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

Integral assessment of the enterprise investment attractiveness: Testing the hypothesis of non-conformity to investor's interests

© Medwell Journals, 2017. The study attempts to improve the construction of a dynamic model for assessing the investment attractiveness of the enterprise. The researchers use the calculation of the Kendall correlation coefficient for two rank series by comparing the actual order of the growth rates of investment appeal indices with the standard ones based on internal environment indicators of a leading chemical enterprise. The researchers calculate the dynamic assessment of investment attractiveness. The study emphasizes that the maximum value of the dynamic assessment of investment attractiveness is equal to one in the case when all observed characteristics conform to the interests of potential investors. To test the null hypothesis about the statistical insignificance of the Kendall correlation coefficient the "tau" statistics and the calculation of the critical values of the Kendall rank correlation coefficient were used. The researchers employed an applied statistical analysis of the company's internal environment indicators for the dynamic assessment of investment attractiveness. In future, this technique will help researchers formulate unified approaches to assessing investment attractiveness by systemizing both internal and external factors based on the structure of the relationships between them

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

Integral assessment of the enterprise investment attractiveness: Testing the hypothesis of non-conformity to investor's interests

© Medwell Journals, 2017. The study attempts to improve the construction of a dynamic model for assessing the investment attractiveness of the enterprise. The researchers use the calculation of the Kendall correlation coefficient for two rank series by comparing the actual order of the growth rates of investment appeal indices with the standard ones based on internal environment indicators of a leading chemical enterprise. The researchers calculate the dynamic assessment of investment attractiveness. The study emphasizes that the maximum value of the dynamic assessment of investment attractiveness is equal to one in the case when all observed characteristics conform to the interests of potential investors. To test the null hypothesis about the statistical insignificance of the Kendall correlation coefficient the "tau" statistics and the calculation of the critical values of the Kendall rank correlation coefficient were used. The researchers employed an applied statistical analysis of the company's internal environment indicators for the dynamic assessment of investment attractiveness. In future, this technique will help researchers formulate unified approaches to assessing investment attractiveness by systemizing both internal and external factors based on the structure of the relationships between them

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