1,720,993 research outputs found
Baseline preadjuvant magnetic resonance imaging for response assessment and for planning radiotherapy in glioblastoma.
No full textNo abstract availabl
In-vivo quantification of brain microstructure: a preliminary analysis using the SHORE diffusion model
No full textDiffusion MRI is capable of quantifying in-vivo water diffusivity in the brain tissues. Although widely used
in clinic, DTI1 suffers from the limitation of using a Gaussian to model white matter fibers, as in the case of fiber crossings.
Simple Harmonic Oscillator based Reconstruction and Estimation2 (SHORE) allows to calculate the Orientation Distribution
Function (ODF) and also to extract different scalar indices that can provide accurate estimation of microstructural properties
of the brain tissues, including Propagator Anisotropy (PA), Mean Square Displacement (MSD), Return To the Origin
Probability (RTOP), Return To the Axis Probability (RTAP) and Return To the Plane Probability (RTPP)
Reproducibility of BOLD signal change induced by breath holding.
No full textBlood oxygen level dependent (BOLD) contrast is influenced by some physiological factors such as blood flow and blood volume that can be a source of variability in fMRI analysis. Previous studies proposed to use the cerebrovascular response data to normalize or calibrate BOLD maps in order to reduce variability of fMRI data both among brain areas in single subject analysis and across subjects. Breath holding is one of the most widely used methods to investigate the vascular reactivity. However, little is known about the robustness and reproducibility of this procedure. In this study we investigated three different breath holding periods. Subjects were asked to hold their breath for 9, 15 or 21 s in three separate runs and the fMRI protocol was repeated after 15 to 20 days. Our data show that the BOLD response to breath holding after inspiration results in a complex shape due to physiological factors that influence the signal variation with a timing that is highly reproducible. Nevertheless, the reproducibility of the magnitude of the cerebrovascular response to CO2, expressed as amplitude of BOLD signal and number of responding voxels, strongly depends on duration of breath holding periods. Breath holding period of 9 s results in high variability of the magnitude of the response while longer breath holding durations produce more robust and reproducible BOLD responses
Anarchy in the brain: Behavioural and neuroanatomical core of the anarchic hand syndrome
No full textAn individual's inability to control the movements of their own hand is known as the Anarchic Hand Syndrome. The hand may perform apparently purposeful actions but acts as if it has a will of its own. Although the syndrome was first described over a century ago, the nature of the condition remains, for the most part, obscure, in particular in terms of the definition of the main symptoms and the underlying neural networks. The present study compares the results from in-depth assessments, made at repeated intervals (2, 4 and 7 months from the lesion onset) of the anarchic hand symptoms in three patients suffering from various different forms of brain damage. An investigation of direct grey matter damage and structural connectivity allowed us to compare the grey matter lesions and white matter disconnections in the three patients. A “core” characteristic relating to anarchic hand symptoms was identified, involving, in particular, both apparently purposeful movements (i.e., magnetic apraxia, grasping, bimanual incoordination, disorders in manual dexterity and action sequencing) and non-purposeful movements (i.e., levitation, synkinesis and mirror movements). Furthermore, ideomotor apraxia may also be associated with this syndrome. No overlapping areas of grey matter lesions were found in the three patients. In contrast, a pattern of common white matter disconnections was found, which involves inter-hemispheric disconnections (via corpus callosum), the long intra-hemispheric tracts (via SLF, IFOF and Arcuate) and the descendent tracts (corticospinal tract). These results are discussed in terms of awareness of motor intention
Gamma knife radiosurgery in cavernous sinus meningiomas: results on 170 patients with at least 10-year-follow up period
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Early progression between surgery and adjuvant chemo-radiotherapy in glioblastoma.
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Diffusion tensor imaging corticospinal tractography in gamma knife radiosurgery for arterio-venous malformations.
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Radiosurgical options in neuro-oncology: a review on current tenets and future opportunities. Part II: adjuvant radiobiological tools
No full textStereotactic radiosurgery (SRS) is currently a well-established, minimally invasive treatment for many primary and secondary tumors, especially deep-sited lesions for which traditional neurosurgical procedures were poorly satisfactory or not effective at all. The initial evolution of SRS was cautious, relying on more than 30 years of experimental and clinical work that preceded its introduction into the worldwide medical community. This path enabled a brilliant present, and the continuous pace of technological advancement holds promise for a brighter future. Part II of this review article will cover the impact of multimodal adjuvant technologies on SRS, and their input to the crucial role played by neurosurgeons, radiation oncologists and medical physicists in the management and care of fragile neuro-oncological patients
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