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https://www.readbyqxmd.com/read/29238322/acute-ischemic-pediatric-stroke-management-an-extended-window-for-mechanical-thrombectomy
#1
Ashish Kulhari, Elizabeth Dorn, Jonathan Pace, Vilakshan Alambyan, Stephanie Chen, Osmond C Wu, Macym Rizvi, Anthony Hammond, Ciro Ramos-Estebanez
Ischemic stroke is a rare condition to afflict the pediatric population. Congenital cardiomyopathy represents one of several possible etiologies in children. We report a 9-year-old boy who developed right middle cerebral artery stroke secondary to primary restrictive cardiomyopathy. In the absence of pediatric guidelines, the child met adult criteria for mechanical thrombectomy given the small core infarct and large penumbra. The literature suggests children may benefit from mechanical thrombectomy in carefully selected cases...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/29236051/synchrotron-based-pencil-beam-scanning-nozzle-with-an-integrated-mini-ridge-filter-a-dosimetric-study-to-optimize-treatment-delivery
#2
Xianliang Wang, Yupeng Li, Xiaodong Zhang, Heng Li, Koichi Miyazaki, Rintaro Fujimoto, Hiroshi Akiyama, Michael T Gillin, Falk Poenisch, Narayan Sahoo, David Grosshans, Brandon Gunn, Steven Jay Frank, Pei Wang, Jinyi Lang, Qing Hou, Xiaorong Ronald Zhu
A mini-ridge filter is often used to widen the Bragg peak in the longitudinal direction at low energies but not high energies. To facilitate the clinical use of a mini-ridge filter, we performed a planning study for the feasibility of a mini-ridge filter as an integral part of the synchrotron nozzle (IMRF). Dose models with and without IMRF were commissioned in a commercial Treatment planning system (TPS). Dosimetric characteristics in a homogenous water phantom were compared between plans with and without IMRF for a fixed spread-out Bragg peak width of 4 cm with distal ranges varying from 8 to 30 g/cm²...
December 13, 2017: Cancers
https://www.readbyqxmd.com/read/29231236/relevance-of-the-cerebral-collateral-circulation-in-ischaemic-stroke-time-is-brain-but-collaterals-set-the-pace
#3
Simon Jung, Roland Wiest, Jan Gralla, Richard McKinley, Heinrich Mattle, David Liebeskind
Blood supply to the brain is secured by an extensive collateral circulation system, which can be divided into primary routes, i.e., the Circle of Willis, and secondary routes, e.g., collaterals from the external to the internal carotid artery and leptomeningeal collaterals. Collateral flow is the basis for acute stroke treatment, since neurones will only survive long enough to be rescued with reperfusion therapies if there is sufficient collateral flow. Poor collateral flow is associated with worse outcome and faster growth of larger infarcts in acute stroke treatment...
December 12, 2017: Swiss Medical Weekly
https://www.readbyqxmd.com/read/29222823/dominant-role-of-microglial-and-macrophage-innate-immune-responses-in-human-ischemic-infarcts
#4
Tobias Zrzavy, Joana Machado-Santos, Sheren Christine, Christoph Baumgartner, Howard L Weiner, Oleg Butovsky, Hans Lassmann
Inflammatory mechanisms, involving granulocytes, T-cells, B-cells, macrophages and activated microglia, have been suggested to play a pathogenic role in experimental models of stroke and may be targets for therapeutic intervention. However, knowledge on the inflammatory response in human stroke lesions is limited. Here, we performed a quantitative study on the inflammatory reaction in human ischemic infarct lesions. We found increased numbers of T-lymphocytes, mainly CD8+ cells, but not of B-lymphocytes. Their number was very low in comparison to that seen in inflammatory diseases of the central nervous system and they did not show signs of activation...
December 8, 2017: Brain Pathology
https://www.readbyqxmd.com/read/29218615/advanced-ct-for-diagnosis-of-seizure-related-stroke-mimics
#5
Friederike Austein, Monika Huhndorf, Johannes Meyne, Helmut Laufs, Olav Jansen, Thomas Lindner
BACKGROUND AND PURPOSE: It is assumed that up to 30 % of clinically diagnosed acute ischaemic strokes (AIS) are actually stroke mimics (SM). Our aim was to evaluate the usefulness of advanced CT including CT angiography (CTA) and CT perfusion (CTP) findings when distinguishing AIS from seizure-related SM. METHODS: Over a 22-month period data were gathered of patients who presented to our stroke centre with AIS-like symptoms and were examined immediately with an advanced CT, analysed and evaluated by two experienced neuroradiologists who preferred SM rather than AIS...
December 7, 2017: European Radiology
https://www.readbyqxmd.com/read/29216501/smart-coils-for-intracranial-aneurysm-embolization-initial-outcomes
#6
Adeel Ilyas, Thomas J Buell, Ching-Jen Chen, Dale Ding, Daniel M S Raper, Davis G Taylor, Jennifer D Sokolowski, Kenneth C Liu
OBJECTIVES: Endovascular technology for the treatment of intracranial aneurysms continues to rapidly evolve. The SMART coil (Penumbra Inc., Alameda, CA, USA) is a novel microcoil designed to enhance deliverability. The aim of this single-center, retrospective cohort study is to assess the initial outcomes after aneurysm embolization using SMART coils. PATIENTS AND METHODS: We reviewed consecutive patients with intracranial aneurysms who underwent endovascular embolization using SMART coils from June 2016 to January 2017...
December 2, 2017: Clinical Neurology and Neurosurgery
https://www.readbyqxmd.com/read/29205357/hexokinase-2-dependent-hyperglycolysis-driving-microglial-activation-contributes-to-ischemic-brain-injury
#7
Yuan Li, Bingzheng Lu, Longxiang Sheng, Zhu Zhu, Hongjiaqi Sun, Yuwei Zhou, Yang Yang, Dongdong Xue, Wenli Chen, Xuyan Tian, Yun Du, Min Yan, Wenbo Zhu, Fan Xing, Kai Li, Suizhen Lin, Pengxin Qiu, Xingwen Su, Yijun Huang, Guangmei Yan, Wei Yin
Hyperglycolysis, observed within the penumbra zone during brain ischemia, was shown to be detrimental for tissue survival due to lactate accumulation and reactive oxygen species (ROS) overproduction in clinical and experimental settings. Recently, mounting evidence suggests that glycolytic reprogramming and induced metabolic enzymes can fuel the activation of peripheral immune cells. However, the possible roles and details regarding hyperglycolysis in neuroinflammation during ischemia are relatively poorly understood...
December 5, 2017: Journal of Neurochemistry
https://www.readbyqxmd.com/read/29188434/photothrombotic-stroke-as-a-model-of-ischemic-stroke
#8
REVIEW
Anatoly B Uzdensky
The search of effective anti-stroke neuroprotectors requires various stroke models adequate for different aspects of the ischemic processes. The photothrombotic stroke model is particularly suitable for the study of cellular and molecular mechanisms underlying neurodegeneration, neuroprotection, and neuroregeneration. It is a model of occlusion of small cerebral vessels, which provides detailed study of molecular mechanisms of ischemic cell death and useful for search of potential anti-stroke agents. Its advantages include well-defined location and size of ischemic lesion that are determined by the aiming of the laser beam at the predetermined brain region; easy impact dosing by changing light intensity and duration; low invasiveness and minimal surgical intervention without craniotomy and mechanical manipulations with blood vessel, which carry the risk of brain trauma; low animal mortality and prolonged sensorimotor impairment that provide long-term study of stroke consequences including behavior impairment and recovery; independence on genetic variations of blood pressure and vascular architecture; and high reproducibility...
November 29, 2017: Translational Stroke Research
https://www.readbyqxmd.com/read/29183174/limit-of-intraoperative-near-infrared-spectroscopy-monitoring-during-endovascular-thrombectomy-in-acute-ischemic-stroke
#9
Ryo Hiramatsu, Motomasa Furuse, Ryokichi Yagi, Hiroyuki Ohnishi, Naokado Ikeda, Naosuke Nonoguchi, Shinji Kawabata, Shigeru Miyachi, Toshihiko Kuroiwa
Endovascular thrombectomy is recommended for a persistent ischemic penumbra if recanalization cannot be achieved by the intravenous (IV) administration of recombinant tissue-plasminogen activator (rt-PA) alone. Although endovascular thrombectomy is a powerful treatment for major cerebral artery occlusion, the monitoring of recanalization and reperfusion during acute ischemic stroke presents a therapeutic challenge, and a previous study reported the usefulness of near-infrared spectroscopy (NIRS) for intraoperative monitoring during emergency endovascular thrombectomy for acute large ischemic stroke...
January 1, 2017: Interventional Neuroradiology
https://www.readbyqxmd.com/read/29178546/evaluation-of-dosimetric-advantages-of-using-patient-specific-aperture-system-with-intensity-modulated-proton-therapy-for-the-shallow-depth-tumor
#10
Keisuke Yasui, Toshiyuki Toshito, Chihiro Omachi, Kensuke Hayashi, Kenichiro Tanaka, Kumiko Asai, Akira Shimomura, Rie Muramatsu, Naoki Hayashi
In this study, we evaluate dosimetric advantages of using patient-specific aperture system with intensity-modulated proton therapy (IMPT) for head and neck tumors at the shallow depth. We used four types of patient-specific aperture system (PSAS) to irradiate shallow regions less than 4 g/cm2 with a sharp lateral penumbra. Ten head and neck IMPT plans with or without aperture were optimized separately with the same 95% prescription dose and same dose constraint for organs at risk (OARs). The plans were compared using dose volume histograms (DVHs), dose distributions, and some dose indexes such as volume receiving 50% of the prescribed dose (V50 ), mean or maximum dose (Dmean and Dmax ) to the OARs...
November 27, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29178429/technical-note-defining-cyclotron-based-clinical-scanning-proton-machines-in-a-fluka-monte-carlo-system
#11
Francesca Fiorini, Niek Schreuder, Frank Van den Heuvel
PURPOSE: Cyclotron-based pencil beam scanning (PBS) proton machines represent nowadays the majority and most affordable choice for proton therapy facilities, however their representation in Monte Carlo (MC) codes is more complex than passively scattered proton system or synchrotron based PBS machines. This is because degraders are used to decrease the energy from the cyclotron maximum energy to the desired energy, resulting in a unique spot size, divergence and energy spread depending on the amount of degradation...
November 27, 2017: Medical Physics
https://www.readbyqxmd.com/read/29176074/validation-and-uncertainty-analysis-of-a-pre-treatment-2d-dose-prediction-model
#12
Jose A Baeza, Cecile J A Wolfs, Sebastiaan M J J G Nijsten, Frank Verhaegen
Independent verification of complex treatment delivery with megavolt photon beam radiotherapy (RT) has been effectively used to detect and prevent errors. This work presents the validation and uncertainty analysis of a model that predicts 2D portal dose images without a patient or phantom in the beam. The prediction model is based on an exponential point dose model with separable primary and secondary photon fluence components. The model includes a scatter kernel, off-axis ratio map, transmission values and penumbra kernels for beam-delimiting components...
November 26, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29173756/proton-therapy-for-head-and-neck-cancers
#13
REVIEW
Pierre Blanchard, Gary Brandon Gunn, Alexander Lin, Robert L Foote, Nancy Y Lee, Steven J Frank
Because of its sharp lateral penumbra and steep distal fall-off, proton therapy offers dosimetric advantages over photon therapy. In head and neck cancer, proton therapy has been used for decades in the treatment of skull-base tumors. In recent years the use of proton therapy has been extended to numerous other disease sites, including nasopharynx, oropharynx, nasal cavity and paranasal sinuses, periorbital tumors, skin, and salivary gland, or to reirradiation. The aim of this review is to present the physical properties and dosimetric benefit of proton therapy over advanced photon therapy; to summarize the clinical benefit described for each disease site; and to discuss issues of patient selection and cost-effectiveness...
January 2018: Seminars in Radiation Oncology
https://www.readbyqxmd.com/read/29172990/thresholds-for-infarction-vary-between-gray-matter-and-white-matter-in-acute-ischemic-stroke-a-ct-perfusion-study
#14
Chushuang Chen, Andrew Bivard, Longting Lin, Christopher R Levi, Neil J Spratt, Mark W Parsons
We aimed to investigate optimal perfusion thresholds defining ischemic core and penumbra for hemispheric-cortical gray matter (GM) and subcortical white matter (WM). A total of 65 sub-6 h ischemic stroke patients were assessed, who underwent acute computed tomography perfusion (CTP) and acute magnetic resonance imaging. CTP maps were generated by both standard singular value deconvolution (sSVD) and SVD with delay and dispersion correction (ddSVD). Analyses were undertaken to calculate sensitivity, specificity, and area under the curve (AUC) for each CTP threshold for core and penumbra in GM and WM...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/29163033/phosphorylation-at-s153-as-a-functional-switch-of-phosphatidylethanolamine-binding-protein-1-in-cerebral-ischemia-reperfusion-injury-in-rats
#15
Zhong Wang, Jiyuan Bu, Xiyang Yao, Chenglin Liu, Haitao Shen, Xiang Li, Haiying Li, Gang Chen
This study aimed to estimate the role of phosphatidylethanolamine binding protein 1 (PEBP1) in cerebral ischemia-reperfusion (I/R) injury and the underlying mechanisms. Middle cerebral artery occlusion/reperfusion (MCAO/R) model in adult male Sprague Dawley rats (250-280 g) were established and cultured neurons were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) to mimic I/R injury in vitro. Expression vectors encoding wild-type PEBP1 and PEBP1 with Ser153Ala mutation (S153A), PEBP1 specific siRNAs, and human recombinant PEBP1 (rhPEBP1) were administered intracerebroventricularly...
2017: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/29156098/technical-note-penumbral-width-trimming-in-solid-lung-dose-profiles-for-0-9-and-1-5-t-mri-linac-prototypes
#16
Sarah J Alnaghy, Jarrad Begg, Trent Causer, Thahabah Alharthi, Laura Glaubes, Bin Dong, Armia George, Lois Holloway, Peter Metcalfe
PURPOSE: Longitudinal magnetic fields narrow beam penumbra and tighten lateral spread of secondary electrons in air cavities, including lung tissue. Gafchromic® EBT3 film was used to investigate differences between penumbra in solid water and solid lung, without a magnetic field (0 T) and with two field strengths (0.9 and 1.5 T). METHODS: The first prototype of the Australian MRI-linac consisted of a 1.5 T Siemens Sonata MRI and Varian industrial linatron (nominal 4 MV)...
November 20, 2017: Medical Physics
https://www.readbyqxmd.com/read/29148900/combined-interventional-and-surgical-treatment-of-tandem-middle-cerebral-artery-embolus-and-internal-carotid-artery-occlusion-case-report
#17
Mark B Frenkel, Jaclyn J Renfrow, Jasmeet Singh, Nitin Garg, Stacey Q Wolfe
Tandem internal carotid artery (ICA) origin occlusion and middle cerebral artery (MCA) thromboembolism is a life-threatening condition with poor neurological outcome. The authors report on a patient presenting with acute ischemic stroke from a tandem ICA and MCA occlusion with penumbra. Emergency MCA mechanical thrombectomy was performed through percutaneous cervical ICA access due to the inability to cross the cervical carotid occlusion. Emergency carotid endarterectomy to reperfuse the poorly collateralized hemisphere and repair the ICA access site was performed 2 hours after completion of tissue plasminogen activator (tPA) infusion...
November 17, 2017: Journal of Neurosurgery
https://www.readbyqxmd.com/read/29148575/effects-of-spot-parameters-in-pencil-beam-scanning-treatment-planning
#18
Aafke Christine Kraan, Nicolas Depauw, Ben Clasie, Marina Giunta, Tom Madden, Hanne M Kooy
BACKGROUND: Spot size σ (in-air at isocenter), inter-spot spacing d, and spot charge q influence dose delivery efficiency and plan quality in Intensity Modulated Proton Therapy (IMPT) treatment planning. The choice and range of parameters varies among different manufacturers. The goal of this work is to demonstrate the influence of the spot parameters on dose quality and delivery in IMPT treatment plans, to show their interdependence, and to make practitioners aware of the spot parameter values for a certain facility...
November 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/29140184/refining-the-ischemic-penumbra-with-topography
#19
Tharani Thirugnanachandran, Henry Ma, Shaloo Singhal, Lee-Anne Slater, Stephen M Davis, Geoffrey A Donnan, Thanh Phan
It has been 40 years since the ischemic penumbra was first conceptualized through work on animal models. The topography of penumbra has been portrayed as an infarcted core surrounded by penumbral tissue and an extreme rim of oligemic tissue. This picture has been used in many review articles and textbooks before the advent of modern imaging. In this paper, we review our understanding of the topography of the ischemic penumbra from the initial experimental animal models to current developments with neuroimaging which have helped to further define the temporal and spatial evolution of the penumbra and refine our knowledge...
January 1, 2017: International Journal of Stroke: Official Journal of the International Stroke Society
https://www.readbyqxmd.com/read/29136153/reverse-ncx-attenuates-cellular-sodium-loading-in-metabolically-compromised-cortex
#20
Niklas J Gerkau, Cordula Rakers, Simone Durry, Gabor C Petzold, Christine R Rose
In core regions of ischemic stroke, disruption of blood flow causes breakdown of ionic gradients and, ultimately, calcium overload and cell death. In the surrounding penumbra, cells may recover upon reperfusion, but recovery is hampered by additional metabolic demands imposed by peri-infarct depolarizations (PIDs). There is evidence that sodium influx drives PIDs, but no data exist on PID-related sodium accumulations in vivo. Here, we found that PIDs in mouse neocortex are associated with propagating sodium elevations in neurons and astrocytes...
November 9, 2017: Cerebral Cortex
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