыдова–Массона. На примере повреждения в перинатальном периоде и последующей адаптации мозга была показана его пластичность в отношении речевой функции