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https://www.readbyqxmd.com/read/28214420/prevention-of-radiotherapy-induced-neurocognitive-dysfunction-in-survivors-of-paediatric-brain-tumours-the-potential-role-of-modern-imaging-and-radiotherapy-techniques
#1
REVIEW
Thankamma Ajithkumar, Stephen Price, Gail Horan, Amos Burke, Sarah Jefferies
Neurocognitive dysfunction is the leading cause of reduced quality of life in long-term survivors of paediatric brain tumours. Radiotherapy is one of the main contributors to neurocognitive sequelae. Current approaches for prevention and reduction of neurocognitive dysfunction include avoidance of radiotherapy in young children and reduction of the radiotherapy dose and volume of brain irradiated. Substantial advances have been made in brain imaging, especially with functional imaging and fibre tracking with the use of diffusion tensor imaging...
February 2017: Lancet Oncology
https://www.readbyqxmd.com/read/28214332/comparison-of-several-white-matter-tracts-in-feline-and-canine-brain-by-using-magnetic-resonance-diffusion-tensor-imaging
#2
Olivier Jacqmot, Bert Van Thielen, Alex Michotte, Inneke Willekens, Filip Verhelle, Peter Goossens, Filip De Ridder, Jan Pieter Clarys, Anne Vanbinst, Cindy Peleman, Johan de Mey
Recently, we published a first anatomical Diffusion Tensor Imaging (DTI) atlas regarding white matter tracts in the canine brain. The purpose of this study was to show the significance of DTI in the revelation of the white matter fibres in the feline brain (i.e. to obtain an anatomical DTI atlas of images) and to descriptively compare these to previously obtained white matter fibre images of the canine brain. DTI MR Images of 4 cats euthanised for reasons other than neurological disorders were obtained with a 3 T system...
February 18, 2017: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
https://www.readbyqxmd.com/read/28213111/childhood-maltreatment-is-associated-with-alteration-in-global-network-fiber-tract-architecture-independent-of-history-of-depression-and-anxiety
#3
Kyoko Ohashi, Carl M Anderson, Elizabeth A Bolger, Alaptagin Khan, Cynthia E McGreenery, Martin H Teicher
Childhood maltreatment is a major risk factor for psychopathology. It is also associated with alterations in the network architecture of the brain, which we hypothesized may play a significant role in the development of psychopathology. In this study, we analyzed the global network architecture of physically healthy unmedicated 18-25 year old subjects (n=262) using diffusion tensor imaging (DTI) MRI and tractography. Anatomical networks were constructed from fiber streams interconnecting 90 cortical or subcortical regions for subjects with no-to-low (n=122) versus moderate-to-high (n=140) exposure to maltreatment...
February 14, 2017: NeuroImage
https://www.readbyqxmd.com/read/28211459/gravitational-body-forces-focus-north-american-intraplate-earthquakes
#4
Will Levandowski, Mark Zellman, Rich Briggs
Earthquakes far from tectonic plate boundaries generally exploit ancient faults, but not all intraplate faults are equally active. The North American Great Plains exemplify such intraplate earthquake localization, with both natural and induced seismicity generally clustered in discrete zones. Here we use seismic velocity, gravity and topography to generate a 3D lithospheric density model of the region; subsequent finite-element modelling shows that seismicity focuses in regions of high-gravity-derived deviatoric stress...
February 17, 2017: Nature Communications
https://www.readbyqxmd.com/read/28210733/super-high-energy-density-single-bonded-trigonal-nitrogen-allotrope-a-chemical-twin-of-the-cubic-gauche-form-of-nitrogen
#5
Sergey V Bondarchuk, Boris F Minaev
A new ambient-pressure metastable single-bonded 3D nitrogen allotrope (TrigN) of trigonal symmetry (space group R3[combining macron]) was calculated using density functional theory (DFT). A comprehensive characterization of this material, comprising thermodynamic, elastic, and spectral (vibrational, UV-vis absorption, and nuclear magnetic resonance) properties, was performed. Using high-throughput band structure calculation, the TrigN phase was characterized as an insulator with an indirect band gap of 2.977 eV...
February 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28210731/pressure-driven-phase-transition-mechanisms-revealed-by-quantum-chemistry-l-serine-polymorphs
#6
Denis A Rychkov, Jernej Stare, Elena V Boldyreva
The present study delivers a computational approach for the understanding of the mechanism of phase transitions between polymorphs of small organic molecules. By using state of the art periodic DFT calculations augmented with dispersion corrections and an external stress tensor together with gas-phase cluster calculations, we thoroughly explained the reversible phase transitions of three polymorphs of the model system, namely crystalline l-serine in the pressure range up to 8 GPa. This study has shown that at the macroscopic level the main driving force of the phase transitions is the decrease in the volume of the crystal unit cell, which contributes to the enthalpy difference between the two forms, but not to the difference in their internal crystal energies...
February 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28210542/dynamic-association-between-perfusion-and-white-matter-integrity-across-time-since-injury-in-veterans-with-history-of-tbi
#7
Alexandra L Clark, Katherine J Bangen, Scott F Sorg, Dawn M Schiehser, Nicole D Evangelista, Benjamin McKenna, Thomas T Liu, Lisa Delano-Wood
OBJECTIVE: Cerebral blood flow (CBF) plays a critical role in the maintenance of neuronal integrity, and CBF alterations have been linked to deleterious white matter changes. Although both CBF and white matter microstructural alterations have been observed within the context of traumatic brain injury (TBI), the degree to which these pathological changes relate to one another and whether this association is altered by time since injury have not been examined. The current study therefore sought to clarify associations between resting CBF and white matter microstructure post-TBI...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28210274/bilateral-tensor-fasciae-suralis-muscles-in-a-cadaver-with-unilateral-accessory-flexor-digitorum-longus-muscle
#8
Logan S W Bale, Sean O Herrin
Muscle variants are routinely encountered in the dissection laboratory and in clinical practice and therefore anatomists and clinicians need to be aware of their existence. Here we describe two different accessory muscles identified while performing educational dissection of a 51-year-old male cadaver. Tensor fasciae suralis, a rare muscle variant, was identified bilaterally and accessory flexor digitorum longus, a more common muscle variant, was present unilaterally. Tensor fasciae suralis and accessory flexor digitorum longus are clinically relevant muscle variants...
2017: Case Reports in Medicine
https://www.readbyqxmd.com/read/28209583/combining-diffusion-tensor-metrics-and-dsc-perfusion-imaging-can-it-improve-the-diagnostic-accuracy-in-differentiating-tumefactive-demyelination-from-high-grade-glioma
#9
S B Hiremath, A Muraleedharan, S Kumar, C Nagesh, C Kesavadas, M Abraham, T R Kapilamoorthy, B Thomas
BACKGROUND AND PURPOSE: Tumefactive demyelinating lesions with atypical features can mimic high-grade gliomas on conventional imaging sequences. The aim of this study was to assess the role of conventional imaging, DTI metrics (p:q tensor decomposition), and DSC perfusion in differentiating tumefactive demyelinating lesions and high-grade gliomas. MATERIALS AND METHODS: Fourteen patients with tumefactive demyelinating lesions and 21 patients with high-grade gliomas underwent brain MR imaging with conventional, DTI, and DSC perfusion imaging...
February 16, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28209580/white-matter-tract-pathology-in-pediatric-anoxic-brain-injury-from-drowning
#10
M Ishaque, J H Manning, M D Woolsey, C G Franklin, F S Salinas, P T Fox
BACKGROUND AND PURPOSE: Although drowning is a leading cause of mortality and morbidity in young children, the neuropathologic consequences have not been fully determined. The purpose of this article was to quantitatively characterize white matter microstructural abnormalities in pediatric anoxic brain injury from nonfatal drowning and investigate the correlation with motor function. MATERIALS AND METHODS: Whole-brain T1-weighted and diffusion-weighted MR imaging datasets were acquired in 11 children with chronic anoxic brain injury and 11 age- and sex-matched neurotypical controls (4-12 years of age)...
February 16, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28209179/the-social-brain-network-in-22q11-2-deletion-syndrome-a-diffusion-tensor-imaging-study
#11
Amy K Olszewski, Zora Kikinis, Christie S Gonzalez, Ioana L Coman, Nikolaos Makris, Xue Gong, Yogesh Rathi, Anni Zhu, Kevin M Antshel, Wanda Fremont, Marek R Kubicki, Sylvain Bouix, Martha E Shenton, Wendy R Kates
BACKGROUND: Chromosome 22q11.2 deletion syndrome (22q11.2DS) is a neurogenetic disorder that is associated with a 25-fold increase in schizophrenia. Both individuals with 22q11.2DS and those with schizophrenia present with social cognitive deficits, which are putatively subserved by a network of brain regions that are involved in the processing of social cognitive information. This study used two-tensor tractography to examine the white matter tracts believed to underlie the social brain network in a group of 57 young adults with 22q11...
February 16, 2017: Behavioral and Brain Functions: BBF
https://www.readbyqxmd.com/read/28208451/mori-zwanzig-theory-for-dissipative-forces-in-coarse-grained-dynamics-in-the-markov-limit
#12
Sergei Izvekov
We derive alternative Markov approximations for the projected (stochastic) force and memory function in the coarse-grained (CG) generalized Langevin equation, which describes the time evolution of the center-of-mass coordinates of clusters of particles in the microscopic ensemble. This is done with the aid of the Mori-Zwanzig projection operator method based on the recently introduced projection operator [S. Izvekov, J. Chem. Phys. 138, 134106 (2013)10.1063/1.4795091]. The derivation exploits the "generalized additive fluctuating force" representation to which the projected force reduces in the adopted projection operator formalism...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28208424/geometric-approach-to-optimal-nonequilibrium-control-minimizing-dissipation-in-nanomagnetic-spin-systems
#13
Grant M Rotskoff, Gavin E Crooks, Eric Vanden-Eijnden
Optimal control of nanomagnets has become an urgent problem for the field of spintronics as technological tools approach thermodynamically determined limits of efficiency. In complex, fluctuating systems, such as nanomagnetic bits, finding optimal protocols is challenging, requiring detailed information about the dynamical fluctuations of the controlled system. We provide a physically transparent derivation of a metric tensor for which the length of a protocol is proportional to its dissipation. This perspective simplifies nonequilibrium optimization problems by recasting them in a geometric language...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28208413/friction-factor-for-aerosol-fractal-aggregates-over-the-entire-knudsen-range
#14
James Corson, George W Mulholland, Michael R Zachariah
We develop an approach for computing the hydrodynamic friction tensor and scalar friction coefficient for an aerosol fractal aggregate in the transition regime. Our approach involves solving the Bhatnagar-Gross-Krook equation for the velocity field around a sphere and using the velocity field to calculate the force on each primary sphere in the aggregate due to the presence of the other spheres. It is essentially an extension of Kirkwood-Riseman theory from the continuum flow regime to the entire Knudsen range (Knudsen number from 0...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28207659/evaluation-of-dti-parameter-ratios-and-diffusion-tensor-tractography-grading-in-the-diagnosis-and-prognosis-prediction-of-cervical-spondylotic-myelopathy
#15
Kun Wang, Zhi Chen, Fan Zhang, Qingxin Song, Canglong Hou, Yixing Tang, Jun Wang, Shiyue Chen, Yun Bian, Qiang Hao, Hongxing Shen
STUDY DESIGN: Prospective cohort. OBJECTIVE: To explore the correlations between diffusion tensor imaging (DTI) ratios and diffusion tensor tractography (DTT) grading with clinical symptoms and outcomes of cervical spondylotic myelopathy (CSM). SUMMARY OF BACKGROUND DATA: In addition to magnetic resonance imaging (MRI) and computed tomography, DTI may be useful in understanding pathophysiology of spinal cord in earlier stages of the CSM but it may be confounded by age and cervical level, and previous studies had small sample sizes...
February 15, 2017: Spine
https://www.readbyqxmd.com/read/28207526/restoration-of-the-ascending-reticular-activating-system-compressed-by-hematoma-in-a-stroke-patient
#16
Sung Ho Jang, Jeong Pyo Seo
RATIONALE: We report on restoration of the ascending reticular activating system (ARAS), compressed by an intracerebral hematoma and perihematomal edema following a stroke. The restoration of the ARAS was demonstrated by diffusion tensor tractography (DTT). PATIENT CONCERNS: In a 60-year-old male, a brain MRI taken at 2 weeks after the surgery showed a hematoma and perihematomal edema in the left posterolateral pons and cerebellum, which were markedly resolved on a brain MRI after 5 weeks...
February 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28205341/spatiotemporal-microstructural-white-matter-changes-in-diffusion-tensor-imaging-after-transient-focal-ischemic-stroke-in-rats
#17
Won-Beom Jung, Yong Hee Han, Julius Juhyun Chung, Sun Young Chae, Sung Hoon Lee, Geun Ho Im, JiHoon Cha, Jung Hee Lee
Structural reorganization in white matter (WM) after stroke is a potential contributor to substitute or to newly establish the functional field on the injured brain in nature. Diffusion tensor imaging (DTI) is an imaging modality that can be used to evaluate damage and recovery within the brain. This method of imaging allows for in vivo assessment of the restricted movements of water molecules in WM and provides a detailed look at structural connectivity in the brain. For longitudinal DTI studies after a stroke, the conventional region of interest method and voxel-based analysis are highly dependent on the user-hypothesis and parameter settings for implementation...
February 16, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28203530/longitudinal-evaluation-of-cerebral-and-spinal-cord-damage-in-amyotrophic-lateral-sclerosis
#18
Milena de Albuquerque, Lucas Melo T Branco, Thiago Junqueira R Rezende, Helen Maia Tavares de Andrade, Anamarli Nucci, Marcondes Cavalcante França
OBJECTIVE: To evaluate MRI-based parameters as biomarkers of Amyotrophic Lateral Sclerosis (ALS) progression. METHODS: Twenty-seven patients and 27 controls performed two clinical and MRI acquisitions 8 months apart. ALSFRS-R scale was used to quantify disease severity at both time points. Multimodal analyses of MRI included cortical thickness measurements (FreeSurfer software), analysis of white matter integrity using diffusion-tensor imaging (tract-based spatial statistics-TBSS) and measurement of cervical spinal cord cross-sectional area (SpineSeg software)...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28203039/quality-assurance-using-outlier-detection-on-an-automatic-segmentation-method-for-the-cerebellar-peduncles
#19
Ke Li, Chuyang Ye, Zhen Yang, Aaron Carass, Sarah H Ying, Jerry L Prince
Cerebellar peduncles (CPs) are white matter tracts connecting the cerebellum to other brain regions. Automatic segmentation methods of the CPs have been proposed for studying their structure and function. Usually the performance of these methods is evaluated by comparing segmentation results with manual delineations (ground truth). However, when a segmentation method is run on new data (for which no ground truth exists) it is highly desirable to efficiently detect and assess algorithm failures so that these cases can be excluded from scientific analysis...
February 27, 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/28201911/semi-empirical-refinements-of-crystal-structures-using-17-o-quadrupolar-coupling-tensors
#20
Sean T Holmes, Robbie J Iuliucci, Karl T Mueller, Cecil Dybowski
We demonstrate a modification of Grimme's two-parameter empirical dispersion force field (referred to as the PW91-D2* method), in which the damping function has been optimized to yield geometries that result in predictions of the principal values of (17)O quadrupolar-coupling tensors that are systematically in close agreement with experiment. The predictions of (17)O quadrupolar-coupling tensors using PW91-D2*-refined structures yield a root-mean-square deviation (RMSD) (0.28 MHz) for twenty-two crystalline systems that is smaller than the RMSD for predictions based on X-ray diffraction structures (0...
February 14, 2017: Journal of Chemical Physics
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