Download or read book Assessment of Brain Perfusion and Vascular Compliance with Magnetic Resonance Imaging written by Yang Li and published by . This book was released on 2018 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measuring Resting Cerebral Perfusion using Magnetic Resonance Imaging MRI written by James Duffin and published by Frontiers Media SA. This book was released on 2024-07-12 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: The acquisition of resting cerebral perfusion measures using magnetic resonance imaging (MRI) is one of the assessments of cerebrovascular health used to discern how well patients are coping with anatomical changes such as stenosis, and other factors impacting the supply of blood flow to the brain. Perfusion measures may be obtained using several MRI based techniques including arterial spin labeling (ASL) and dynamic contrast enhanced methods that rely on injected contrast agents such as gadolinium. Recently hypoxia-induced changes in deoxyhemoglobin have been used as a non-invasive contrast agent, measuring the resulting changes in blood oxygen dependent (BOLD) signals with MRI. With each approach, the means through which voxel-wise cerebral perfusion information is derived differs, leading to the development a variety of analysis methods in recent studies. This Research Topic is intended to attract manuscripts that advance the use of resting cerebral perfusion measures in clinical assessments of cerebrovascular health. In pursuit of this aim a better understanding of several aspects are needed.
Download or read book Clinical Perfusion MRI written by Peter B. Barker and published by Cambridge University Press. This book was released on 2013-05-16 with total page 373 pages. Available in PDF, EPUB and Kindle. Book excerpt: This concise and comprehensive review uniquely contains all the information required to perform and interpret clinical MR perfusion imaging.
Download or read book Advancing Functional Assessment with Flow sensitive Magnetic Resonance Imaging written by Grant Steven Roberts (Ph.D.) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phase-contrast magnetic resonance imaging (PC-MRI) is a non-invasive imaging method capable of quantifying time-resolved hemodynamics. This dissertation aims to develop novel acquisition methods and post-processing tools for the robust assessment of intracranial and aortic hemodynamics using PC-MRI and to study their relationship with aging and neurodegeneration. The associations between cerebrovascular health, arterial stiffness, aging, and neurodegeneration are poorly understood. 4D flow MRI is a noninvasive, quantitative imaging technique well-suited for the comprehensive assessment of cerebrovascular anatomy and function. However, its use in large-scale studies and clinical translation requires automation and robustness to accurately visualize and quantify hemodynamic parameters of interest. Currently, no adequate freely-available analysis tools exist and commercial post-processing packages are targeted toward cardiac applications. Here, I develop and validate a method to improve 4D flow MRI streamlines for generating 'virtual injections', enabling visualization of complex blood flow patterns in the brain. In addition, I introduce and validate an automated tool designed for simplified, robust, and reproducible cranial 4D flow MRI analysis, reducing post-processing times and interobserver variability. This tool is subsequently used to establish normative intracranial hemodynamics in one of the largest 4D flow studies to date from 759 older adults. Blood flow rates and pulsatility indices are tabulated in all major intracranial vessels and show a strong age dependency. This tool is also used to assess the relationship between cerebrovascular hemodynamics and white matter microstructure in cognitively unimpaired and Alzheimer's disease subjects. We find that white matter integrity is reduced in Alzheimer's disease and that white matter microstructure correlates with cerebral blood flow and pulsatility in cognitively unimpaired subjects. Furthermore, aortic stiffening, caused by aging or cardiovascular disease, can propagate harmful pulsatility into the cerebral microvasculature. PC-MRI methods have been developed to probe aortic stiffness by measuring pulse wave velocity (PWV), however, temporal resolution and breath-holds are methodological limitations, particularly in older adults. A free-breathing, radial, 2D-PC sequence with advanced image reconstruction is introduced to overcome these limitations and is validated in a custom-manufactured aortic phantom. Obtained PWVs are repeatable and comparable to standard breath-hold sequences. The image acquisition is further advanced by using a simultaneous multislice acquisition and reconstruction methodology to acquire two PC slices simultaneously which reduces scan time, improves physiological consistency, and maintains image quality. Together, these novel post-processing and acquisition techniques provide a means to quantitatively and comprehensively assess both intracranial and aortic vascular health. Using these techniques, a strong relationship between aging, aortic stiffness, cerebral blood flow and pulsatility, and white matter integrity was observed in older adults. These methods and results will help elucidate the pathophysiological contributions of vascular health in the context of aging and neurodegeneration.
Download or read book Introduction to Perfusion Quantification Using Arterial Spin Labelling written by Michael Chappell and published by Oxford University Press. This book was released on 2018 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: ASL is an increasingly popular tool to study the brain. The aim of this primer is to equip someone new to the field with the knowledge to make informed choices about ASL acquisition and analysis. While providing a stand-alone introduction to this subject, the text can be read with others in the series for a comprehensive overview of neuroimaging.
Download or read book Quantitative Assessment of Brain Perfusion with Magnetic Resonance Imaging written by Egbert Jan Willem Bleeker and published by . This book was released on 2011 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cerebrovascular Reactivity written by Jean Chen and published by Humana. This book was released on 2021-11-06 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides a comprehensive overview of the methodology, physiology, and contemporary and novel applications of cerebrovascular reactivity (CVR) measurements. The chapters in this book cover topics such as an introduction of the neurophysiology, neuroimaging, and clinical methods for CVR measurement; the use of CVR methods in the study of aging, cerebrovascular dysfunction, dementia, and brain tumors; and recommendations for measurement protocols and future applications in clinical translation. In Neuromethods series style, chapters include the kind of detail and key advice from the specialists needed to get successful results in your research center and clinical investigation. Thorough and comprehensive, Cerebrovascular Reactivity: Methodological Advances and Clinical Applications is a valuable tool that provides researchers in neuroscience and neurology with the latest resources on the measurement, interpretation, and application of CVR measurement.
Download or read book Acquisition and Processing Techniques for Rapid Robust and Patient specific Measurement of Cerebral Diffusion and Perfusion Using Magnetic Resonance Imaging written by Nora-Josefin Breutigam and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic resonance imaging (MRI) is a powerful technique that enables accurate medical diagnoses. Not only does it allow the visualization of static tissue contrasts, but it also provides the ability to measure the function and physiology behind important life processes. This dissertation presents two methods for imaging physiological effects, namely diffusion and perfusion. For diffusion-weighted imaging, but not limited to this application, a technique called simultaneous multi-contrast (SMC) imaging is introduced to acquire multiple image contrasts from different scan types within a single measurement. This technique offers new opportunities in clinical protocols where examination time is a critical factor and multiple image contrasts need to be acquired. The method was tested in a phantom and healthy subjects. The results showed that simultaneous acquisition of two contrasts (here diffusion-weighted imaging and T2*-weighting) with SMC imaging is possible with robust contrast separation and minimal impact on image quality. Thereby, the simultaneous acquisition of multiple contrasts reduces the overall examination time and there is inherent registration between contrasts. For cerebral perfusion-weighted imaging, the goal of this work was to increase the robustness of time-encoded arterial spin labeling (ASL) to image artifacts by adjusting the timing of imaging during active scanning individually for each subject. One of the major challenges in ASL imaging is the high variability of arterial transit times (ATT), which leads to arterial transit delay (ATD) artifacts. In particular, in patients with pathologic changes, these artifacts occur when post-labeling delay (PLD) and bolus duration are not optimally matched to the individual, resulting in difficult quantification of cerebral blood flow (CBF) and ATT. This is also true for the free-lunch (FL) approach in Hadamard-encoded pseudocontinuous ASL (H-pCASL). The method was tested in healthy subjects, with FL-bolus timing individualized by the developed and implemented adaptive H-pCASL sequence in combination with an automatic feedback algorithm. Automatic subject-specific adjustment of the FL-bolus PLD during an ongoing measurement may reduce uncertainties in perfusion quantification and reduce the number of cases in which measurements have to be repeated because the recommended timing does not fit the patient.
Download or read book Signal Processing Tools of MRI Perfusion weighted Imaging Data Analysis written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In dynamic susceptibility contrast (DSC) magnetic resonance (MR) approaches, by injecting a bolus of paramagnetic contrast agent intravenously, the measured MR signal is converted to a concentration time course to estimate hemodynamic parameters like cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT). Before estimating hemodynamic parameters, recirculation effects need to be removed by a gamma-variate fit of the concentration curve. In this dissertation, however, it has been found and demonstrated by simulation that fitting may not discern recirculation from the first-pass in case of cerebral ischemia. A new methodology using temporal independent component analysis (ICA) to remove recirculation in both normal and ischemic brain tissues while preserving the first-pass is therefore proposed. This should improve hemodynamics accuracy particularly in ischemic lesions. In DSC MR approaches, bolus delays between the arterial input function (AIF) and tissue curves may induce significant CBF quantification error. Our second contribution is using ICA to estimate bolus arrival time for each 5x5 region of interest (ROI) throughout the brain parenchyma. A global AIF measured from a major artery can then be shifted in accordance to define a local AIF for each ROI. The bolus delay may therefore be minimized, and the general shape of the AIF is preserved. This should improve the flow quantification. Transfer function has been widely used to characterize an unknown system. In DSC MR approaches, vascular transfer function (VTF) represents the probability density function of the vascular transit time. Our third contribution is to propose a new tool to estimate intracranial VTF non-invasively. This should provide an alternative means of assessing tissue perfusion status, particularly in patients with cerebrovascular diseases. Bolus dispersion between the AIF and tissue curves may induce flow quantification error, which cannot be minimized without the kno.
Download or read book Assessment of Collateral Blood Flow in the Brain Using Magnetic Resonance Imaging written by Thomas W. Okell and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Collateral blood flow is the compensatory flow of blood to the tissue through secondary channels when the primary channel is compromised. It is of vital importance in cerebrovascular disease where collateral flow can maintain large regions of brain tissue which would otherwise have suffered ischaemic damage. Traditional x-ray based techniques for visualising collateral flow are invasive and carry risks to the patient. In this thesis novel magnetic resonance imaging tech- niques for performing vessel-selective labelling of brain feeding arteries are ex- plored and developed to reveal the source and extent of collateral flow in the brain non-invasively and without the use of contrast agents. Vessel-encoded pseudo-continuous arterial spin labelling (VEPCASL) allows the selective labelling of blood water in different combinations of brain feeding arteries that can be combined in post-processing to yield vascular territory maps. The mechanism of VEPCASL was elucidated and optimised through simulations of the Bloch equations and phantom experiments, including its sensitivity to se- quence parameters, blood velocity and off-resonance effects. An implementation of the VEPCASL pulse sequence using an echo-planar imaging (EPI) readout was applied in healthy volunteers to enable optimisation of the post-labelling delay and choice of labelling plane position. Improvements to the signal-to-noise ratio (SNR) and motion-sensitivity were made through the addition of background suppression pulses and a partial-Fourier scheme. Exper- iments using a three-dimensional gradient and spin echo (3D-GRASE) readout were somewhat compromised by significant blurring in the slice direction, but showed potential for future work with a high SNR and reduced dropout arte- facts. The VEPCASL preparation was also applied to a dynamic 2D angiographic readout, allowing direct visualisation of collateral blood flow in the brain as well as a morphological and functional assessment of the major cerebral arteries. The application of a balanced steady-state free precession (bSSFP) readout signifi- cantly increased the acquisition efficiency, allowing the generation of dynamic 3D vessel-selective angiograms. A theoretical model of the dynamic angiographic signal was also derived, allowing quantification of blood flow through specified vessels, providing a significant advantage over qualitative x-ray based methods. Finally, these methods were applied to a number of patient groups, including those with vertebro-basilar disease, carotid stenosis and arteriovenous malfor- mation. These preliminary studies demonstrate that useful clinical information regarding collateral blood flow can be obtained with these techniques.
Download or read book Functional MRI written by Scott H. Faro and published by Springer Science & Business Media. This book was released on 2006-11-22 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: Functional magnetic resonance imaging (fMRI) measures quick, tiny metabolic changes that take place in the brain, providing the most sensitive method currently available for identifying, investigating, and monitoring brain tumors, stroke, and chronic disorders of the nervous system like multiple sclerosis, and brain abnormalities related to dementia or seizures. This overview explores experimental research design, outlines challenges and limitations of fMRI, provides a detailed neuroanatomic atlas, and describes clinical applications of fMRI in cognitive, sensory, motor, and pharmacological cases, translating research into clinical application.
Download or read book Contrast Enhanced Clinical Magnetic Resonance Imaging written by Val M. Runge and published by University Press of Kentucky. This book was released on 1997 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Progress in Brain Research written by J. P. Schadé and published by . This book was released on 1963 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adult Hydrocephalus written by Daniele Rigamonti and published by Cambridge University Press. This book was released on 2014-02-06 with total page 331 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides guidelines for managing this grossly underdiagnosed and undertreated condition, focusing on early detection and timely, effective interventions.
Download or read book The Cerebral Circulation written by Marilyn J. Cipolla and published by Biota Publishing. This book was released on 2016-07-28 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: This e-book will review special features of the cerebral circulation and how they contribute to the physiology of the brain. It describes structural and functional properties of the cerebral circulation that are unique to the brain, an organ with high metabolic demands and the need for tight water and ion homeostasis. Autoregulation is pronounced in the brain, with myogenic, metabolic and neurogenic mechanisms contributing to maintain relatively constant blood flow during both increases and decreases in pressure. In addition, unlike peripheral organs where the majority of vascular resistance resides in small arteries and arterioles, large extracranial and intracranial arteries contribute significantly to vascular resistance in the brain. The prominent role of large arteries in cerebrovascular resistance helps maintain blood flow and protect downstream vessels during changes in perfusion pressure. The cerebral endothelium is also unique in that its barrier properties are in some way more like epithelium than endothelium in the periphery. The cerebral endothelium, known as the blood-brain barrier, has specialized tight junctions that do not allow ions to pass freely and has very low hydraulic conductivity and transcellular transport. This special configuration modifies Starling's forces in the brain microcirculation such that ions retained in the vascular lumen oppose water movement due to hydrostatic pressure. Tight water regulation is necessary in the brain because it has limited capacity for expansion within the skull. Increased intracranial pressure due to vasogenic edema can cause severe neurologic complications and death.
Download or read book Acute Stroke Nursing written by Jane Williams and published by John Wiley & Sons. This book was released on 2013-05-07 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stroke is a medical emergency that requires immediate medical attention. With active and efficient nursing management in the initial hours after stroke onset and throughout subsequent care, effective recovery and rehabilitation is increased. Acute Stroke Nursing provides an evidence-based, practical text facilitating the provision of optimal stroke care during the primary prevention, acute and continuing care phases. This timely and comprehensive text is structured to follow the acute stroke pathway experienced by patients. It explores the causes, symptoms and effects of stroke, and provides guidance on issues such as nutrition, continence, positioning, mobility and carer support. The text also considers rehabilitation, discharge planning, palliative care and the role of the nurse within the multi-professional team. Acute Stroke Nursing is the definitive reference on acute stroke for all nurses and healthcare professionals wishing to extend their knowledge of stroke nursing. Evidence-based and practical in style, with case studies and practice examples throughout Edited and authored by recognised stroke nursing experts, clinicians and leaders in the field of nursing practice, research and education The first text to explore stroke management from UK and international perspectives, and with a nursing focus
Download or read book MR and CT Perfusion and Pharmacokinetic Imaging Clinical Applications and Theoretical Principles written by Roland Bammer and published by Lippincott Williams & Wilkins. This book was released on 2016-03-03 with total page 2558 pages. Available in PDF, EPUB and Kindle. Book excerpt: Essential reading for both clinicians and researchers, this comprehensive resource covers what you need to know about the basic principles of perfusion, as well as its many clinical applications. Broad coverage outlines the overarching framework that interlinks methods such as DSC, DCE, CTP, and ASL. International experts in the field demonstrate how perfusion and pharmacokinetic imaging can be effectively used to analyze medical conditions, helping you reach accurate diagnoses and monitor disease progression and response to therapy.
