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cerebral hemodynamics

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https://www.readbyqxmd.com/read/27913820/cerebral-blood-flow-transit-time-and-apparent-diffusion-coefficient-in-moyamoya-disease-before-and-after-acetazolamide
#1
Christian Federau, Soren Christensen, Zungho Zun, Sun-Won Park, Wendy Ni, Michael Moseley, Greg Zaharchuk
INTRODUCTION: The goal of this study was to assess the changes in arterial spin labeling (ASL) cerebral blood flow (CBF) and arterial transit time (ATT), and in apparent diffusion coefficient (ADC), before and after an acetazolamide challenge in moyamoya patients, as function of arterial stenosis severity. METHODS: Pre-operative patients diagnosed with moyamoya disease who could undergo MRI at 3.0T were recruited for this study. A multi-delay pseudo-continuous ASL and a diffusion-weighted sequence were acquired before and 15 min after acetazolamide injection...
December 2, 2016: Neuroradiology
https://www.readbyqxmd.com/read/27912253/sex-and-age-differences-in-epinephrine-mechanisms-and-outcomes-after-brain-injury
#2
William M Armstead, John Riley, Monica S Vavilala
Traumatic brain injury (TBI) is the leading cause of injury related death in children, with boys and children under 4 years having particularly poor outcomes. Cerebral autoregulation is often impaired after TBI, contributing to poor outcome. Cerebral perfusion pressure can be normalized by use of vasoactive agents. The c-Jun-terminal kinase (JNK) isoform of mitogen activated protein kinase (MAPK) produces hemodynamic impairment after TBI, but less is known about its role in histopathology. We investigated whether epinephrine (EPI) age and sex dependently protected cerebral autoregulation and limited histopathology after TBI and the role of JNK in that outcome...
December 2, 2016: Journal of Neurotrauma
https://www.readbyqxmd.com/read/27911329/comparison-of-model-based-indices-of%C3%A2-cerebral-autoregulation-and-vasomotor-reactivity-using-transcranial-doppler-versus-near-infrared-spectroscopy-in%C3%A2-patients-with-amnestic-mild-cognitive-impairment
#3
Vasilis Z Marmarelis, Dae C Shin, Takashi Tarumi, Rong Zhang
We recently introduced model-based "physiomarkers" of dynamic cerebral autoregulation and CO2 vasomotor reactivity as an aid for diagnosis of early-stage Alzheimer's disease (AD) [1], where significant impairment of dynamic vasomotor reactivity (DVR) was observed in early-stage AD patients relative to age-matched controls. Milder impairment of DVR was shown in patients with amnestic mild cognitive impairment (MCI) using the same approach in a subsequent study [2]. The advocated approach utilizes subject-specific data-based models of cerebral hemodynamics to quantify the dynamic effects of resting-state changes in arterial blood pressure and end-tidal CO2 (the putative inputs) upon cerebral blood flow velocity (the putative output) measured at the middle cerebral artery via transcranial Doppler (TCD)...
November 28, 2016: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/27909839/biventricular-support-using-a-centrifugal-pump-in-a-6%C3%A2-year-old-with-fulminant-myocarditis
#4
Hiromu Kehara, Tamaki Takano, Takamitsu Terasaki, Kenji Okada
We experienced a case of ventricular assist with both a pulsatile-flow and a continuous-flow pump in a pediatric patient, and herein report the clinical course and characteristics of the pumps. A 6-year-old female was diagnosed with fulminant myocarditis and transferred to our hospital for mechanical support. After 12 days of extracorporeal membrane oxygenation, we implanted a left ventricular assist device (LVAD) and a right ventricular assist device (RVAD) using centrifugal Gyro pumps with a membrane oxygenator in a paracorporeal fashion...
December 1, 2016: Journal of Artificial Organs: the Official Journal of the Japanese Society for Artificial Organs
https://www.readbyqxmd.com/read/27909403/cortical-sensorimotor-processing-of-painful-pressure-in-patients-with-chronic-lower-back-pain-an-optical-neuroimaging-study-using-fnirs
#5
Andrea Vrana, Michael L Meier, Sabina Hotz-Boendermaker, Barry K Humphreys, Felix Scholkmann
In this study we investigated sensorimotor processing of painful pressure stimulation on the lower back of patients with chronic lower back pain (CLBP) by using functional near-infrared spectroscopy (fNIRS) to measure changes in cerebral hemodynamics and oxygenation. The main objectives were whether patients with CLBP show different relative changes in oxy- and deoxyhemoglobin ([O2Hb] and [HHb]) in the supplementary motor area (SMA) and primary somatosensory cortex (S1) compared to healthy controls (HC). Twelve patients with CLBP (32 ± 6...
2016: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/27908788/time-to-wake-up-studying-neurovascular-coupling-and-brain-wide-circuit-function-in-the-un-anesthetized-animal
#6
REVIEW
Yu-Rong Gao, Yuncong Ma, Qingguang Zhang, Aaron T Winder, Zhifeng Liang, Lilith Antinori, Patrick J Drew, Nanyin Zhang
Functional magnetic resonance imaging (fMRI) has allowed the noninvasive study of task-based and resting-state brain dynamics in humans by inferring neural activity from blood-oxygenation-level dependent (BOLD) signal changes. An accurate interpretation of the hemodynamic changes that underlie fMRI signals depends on the understanding of the quantitative relationship between changes in neural activity and changes in cerebral blood flow, oxygenation and volume. While there has been extensive study of neurovascular coupling in anesthetized animal models, anesthesia causes large disruptions of brain metabolism, neural responsiveness and cardiovascular function...
November 28, 2016: NeuroImage
https://www.readbyqxmd.com/read/27908148/local-attenuation-curve-optimization-framework-for-high-quality-perfusion-maps-in-low-dose-cerebral-perfusion-ct
#7
Vincent Van Nieuwenhove, Geert Van Eyndhoven, K Joost Batenburg, Nico Buls, Jef Vandemeulebroucke, Jan De Beenhouwer, Jan Sijbers
PURPOSE: Cerebral perfusion x-ray computed tomography (PCT) is a powerful tool for noninvasive imaging of hemodynamic information throughout the brain. Conventional PCT requires the brain to be imaged multiple times during the perfusion process, and hence radiation dose is a major concern. The authors propose a PCT reconstruction algorithm that allows for lowering the dose while maintaining a high quality of the perfusion maps. It relies on an accurate estimation of the arterial input function (AIF), which in turn depends on the quality of the attenuation curves in the arterial region...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27906765/hemodynamic-disturbances-in-the-early-phase-after-subarachnoid-hemorrhage-regional-cerebral-blood-flow-studied-by-bedside-xenon-enhanced-ct
#8
Henrik Engquist, Anders Lewén, Tim Howells, Ulf Johnson, Elisabeth Ronne-Engström, Pelle Nilsson, Per Enblad, Elham Rostami
BACKGROUND: The mechanisms leading to neurological deterioration and the devastating course of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) are still not well understood. Bedside xenon-enhanced computerized tomography (XeCT) enables measurements of regional cerebral blood flow (rCBF) during neurosurgical intensive care. In the present study, CBF characteristics in the early phase after severe SAH were explored and related to clinical characteristics and early clinical course outcome...
November 30, 2016: Journal of Neurosurgical Anesthesiology
https://www.readbyqxmd.com/read/27903339/-effect-of-goal-directed-haemodynamic-management-on-the-postoperative-outcome-in-elderly-patients-with-fragile-cardiac-function-undergoing-abdominal-surgery
#9
L S Zheng, E W Gu, X H Peng, L Zhang, Y Y Cao
Objective: To investigate the effect of goal-directed haemodynamic management based on stroke volume variation (SVV), cardiac index (CI) and mean arterial blood pressure (MAP) on the postoperative outcome in elderly patients with fragile cardiac function undergoing gastrointestinal surgery. Methods: Ninety patients with fragile cardiac function, aged 65-90 years old, ASAⅡ or Ⅲ, NYHA Ⅱor Ⅲ, scheduled for abdominal surgery were enrolled in this study.The patients were randomly assigned to two groups: Experience anesthesia group (group E, n=45) and goal-directed hemodynamic management group (G group, n=45)...
November 22, 2016: Zhonghua Yi Xue za Zhi [Chinese medical journal]
https://www.readbyqxmd.com/read/27902858/reliable-estimation-of-microvascular-flow-patterns-in-patients-with-disrupted-blood-brain-barrier-using-dynamic-susceptibility-contrast-mri
#10
Mikkel Bo Hansen, Anna Tietze, Jayashree Kalpathy-Cramer, Elizabeth R Gerstner, Tracy T Batchelor, Leif Østergaard, Kim Mouridsen
PURPOSE: To present and quantify the performance of a method to compute tissue hemodynamic parameters from dynamic susceptibility contrast (DSC) MRI data in brain tissue with possible nonintact blood-brain barrier. THEORY AND MATERIALS AND METHODS: We propose a Bayesian scheme to obtain perfusion metrics, including capillary transit-time heterogeneity (CTH), from DSC-MRI data in the presence of contrast agent extravasation. Initial performance assessment is performed through simulations...
November 30, 2016: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/27894675/the-manifestation-of-vortical-and-secondary-flow-in-the-cerebral-venous-outflow-tract-an-in-vivo-mr-velocimetry-study
#11
Sarah Kefayati, Matthew Amans, Farshid Faraji, Megan Ballweber, Evan Kao, Sinyeob Ahn, Karl Meisel, Van Halbach, David Saloner
Aberrations in flow in the cerebral venous outflow tract (CVOT) have been implicated as the cause of several pathologic conditions including idiopathic intracranial hypertension (IIH), multiple sclerosis (MS), and pulsatile tinnitus (PT). The advent of 4D flow magnetic resonance imaging (4D-flow MRI) has recently allowed researchers to evaluate blood flow patterns in the arterial structures with great success. We utilized similar imaging techniques and found several distinct flow characteristics in the CVOT of subjects with and without lumenal irregularities...
November 15, 2016: Journal of Biomechanics
https://www.readbyqxmd.com/read/27891172/vortex-analysis-of-intra-aneurismal-flow-in-cerebral-aneurysms
#12
Kevin Sunderland, Christopher Haferman, Gouthami Chintalapani, Jingfeng Jiang
This study aims to develop an alternative vortex analysis method by measuring structure ofIntracranial aneurysm (IA) flow vortexes across the cardiac cycle, to quantify temporal stability of aneurismal flow. Hemodynamics were modeled in "patient-specific" geometries, using computational fluid dynamics (CFD) simulations. Modified versions of known λ2 and Q-criterion methods identified vortex regions; then regions were segmented out using the classical marching cube algorithm. Temporal stability was measured by the degree of vortex overlap (DVO) at each step of a cardiac cycle against a cycle-averaged vortex and by the change in number of cores over the cycle...
2016: Computational and Mathematical Methods in Medicine
https://www.readbyqxmd.com/read/27882440/hemodynamic-changes-in-a-middle-cerebral-artery-aneurysm-at-follow-up-times-before-and-after-its-rupture-a-case-report-and-a-review-of-the-literature
#13
A Sejkorová, K D Dennis, H Švihlová, O Petr, G Lanzino, A Hejčl, D Dragomir-Daescu
Hemodynamic parameters play a significant role in the development of cerebral aneurysms. Parameters such as wall shear stress (WSS) or velocity could change in time and may contribute to aneurysm growth and rupture. However, the hemodynamic changes at the rupture location remain unclear because it is difficult to obtain data prior to rupture. We analyzed a case of a ruptured middle cerebral artery (MCA) aneurysm for which we acquired imaging data at three time points, including at rupture. A patient with an observed MCA aneurysm was admitted to the emergency department with clinical symptoms of a subarachnoid hemorrhage...
November 24, 2016: Neurosurgical Review
https://www.readbyqxmd.com/read/27882094/the-protective-and-hemodynamic-effects-of-dexmedetomidine-on-hypertensive-cerebral-hemorrhage-patients-in-the-perioperative-period
#14
Junhui Zhao, Chuixian Zhou
The aim of the present study was to analyze the protective and hemodynamic effects of dexmedetomidine in hypertensive cerebral hemorrhage (HCH) patients during perioperative period. In total, 50 HCH patients were selected and randomly divided into two groups, one group was administered with dexmedetomidine and the other groups with midazolam. The mean arterial pressure (MAP), heart rate (HR) and blood oxygen saturation (SpO2) were monitored in the two groups of patients before and during the operation. The MAP, HR, SpO2 and PETCO2 recorded 5 min after admission into the operation room was considered T1, the same parameters recorded 10 min after drug administration were considered T2, just after starting the operation were considered T3 and 30 min after start of operation were considered T4...
November 2016: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/27877133/decomposition-of-near-infrared-spectroscopy-signals-using-oblique-subspace-projections-applications-in-brain-hemodynamic-monitoring
#15
Alexander Caicedo, Carolina Varon, Borbala Hunyadi, Maria Papademetriou, Ilias Tachtsidis, Sabine Van Huffel
Clinical data is comprised by a large number of synchronously collected biomedical signals that are measured at different locations. Deciphering the interrelationships of these signals can yield important information about their dependence providing some useful clinical diagnostic data. For instance, by computing the coupling between Near-Infrared Spectroscopy signals (NIRS) and systemic variables the status of the hemodynamic regulation mechanisms can be assessed. In this paper we introduce an algorithm for the decomposition of NIRS signals into additive components...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27875190/combined-visualization-of-vessel-deformation-and-hemodynamics-in-cerebral-aneurysms
#16
Monique Meuschke, Samuel Voss, Oliver Beuing, Bernhard Preim, Kai Lawonn
We present the first visualization tool that combines patient-specific hemodynamics with information about the vessel wall deformation and wall thickness in cerebral aneurysms. Such aneurysms bear the risk of rupture, whereas their treatment also carries considerable risks for the patient. For the patient-specific rupture risk evaluation and treatment analysis, both morphological and hemodynamic data have to be investigated. Medical researchers emphasize the importance of analyzing correlations between wall properties such as the wall deformation and thickness, and hemodynamic attributes like the Wall Shear Stress and near-wall flow...
January 2017: IEEE Transactions on Visualization and Computer Graphics
https://www.readbyqxmd.com/read/27871568/discrepancy-between-electroencephalography-and-hemodynamics-in-a-patient-with-cockayne-syndrome-during-general-anesthesia
#17
Masanori Tsukamoto, Takashi Hitosugi, Takeshi Yokoyama
Cockayne syndrome is a kind of progeria with autosomal chromosome recessiveness described first by Cockayne in 1936. Patients with this syndrome were characterized by retarded growth, cerebral atrophy, and mental retardation. We experienced an anesthetic management of a patient with Cockayne syndrome, who underwent dental treatment twice. The primary concern was discrepancy between electroencephalography and hemodynamics. The values of bispectral index showed a sharp fall to 1 digit and suppression ratio more than 40, while hemodynamics was stable during induction of anesthesia with sevoflurane 8%...
December 2016: Journal of Clinical Anesthesia
https://www.readbyqxmd.com/read/27867719/monitoring-cerebral-oxygenation-and-local-field-potential-with-a-variation-of-isoflurane-concentration-in-a-rat-model
#18
Dong-Hyuk Choi, Teo Jeon Shin, Seonghyun Kim, Jayyoung Bae, Dongrae Cho, Jinsil Ham, Ji-Young Park, Hyoung-Ihl Kim, Seongwook Jeong, Boreom Lee, Jae Gwan Kim
We aimed to investigate experimentally how anesthetic levels affect cerebral metabolism measured by near-infrared spectroscopy (NIRS) and to identify a robust marker among NIRS parameters to discriminate various stages of anesthetic depth in rats under isoflurane anesthesia. In order to record the hemodynamic changes and local field potential (LFP) in the brain, fiber-optic cannulae and custom-made microelectrodes were implanted in the frontal cortex of the skull. The NIRS and LFP signals were continuously monitored before, during and after isoflurane anesthesia...
October 1, 2016: Biomedical Optics Express
https://www.readbyqxmd.com/read/27866455/changes-in-pulsatility-and-resistance-indices-of-cerebral-arteriovenous-malformation-feeder-arteries-after-embolization-and-surgery
#19
Sophia F Shakur, Sepideh Amin-Hanjani, Mohamed Abouelleil, Victor A Aletich, Fady T Charbel, Ali Alaraj
OBJECTIVES: Embolization reduces flow in cerebral arteriovenous malformations (AVMs) before surgical resection, but changes in pulsatility and resistance indices (PI, RI) are unknown. Here, we measure PI, RI in AVM arterial feeders before and after embolization/surgery. METHODS: Records of patients who underwent AVM embolization and surgical resection at our institution between 2007 and 2014 and had PI, RI, and flows obtained using quantitative magnetic resonance angiography were retrospectively reviewed...
November 21, 2016: Neurological Research
https://www.readbyqxmd.com/read/27861368/comparison-of-extracranial-artery-stenosis-and-cerebral-blood-flow-assessed-by-quantitative-magnetic-resonance-using-digital-subtraction-angiography-as-the-reference-standard
#20
Jingjing Cai, Dan Wu, Yongqian Mo, Anxin Wang, Shiyu Hu, Lijie Ren
Extracranial arteriosclerosis usually indicates a high risk of ischemic stroke. In the past, a clinical decision following diagnosis was dependent on the percentage of vessel stenosis determined by an invasive technique. We aimed to develop a quantitative magnetic resonance (QMR) technique to evaluate artery structure and cerebral hemodynamics noninvasively.QMR and digital subtraction angiography (DSA) were performed in 67 patients with suspected cerebral vascular disease at our hospital. Accuracy, sensitivity, positive predictive values (PPVs), negative predictive values (NPVs), and Pearson correlation coefficient of QMR were calculated and compared for the detection and measurement of vascular stenoses using DSA as a gold standard...
November 2016: Medicine (Baltimore)
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