Download or read book Assessment of Brain Function and Hemodynamics Using Magnetic Resonance Imaging written by Karthikeyan Kuppusamy and published by . This book was released on 1997 with total page 360 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 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 Implementation and Assessment of Novel Functional Hemodynamic MRI Measurements in the Brain for Evaluation of Disease and Treatment written by Adam Martin Winchell and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The characterization and quantification of cerebral hemodynamics can provide critical biological information of current physiology. Divergent hemodynamic processes can provide integral knowledge into different pathophysiologies and aid in the diagnosis and evaluation of treatment. A variety of different magnetic resonance (MR) imaging techniques were implemented to quantify cerebral hemodynamics in a diverse set of neurological conditions. The first study investigated the association of blood flow and blood volume of a diffuse intrinsic pontine glioma tumor by arterial spin labeling (ASL) and dynamic susceptibility weighted contrast MR as a predictive marker of survival. Higher tumor blood flow and maintenance of higher blood flow was associated with longer progression free survival. In the following study, ASL was used to evaluate the association of resting state perfusion and neurocognitive impairment in long-term survivors of pediatric acute lymphoblastic leukemia and Hodgkin lymphoma. Systematic differences in resting state perfusion and neurocognitive performance was observed between the cancer survivor groups. In the last few studies, a variety of different MR techniques were implemented to investigate the hemodynamic properties of Sickle cell disease (SCD). Susceptibility weighed imaging (SWI) was used to investigate difference in the cerebral venous vascular system integrity between SCD patients and healthy controls. A segmentation procedure was introduced to quantify the normalized visible venous volume (NVVV). The study showed that SCD effects SWI venous conspicuity by having a lower NVVV with a global isointense venous contrast. A follow-up study improved the accuracy of the NVVV quantification by removing hypointese arterial vessel contamination. This new segmentation framework combined information from SWI and MR angiography. In the final study, intracranial blood velocity measurements made by MRI and transcranial Doppler ultrasound were compared in a cohort of SCD patients. Excessive intracranial blood velocity is a clinical indicator of elevated stroke risk in SCD patients. Blood velocities correlated well between the different modalities, however, MR systematically underestimated the blood velocity. The ability to noninvasively image, quantify, and monitor biological processed represents a powerful diagnostic toolkit for physiological evaluation. Characterizing cerebral hemodynamics only represents a small but vital tool for the future of medicine.
Download or read book Functional Magnetic Resonance Imaging written by Rakesh Sharma and published by BoD – Books on Demand. This book was released on 2012-05-09 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Functional Magnetic Resonance Imaging - Advanced Neuroimaging Applications" is a concise book on applied methods of fMRI used in assessment of cognitive functions in brain and neuropsychological evaluation using motor-sensory activities, language, orthographic disabilities in children. The book will serve the purpose of applied neuropsychological evaluation methods in neuropsychological research projects, as well as relatively experienced psychologists and neuroscientists. Chapters are arranged in the order of basic concepts of fMRI and physiological basis of fMRI after event-related stimulus in first two chapters followed by new concepts of fMRI applied in constraint-induced movement therapy; reliability analysis; refractory SMA epilepsy; consciousness states; rule-guided behavioral analysis; orthographic frequency neighbor analysis for phonological activation; and quantitative multimodal spectroscopic fMRI to evaluate different neuropsychological states.
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 Proceedings of the International School on Magnetic Resonance and Brain Function XII Workshop written by Federico Giove and published by Frontiers Media SA. This book was released on 2018-09-06 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last thirty years, Magnetic Resonance has generated a wide revolution in biomedical research and in medical imaging in general. More recently, the "in vivo" studies of the human brain were extended by new original ways to the dynamic study of function and metabolism of the human brain. The enormous interest in expanding the investigation of the brain is emphasizing the search for new NMR methods capable of extracting information of so-far obscure aspects of the brain function. In fact, many quantitative approaches have been proposed in order to complement the information obtained by functional MRI, and several multimodal and multiparametric approaches have been developed to exploit the information, either functional or structural, made available by the flexible contrast generation typical of MRI, and to combine it with complementary information. The XII workshop of the International School on Magnetic Resonanceand Brain Function, held in Erice between 17 April and 6 May, 2016, was specially devoted to novel approaches aimed at better structural characterization of brain diseases, and at investigating frontiers MRI approaches to better understand the brain function. The papers included in this eBook offer a broad overview of the subjects covered during the Workshop, including applications of multiparametric MRI to neurological diseases, multimodal combination of MRI with electrophysiology, advanced methods for the investigation of brain networks and of brain physiology, and perspectives towards brain state reading.
Download or read book Cerebral MR Perfusion Imaging written by A. Gregory Sorensen and published by Thieme. This book was released on 2000 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will familiarize the reader with the basic principles of perfusion MR imaging. Relevant technical aspects, contrast agents, and the postprocessing of images are presented, and imaging protocols are provided. Dedicated software for personal use on the postprocessing of images is provided on a CD-ROM containing hundreds of images and movie clips that demonstrate all concepts. In addition to the technical details of acquisition and postprocessing, numerous examples of the application of these tools in the clinical setting are also shown. In particular, the book includes a discussion of the role of perfusion MRI in the current evaluation of cerebrovascular disease, including an integrative approach using diffusion in conjunction with perfusion imaging. This text covers: all relevant technical aspects of perfusion MR imaging imaging protocols application of these tools in a clinical setting integration of diffusion imaging with perfusion imaging for enhanced diagnostic capabilities Also addressed are the role of perfusion MRI in the assessment of cerebral neoplasia, challenges and opportunities for treatment that tumors present, and the particular strengths of perfusion MRI, such as its relatively high resolution and possible microvascular specificity. For both newcomers and experienced practitioners, this is a nuts-and-bolts description of an important new technique.
Download or read book Assessment of Cerebral Hemodynamics by Deconvolution with Dynamic Susceptibility Contrast magnetic Resonance Imaging written by Francesca Zanderigo and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hemodynamic Measurements and Modeling for Functional Magnetic Resonance Imaging written by Reswanul Kabir Khan and published by . This book was released on 2014 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: In imaging, short wavelength (high-frequency) particles scattered from targets typically yield greater spatial resolutions than longer wavelengths. X-Rays, for example are typically within 2 orders of magnitude of a nanometer wavelength to achieve desired resolutions for medical imaging. Although better for imaging, this poses a health risk for subjects as ionizing radiation and this limits its use. Functional Magnetic Resonance Imaging (fMRI) avoids this issue by using radiation of much larger wavelengths, 4.8 m (62.5 MHz), that are relatively harmless. Instead of scattering, these photons are used to excite protons between spin-states in an external magnetic field. Magnetization relaxation rates and dephasing as a function of space and time are then measured to reconstruct images. This dissertation develops experimental methods to understand and interpret the biophysical underpinnings of fMRI in terms of blood flow and oxygen concentration changes. In neuroscience, fMRI may be used to deduce brain activity. Brain activity is a general term related to neuronal firing rate, which metabolizes oxygen. Deoxygenated blood increases proton spin dephasing. This is the physical mechanism that ultimately yields contrast in the fMRI signal. This is known as Blood-Oxygen Level Dependent (BOLD) contrast. A critical piece of information in this process, hemodynamics, is the dynamics of cerebral (brain) oxygen concentrations in relation to blood flow. The hemodynamics of BOLD contrast fMRI and its relation to brain activity is vital. In this dissertation, I have classified hemodynamic data as a function of space and time in cerebral cortex as well as testing a rudimentary hemodynamic model. I have taken fMRI measurements in three human subjects to identify spatial and temporal hemodynamic trends in brain. Furthermore, I've analyzed laser-speckle imaging in three subjects to identify spatiotemporal trends in blood speed. The final portion of this dissertation relates developments of a hemodynamic model of BOLD.
Download or read book Brain Imaging and Hemodynamic Models written by Thomas Deneux and published by LAP Lambert Academic Publishing. This book was released on 2011-01 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Function Magnetic Resonance Imaging (fMRI) provides recording of humain brain activity at high spatial resolution. It measures the changes in blood dynamics related to the neural activity. While most fMRI analysis methods assume a very simple linear relationship between neural activity and this hemodynamic response, it is not clear whether actually more physiologically-based models are needed to extract exact information, or allow complex analysis such as the fusion between fMRI and EEG data. This is the general question asked in this book. On the one hand, a new methodology is set for the analysis of fMRI data and for EEG-fMRI fusion, based on physiological models. On the other hand, this methodology, and more experimental investigations based on Optical Imaging recording of the cerebral blood flow, volume, and oxygenation, are used to determine which models should be used, and whether their linear approximation is acceptable. The critical physiological question treated in this work, but also the rich developments of algorithms, such as fMRI-EEG fusion and red blood cell tracking, make it an important contribution to brain imaging science.
Download or read book Optical Imaging of Brain Function and Metabolism 2 written by Arno Villringer and published by Boom Koninklijke Uitgevers. This book was released on 1997-06-30 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covers the latest developments in optical imaging of the brain.
Download or read book Design and Statistical Analysis of FMRI Experiments to Assess Human Brain Hemodynamic Responses written by Marc Alexander Burock and published by . This book was released on 1998 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book MRI Methods for Cerebrovascular Hemodynamics Assessment written by Leonardo A. Rivera and published by . This book was released on 2017 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intracranial vascular hemodynamics and vascular architecture are modified in a wide array of diseases, including tumors, stroke, and varying forms of dementia. Non-invasive methods capable of quantitatively assessing cerebrovascular disease are highly desirable. Magnetic resonance imaging (MRI) enables non-invasive quantitative assessment of cerebral hemodynamics and structure. Within this framework, the work in this thesis describes and applies innovative approaches to characterize hemodynamics in the cerebral vasculature using quantitative MRI. Additionally, these methods are validated and exhibited in-vivo. To assess vascular hemodynamics in relatively large arteries and veins a 4D flow MRI approach was used. This method enables both volumetric angiographic and quantitative assessment of blood flow velocities in a single acquisition with full volumetric coverage and sub millimeter resolution. 4D flow MRI was applied to healthy and pathological populations of individuals including: healthy younger and older adults, Alzheimer's disease (AD), mild cognitively impaired (MCI) and dural arteriovenous fistula (DAVF) patients. Targeted blood flow derived measurements, such as blood flow rates, pulsatility and resistivity, area, flow directionality, and pressure gradients were quantified. To assess small vessels and brain parenchyma tissue hemodynamics T1 and T2* mapping techniques were explored using ferumoxytol enhanced MRI. In addition, time-resolved T2* ferumoxytol enhanced MRI was implemented. With these approaches small vessel pulsatility and cerebral blood volume (CBV) were successfully characterized in gray and white matter tissues in a cohort of healthy volunteers.
Download or read book Assessment of Regional Hemodynamics and Metabolism in Rat Brain by in Vivo Nuclear Magnetic Resonance written by Dewan Syed Fahmeed Hyder and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantitative Measurements of Cerebral Hemodynamics Using Magnetic Resonance Imaging written by Amit Mehndiratta and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cerebrovascular Ultrasound written by Michael G. Hennerici and published by Cambridge University Press. This book was released on 2001-10-25 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive text covers the fundamentals and clinical applications of cerebrovascular ultrasound in all ages.
