Arterial Spin Labeling Perfusion of the Brain: Emerging Clinical Applications

Arterial spin labeling (ASL) is a magnetic resonance (MR) imaging technique used to assess cerebral blood flow noninvasively by magnetically labeling inflowing blood. In this article, the main labeling techniques, notably pulsed and pseudocontinuous ASL, as well as emerging clinical applications will be reviewed. In dementia, the pattern of hypoperfusion on ASL images closely matches the established patterns of hypometabolism on fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) images due to the close coupling of perfusion and metabolism in the brain. This suggests that ASL might be considered as an alternative for FDG, reserving PET to be used for the molecular disease-specific amyloid and tau tracers. In stroke, ASL can be used to assess perfusion alterations both in the acute and the chronic phase. In arteriovenous malformations and dural arteriovenous fistulas, ASL is very sensitive to detect even small degrees of shunting. In epilepsy, ASL can be used to assess the epileptogenic focus, both in peri- and interictal period. In neoplasms, ASL is of particular interest in cases in which gadolinium-based perfusion is contraindicated (eg, allergy, renal impairment) and holds promise in differentiating tumor progression from benign causes of enhancement. Finally, various neurologic and psychiatric diseases including mild traumatic brain injury or posttraumatic stress disorder display alterations on ASL images in the absence of visualized structural changes. In the final part, current limitations and future developments of ASL techniques to improve clinical applicability, such as multiple inversion time ASL sequences to assess alterations of transit time, reproducibility and quantification of cerebral blood flow, and to measure cerebrovascular reserve, will be reviewed

Assessment of hot gas contaminant control

The objective of this work is to gather data and information to assist DOE in responding to the NRC recommendation on hot gas cleanup by performing a comprehensive assessment of hot gas cleanup systems for advanced coal-based Integrated Gasification Combined Cycle (IGCC) and Pressurized Fluidized Bed Combustion (PFBC) including the status of development of the components of the hot gas cleanup systems, and the probable cost and performance impacts. The scope and time frame of information gathering is generally responsive to the boundaries set by the National Research council (NRC), but includes a broad range of interests and programs which cover hot gas cleanup through the year 2010. As the status of hot gas cleanup is continually changing, additional current data and information are being obtained for this effort from this 1996 METC Contractors` Review Meeting as well as from the 1996 Pittsburgh Coal Conference, and the University of Karlsruhe Symposium. The technical approach to completing this work consists of: (1) Determination of the status of hot gas cleanup technologies-- particulate collection systems, hot gas desulfurization systems, and trace contaminant removal systems; (2) Determination of hot gas cleanup systems cost and performance sensitivities. Analysis of conceptual IGCC and PFBC plant designs with hot gas cleanup have been performed. The impact of variations in hot gas cleanup technologies on cost and performance was evaluated using parametric analysis of the baseline plant designs and performance sensitivity

Non-inferiority of Deep Learning Model to Segment Acute Stroke on Non-contrast CT Compared to Neuroradiologists

Purpose: To develop a deep learning model to segment the acute ischemic infarct on non-contrast Computed Tomography (NCCT). Materials and Methods In this retrospective study, 227 Head NCCT examinations from 200 patients enrolled in the multicenter DEFUSE 3 trial were included. Three experienced neuroradiologists (experts A, B and C) independently segmented the acute infarct on each study. The dataset was randomly split into 5 folds with training and validation cases. A 3D deep Convolutional Neural Network (CNN) architecture was optimized for the data set properties and task needs. The input to the model was the NCCT and the output was a segmentation mask. The model was trained and optimized on expert A. The outcome was assessed by a set of volume, overlap and distance metrics. The predicted segmentations of the best model and expert A were compared to experts B and C. Then we used a paired Wilcoxon signed-rank test in a one-sided test procedure for all metrics to test for non-inferiority in terms of bias and precision. Results: The best performing model reached a Surface Dice at Tolerance (SDT)5mm of 0.68 \pm 0.04. The predictions were non-inferior when compared to independent experts in terms of bias and precision (paired one-sided test procedure for differences in medians and bootstrapped standard deviations with non-inferior boundaries of -0.05, 2ml, and 2mm, p < 0.05, n=200). Conclusion: For the segmentation of acute ischemic stroke on NCCT, our 3D CNN trained with the annotations of one neuroradiologist is non-inferior when compared to two independent neuroradiologists

Predicting Infarct Core From Computed Tomography Perfusion in Acute Ischemia With Machine Learning: Lessons From the ISLES Challenge.

BACKGROUND AND PURPOSE The ISLES challenge (Ischemic Stroke Lesion Segmentation) enables globally diverse teams to compete to develop advanced tools for stroke lesion analysis with machine learning. Detection of irreversibly damaged tissue on computed tomography perfusion (CTP) is often necessary to determine eligibility for late-time-window thrombectomy. Therefore, the aim of ISLES-2018 was to segment infarcted tissue on CTP based on diffusion-weighted imaging as a reference standard. METHODS The data, from 4 centers, consisted of 103 cases of acute anterior circulation large artery occlusion stroke who underwent diffusion-weighted imaging rapidly after CTP. Diffusion-weighted imaging lesion segmentation was performed manually and acted as a reference standard. The data were separated into 63 cases for training and 40 for testing, upon which quality metrics (dice score coefficient, Hausdorff distance, absolute lesion volume difference, etc) were computed to rank methods based on their overall performance. RESULTS Twenty-four different teams participated in the challenge. Median time to CTP was 185 minutes (interquartile range, 180-238), the time between CTP and magnetic resonance imaging was 36 minutes (interquartile range, 25-79), and the median infarct lesion size was 15.2 mL (interquartile range, 5.7-45). The best performance for Dice score coefficient and absolute volume difference were 0.51 and 10.1 mL, respectively, from different teams. Based on the ranking criteria, the top team's algorithm demonstrated for average Dice score coefficient and average absolute volume difference 0.51 and 10.2 mL, respectively, outperforming the conventional threshold-based method (dice score coefficient, 0.3; volume difference, 15.3). Diverse algorithms were used, almost all based on deep learning, with top-ranked approaches making use of the raw perfusion data as well as methods to synthetically generate complementary information to boost prediction performance. CONCLUSIONS Machine learning methods may predict infarcted tissue from CTP with improved accuracy compared with threshold-based methods used in clinical routine. This dataset will remain public and can be used to test improvement in algorithms over time

Comparative overwiew of brain perfusion imaging techniques

Background and Purpose - Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are positron emission tomography, single photon emission computed tomography, Xenon-enhanced computed tomography, dynamic perfusion computed tomography, MRI dynamic susceptibility contrast, arterial spin labeling, and Doppler ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow or cerebral blood volume. All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks. Summary of Review - This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview established by consensus among specialists of the various techniques. Conclusions - For clinicians, this article should offer a clearer picture of the pros and cons of currently available brain perfusion imaging techniques and assist them in choosing the proper method for every specific clinical setting

Comparative overview of brain perfusion imaging techniques Epub

Background and Purpose - Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are positron emission tomography, single photon emission computed tomography, Xenon-enhanced computed tomography, dynamic perfusion computed tomography, MRI dynamic susceptibility contrast, arterial spin labeling, and Doppler ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow or cerebral blood volume. All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks. Summary of Review - This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview established by consensus among specialists of the various techniques. Conclusions - For clinicians, this article should offer a clearer picture of the pros and cons of currently available brain perfusion imaging techniques and assist them in choosing the proper method for every specific clinical setting

Вплив L-aргініну на швидкість розрішення післяопераційного парезу кишечника у хворих з ургентною абдомінальною патологією

Background. Postoperative ileus is widespread in the postoperative period and occurs not only after extended operations on the abdominal cavity, retroperitoneal cavity, but also after minor surgical interventions, including laparoscopic operations [1, 2]. The aim of this study is to increase the effectiveness of intensive care after urgent abdominal surgeries by developing a drug correction for bowel motility disorders based on studying of the motor and evacuator function of the gastrointestinal tract, inflammatory markers, hemodynamic parameters and electrolyte blood composition. Materials and methods. 51 patients were examined, who underwent urgent surgical interventions with laparotomy access for infringed hernias, acute intestinal obstruction, perforation of duodenal ulcers. Depending on the variant of drug correction of postoperative intestinal motility disorder, patients were divided into 2 groups. The first (control) group (n = 27). In the postoperative period, the pharmacological correction of the motor-evacuator function of the gastrointestinal tract was performed by combining a solution of 0,5% metoclopramide and neostigmine bromide. The second (main) group (n = 24). In the postoperative period, the pharmacological correction of the motor-evacuator function of the gastrointestinal tract was performed by combining 0.5% metoclopramide solution and L-arginine (Tivortin, Yuriya-Farm, Ukraine). Motorevacuation disorders of the gastrointestinal tract (the frequency of development of bloating, nausea, vomiting, delay in the escape of gases, an independent moving of gases, measurement of intra-abdominal pressure), parameters of hemodynamics, the level of systolic, diastolic, mean arterial pressure, cardiac index, stroke volume, total peripheral vascular resistance, heart rate, minute volume of blood circulation and left ventricular power, markers of inflammation (leukocyte count, fibrinogen, IL-lα, TNFα, IL-10, calculation of leukocyte intoxication index, the study of electrolytes of blood serum (Na+, K+, Ca2+, Cl- ) were studied before and after 1st, 3rd and 7th days after the operation. Results. The use of L-arginine leads to a decrease in the phenomena of peripheral vasospasm, which, improving the microcirculation of the intestinal wall leads to a faster recovery of the motor-evacuation function of the gastrointestinal tract. With standard prokinetic therapy (combination of metoclopramide with neostigmine bromide), the number of patients with elevated intra-abdominal pressure increases in 92,1%, оn the second day after surgery, the number of patients with elevated intra-abdominal pressure exceeds the norm in 100%. The resumption of intestinal motility 3 days after the operation is accompanied by the normalization of intra-abdominal pressure in 55% of patients. Against the backdrop of the use of L-arginine with metoclopramide on day 1 after the operation, the number of patients with an increase in intra-abdominal pressure does not exceed 50%. 37,5% of them have elevated intra-abdominal pressure, 8,3% have abdominal hypertension of the 1st degree. On the second day of the observation, intraabdominal pressure in 41,7% patients normalized, abdominal hypertension of 1 degree was noted in 16,7%. of them. On the 3rd day after surgery, intra-abdominal pressure corresponded to the norm in 79,2% of patients, abdominal hypertension of 1st degree was registered in 8,3% of patients. Сonclusions. The use of a combination of metoclopramide with L-arginine reduces the stress on the myocardium, activates - anti-inflammatory link of the cytokine system, accelerates the normalization of intra-abdominal pressure, increases the rate of self-evacuation, independent defecation, and reduces the patients’ stay in the intensive care, which makes it possible to recommend it as the most optimal remedy for resuming motor activity intestines after urgent operations in abdominal surgery.Актуальность. Моторно-эвакуаторная дисфункция желудочно-кишечного тракта широко распространена в послеоперационном периоде и возникает не только после больших операций на брюшной полости, забрюшинном пространстве, но и после небольших по объему оперативных вмешательств, в том числе выполненных лапароскопически [1, 2]. Целью данного исследования является повышение эффективности интенсивной терапии после неотложных абдоминальных операций путем разработки медикаментозной коррекции нарушений моторики кишечника на основании изучения моторно-эвакуаторной функции желудочно-кишечного тракта, маркеров воспаления, показателей гемодинамики и электролитного состава крови. Материалы и методы. Обследовано 51 больных, которым проводились ургентные оперативные вмешательства лапаротомным доступом по поводу ущемленнных грыж, острой кишечной непроходимости, перфорации язв двенадцатиперстной кишки. В зависимости от варианта медикаментозной коррекции послеоперационного нарушения моторики кишечника пациенты были разделены на 2 группы. У больных первой (контрольной) группы (n=27) в послеоперационном периоде медикаментозная коррекция моторно-эвакуаторной функции желудочно-кишечного тракта проводилась комбинацией раствора метоклопрамида и неостигмина бромида. Больным второй (основной) группы (n = 24) в послеоперационном периоде медикаментозная коррекция моторно-эвакуаторной функции желудочно-кишечного тракта проводилась комбинацией раствора метоклопрамида и L-аргинина (Тивортин, “Юрия-Фарм”, Украина). Моторно-эвакуаторные нарушения желудочно-кишечного тракта (частоту развития вздутия живота, тошноту, рвоту, задержку отхождения газов, начало самостоятельного отхождения газов, измерение внутрибрюшного давления), параметры гемодинамики, уровень систолического, диастолического, среднего артериального давления, сердечный индекс, ударный объем, общее периферическое сосудистое сопротивление, частоту сердечных сокращений, минутный объем кровообращения, работу имощность левого желудочка, маркеры воспаления (уровень лейкоцитов, фибриногена, IL-lα, TNFα, IL-10, лейкоцитарный индекс интоксикации, уровень электролитов сыворотки крови (Na+ , K+ , Ca2+, Cl- ) изучали до и на 1, 3, 5 и 7 сутки после операции. Результаты. Применение L-аргинина уменьшало явления периферического вазоспазма, что за счёт улучшения микроциркуляции стенки кишки способствовало ускоренному восстановлению моторно-эвакуаторной функции желудочно-кишечного тракта. При стандартной прокинетической терапии (комбинация метоклопрамида с неостигмина бромидом) через 1 сутки после операции до 92,1% увеличивается количество больных с повышенным внутрибрюшным давлением, на 2 сутки после операции количество больных с повышенным внутрибрюшным давлением увеличивается до 100%. Возобновление моторики кишечника через 3 суток после операции сопровождается нормализацией внутрибрюшного давления у 55% больных. На фоне применения L-аргинина с метоклопрамидом в 1 сутки после операции количество больных с повышенным внутрибрюшым давлением не превышает 50%, из них 37,5% имеют повышенное внутрибрюшное давление, 8,3% – внутрибрюшную гипертензию 1 степени. На вторые сутки наблюдения у 41,7% больных внутрибрюшное давление нормализуется, внутрибрюшная гипертензия 1 степени отмечается у 16,7%. На 3 сутки после операции внутрибрюшное давление соответствует норме у 79,2% больных, внутрибрюшная гипертензия 1 степени регистрируется у 8,3% больных. Выводы. Использование комбинации метоклопрамида с L-аргинином уменьшает нагрузку на миокард, активизирует противовоспалительное звено цитокиновой системы, ускоряет нормализацию внутрибрюшного давления, увеличивает скорость самостоятельного отхождения газов и дефекации, сокращает пребывание пациентов в ОАИТ, что позволяет рекомендовать его в качестве наиболее оптимального варианта возобновления моторики кишечника после неотложных операций в абдоминальной хирургии.Актуальність.&nbsp;Моторно-евакуаторна дисфункція шлунково-кишкового тракту широко розповсюджена в післяопераційному періоді і виникає не тільки після великих операцій на черевній порожнині, заочеревиннному просторі, а й після невеликих за обсягом оперативних втручань, у тому числі виконаних лапароскопічно. Порушення моторики шлунка та кишечника зазвичай триває перші 3–5 діб після операції, що підвищує тривалість перебування в стаціонарі, летальність та вартість лікування [1, 2]. Мета дослідження.&nbsp;Підвищення ефективності інтенсивної терапії після невідкладних абдомінальних операцій шляхом розробки та обґрунтування медикаментозної корекції порушень моторики кишок на підставі вивчення моторно-евакуаторної функції шлунково-кишкового тракту, маркерів запалення, показників гемодинаміки та електролітного складу крові. Матеріали та методи.&nbsp;Обстежено 51 хворих, яким у КЗ “Дніпропетровська шоста міська клінічна лікарня” ДОР проводилися оперативні втручання лапаротомним доступом з приводу защемлених кил, гострої кишкової непрохідності, перфорації виразок 12-палої кишки з розлитим перитонітом. Залежно від варіанта медикаментозної корекції післяопераційного порушення моторики кишок хворих було поділено на дві групи. До 1 (контрольної) групи увійшло 27 пацієнтів. Тривалість оперативного втручання у хворих цієї групи становила 81,5 ± 29,0 хвилин. Медикаментозна корекція порушень моторно-евакуаторної функції шлунково-кишкового тракту у них проводилася комбінацією метоклопраміду та неостигміну броміду. До 2 (основної) групи увійшло 24 хворих, серед яких було 9 чоловіків і 15 жінок. Тривалість оперативного втручання складала 104,6 ± 48,3 хвилини. Хворим цієї групи медикаментозна корекція моторно-евакуаторної функції шлунково-кишкового тракту проводилася комбінацією розчину 0,5 % метоклопраміду та L-аргініну (Тівортін, “Юрія-Фарм”, Україна). Моторно-евакуаторні порушення шлунково-кишкового тракту, вимірювання внутрішньочеревного тиску, параметрів гемодинаміки, маркерів запалення здійстнювали до операції, через 1, 3 і 7 діб після неї. Прикінцевими результатами лікування були: тривалість перебування у BAIT та у стаціонарі, летальність у BAIT та у стаціонарі, строки відновлення самостійного відходження газів та відновлення самостійної дефекації. Кінцевою точкою дослідження була 28 доба після оперативного втручання, коли оцінювали якість життя за шкалою Rancho Los Amigos Scale (RLAS). Результати. До операції гострі хірургічні захворювання органів черевної порожнини супроводжуються моторно-евакуаторними розладами шлунково-кишкового тракту, помірною внутрішньочеревною гіпертензією, гемодинамічними змінами у вигляді підвищення роботи лівого шлуночка при зменшенні його потужності, збільшенням периферичного судинного опору на тлі зменшення ударного об’єму. В післяопераційному періоді стандартної стимуляції шлунково-кишкового тракту у більшості хворих порушення моторики шлунково-кишкового тракту досягають свого максимуму на 2–3 добу та супроводжуються підвищенням внутрішньочеревного тиску, наростаючим збільшенням судинного опору, підвищеною роботою лівого шлуночка при зменшеній його потужності та запальною відповіддю організму, яка зберігається понад 7 діб після операції. Прискорення відновлення перистальтики настає при включенні до терапії L-аргініну і супроводжується зменшенням постнавантаження, сталою роботою лівого шлуночка при збільшенні його потужності та прискореним розрішенням запальної відповіді організму

Contralateral Hemispheric Cerebral Blood Flow Measured With Arterial Spin Labeling Can Predict Outcome in Acute Stroke.

Background and Purpose- Imaging is frequently used to select acute stroke patients for intra-arterial therapy. Quantitative cerebral blood flow can be measured noninvasively with arterial spin labeling magnetic resonance imaging. Cerebral blood flow levels in the contralateral (unaffected) hemisphere may affect capacity for collateral flow and patient outcome. The goal of this study was to determine whether higher contralateral cerebral blood flow (cCBF) in acute stroke identifies patients with better 90-day functional outcome. Methods- Patients were part of the prospective, multicenter iCAS study (Imaging Collaterals in Acute Stroke) between 2013 and 2017. Consecutive patients were enrolled after being diagnosed with anterior circulation acute ischemic stroke. Inclusion criteria were ischemic anterior circulation stroke, baseline National Institutes of Health Stroke Scale score ≥1, prestroke modified Rankin Scale score ≤2, onset-to-imaging time &lt;24 hours, with imaging including diffusion-weighted imaging and arterial spin labeling. Patients were dichotomized into high and low cCBF groups based on median cCBF. Outcomes were assessed by day-1 and day-5 National Institutes of Health Stroke Scale; and day-30 and day-90 modified Rankin Scale. Multivariable logistic regression was used to test whether cCBF predicted good neurological outcome (modified Rankin Scale score, 0-2) at 90 days. Results- Seventy-seven patients (41 women) met the inclusion criteria with median (interquartile range) age of 66 (55-76) yrs, onset-to-imaging time of 4.8 (3.6-7.7) hours, and baseline National Institutes of Health Stroke Scale score of 13 (9-20). Median cCBF was 38.9 (31.2-44.5) mL per 100 g/min. Higher cCBF predicted good outcome at day 90 (odds ratio, 4.6 [95% CI, 1.4-14.7]; P=0.01), after controlling for baseline National Institutes of Health Stroke Scale, diffusion-weighted imaging lesion volume, and intra-arterial therapy. Conclusions- Higher quantitative cCBF at baseline is a significant predictor of good neurological outcome at day 90. cCBF levels may inform decisions regarding stroke triage, treatment of acute stroke, and general outcome prognosis. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT02225730

Neuroimaging Evidence of Major Morpho-Anatomical and Functional Abnormalities in the BTBR T+TF/J Mouse Model of Autism

BTBR T+tf/J (BTBR) mice display prominent behavioural deficits analogous to the defining symptoms of autism, a feature that has prompted a widespread use of the model in preclinical autism research. Because neuro-behavioural traits are described with respect to reference populations, multiple investigators have examined and described the behaviour of BTBR mice against that exhibited by C57BL/6J (B6), a mouse line characterised by high sociability and low self-grooming. In an attempt to probe the translational relevance of this comparison for autism research, we used Magnetic Resonance Imaging (MRI) to map in both strain multiple morpho-anatomical and functional neuroimaging readouts that have been extensively used in patient populations. Diffusion tensor tractography confirmed previous reports of callosal agenesis and lack of hippocampal commissure in BTBR mice, and revealed a concomitant rostro-caudal reorganisation of major cortical white matter bundles. Intact inter-hemispheric tracts were found in the anterior commissure, ventro-medial thalamus, and in a strain-specific white matter formation located above the third ventricle. BTBR also exhibited decreased fronto-cortical, occipital and thalamic gray matter volume and widespread reductions in cortical thickness with respect to control B6 mice. Foci of increased gray matter volume and thickness were observed in the medial prefrontal and insular cortex. Mapping of resting-state brain activity using cerebral blood volume weighted fMRI revealed reduced cortico-thalamic function together with foci of increased activity in the hypothalamus and dorsal hippocampus of BTBR mice. Collectively, our results show pronounced functional and structural abnormalities in the brain of BTBR mice with respect to control B6 mice. The large and widespread white and gray matter abnormalities observed do not appear to be representative of the neuroanatomical alterations typically observed in autistic patients. The presence of reduced fronto-cortical metabolism is of potential translational relevance, as this feature recapitulates previously-reported clinical observations