Download or read book Developing High density Diffuse Optical Tomography for Neuroimaging written by Brian Richard White and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Clinicians who care for brain-injured patients and premature infants desire a bedside monitor of brain function. A decade ago, there was hope that optical imaging would be able to fill this role, as it combined fMRI's ability to construct cortical maps with EEG's portable, cap-based systems. However, early optical systems had poor imaging performance, and the momentum for the technique slowed. In our lab, we develop diffuse optical tomography (DOT), which is a more advanced method of performing optical imaging. My research has been to pioneer the in vivo use of DOT for advanced neuroimaging by (1) quantifying the advantages of DOT through both in silico simulation and in vivo performance metrics, (2) restoring confidence in the technique with the first retinotopic mapping of the visual cortex (a benchmark for fMRI and PET), and (3) creating concepts and methods for the clinical translation of DOT. Hospitalized patients are unable to perform complicated neurological tasks, which has motivated us to develop the first DOT methods for resting-state brain mapping with functional connectivity. Finally, in collaboration with neonatologists, I have extended these methods with proof-of-principle imaging of brain-injured premature infants. This work establishes DOT's improvements in imaging performance and readies it for multiple clinical and research roles.

Download or read book Diffuse Optical Tomography Methods for Imaging the Developing Brain written by Silvina Laura Ferradal and published by . This book was released on 2014 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diffuse optical imaging (DOI) is a portable imaging modality that provides the ability to perform early and continuous monitoring of brain function in infants. Its methodology overcomes many of the technical and logistical challenges of performing magnetic resonance imaging (MRI) investigations in neonates. However, standard DOI systems suffer from limitations such as low spatial resolution and contamination of hemodynamic signals originating from superficial tissue layers that affect the overall reliability of the optical measurements. Recent advances in the application of high-density diffuse optical tomography (HD-DOT) in adults have overcome most of these limitations by using high-density arrays of overlapping measurements that improve spatial resolution and brain specificity. My doctoral work has been focused on the development of HD-DOT methods for bedside neuroimaging in neonates. While HD-DOT enables image reconstructions with improved image quality, the design and implementation of high-density arrays for newborn infants involves challenges related to cap ergonomics and bulkiness of the fiber bundles. The first part of my dissertation demonstrates the feasibility of using a custom-built HD-DOT system with a limited field of view for imaging brain function in a clinical environment such as the neonatal intensive care unit (NICU). Using stimulus-driven paradigms such as visual stimulation and advanced imaging techniques such as resting state functional connectivity, I show that HD-DOT can perform functional mapping of the visual cortex in hospitalized infants. Resting state functional connectivity methods are particularly suited for studying hospitalized infants who cannot perform complex tasks. Accordingly, the second part of my dissertation was focused on the development of an extended field of view system for simultaneous functional connectivity DOT (fcDOT) mapping of multiple functional regions. In parallel with the hardware expansion, I developed techniques for realistic forward light modeling and spatial normalization that facilitate anatomical registration between different subjects and imaging modalities. The proposed techniques were validated in vivo against subject-matched functional MRI maps, the gold standard for functional neuroimaging. The strong spatial agreement between individual and group maps obtained for both modalities suggests that fcDOT provides satisfactory spatial localization and resolution for imaging neonates at the bedside. While in most cases it is desirable to use subject-specific structural images for accurate DOT reconstruction, this approach is not sufficient for portable applications. In the last part of my dissertation, I explored the feasibility of using anatomical atlases for forward light modeling. Quantitative comparisons with functional MRI show that atlas-based image reconstruction provides a viable approach to individual head modeling for HD-DOT when anatomical imaging is not available.

Download or read book High density Diffuse Optical Tomography During Passive Movie Viewing written by Andrew Kelsey Fishell and published by . This book was released on 2019 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Human neuroimaging techniques enable researchers and clinicians to non-invasively study brain function across the lifespan in both healthy and clinical populations. However, functional brain imaging methods such as functional magnetic resonance imaging (fMRI) are expensive, resource-intensive, and require dedicated facilities, making these powerful imaging tools generally unavailable for assessing brain function in settings demanding open, unconstrained, and portable neuroimaging assessments. Tools such as functional near-infrared spectroscopy (fNIRS) afford greater portability and wearability, but at the expense of cortical field-of-view and spatial resolution. High-Density Diffuse Optical Tomography (HD-DOT) is an optical neuroimaging modality directly addresses the image quality limitations associated with traditional fNIRS techniques through densely overlapping optical measurements. This thesis aims to establish the feasibility of using HD-DOT in a novel application demanding exceptional portability and flexibility: mapping disrupted cortical activity in chronically malnourished children. I first motivate the need for dense optical measurements of brain tissue to achieve fMRI-comparable localization of brain function (Chapter 2). Then, I present imaging work completed in Cali, Colombia, where a cohort of chronically malnourished children were imaged using a custom HD-DOT instrument to establish feasibility of performing field-based neuroimaging in this population (Chapter 3). Finally, in order to meet the need for age appropriate imaging paradigms in this population, I develop passive movie viewing paradigms for use in optical neuroimaging, a flexible and rich stimulation paradigm that is suitable for both adults and children (Chapter 4).

Download or read book Developing Diffuse Optical Tomography DOT for Neuroimaging of Speech Perception in People with Cochlear Implants written by Mahlega Hassanpour and published by . This book was released on 2015 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structured Illumination Diffuse Optical Tomography for Mouse Brain Imaging written by Matthew David Reisman and published by . This book was released on 2017 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: As advances in functional magnetic resonance imaging (fMRI) have transformed the study of human brain function, they have also widened the divide between standard research techniques used in humans and those used in mice, where high quality images are difficult to obtain using fMRI given the small volume of the mouse brain. Optical imaging techniques have been developed to study mouse brain networks, which are highly valuable given the ability to study brain disease treatments or development in a controlled environment. A planar imaging technique known as optical intrinsic signal (OIS) imaging has been a powerful tool for capturing functional brain hemodynamics in rodents. Recent wide field-of-view implementations of OIS have provided efficient maps of functional connectivity from spontaneous brain activity in mice. However, OIS requires scalp retraction and is limited to imaging a 2-dimensional view of superficial cortical tissues. Diffuse optical tomography (DOT) is a non-invasive, volumetric neuroimaging technique that has been valuable for bedside imaging of patients in the clinic, but previous DOT systems for rodent neuroimaging have been limited by either sparse spatial sampling or by slow speed. My research has been to develop diffuse optical tomography for whole brain mouse neuroimaging by expanding previous techniques to achieve high spatial sampling using multiple camera views for detection and high speed using structured illumination sources. I have shown the feasibility of this method to perform non-invasive functional neuroimaging in mice and its capabilities of imaging the entire volume of the brain. Additionally, the system has been built with a custom, flexible framework to accommodate the expansion to imaging multiple dynamic contrasts in the brain and populations that were previously difficult or impossible to image, such as infant mice and awake mice. I have contributed to preliminary feasibility studies of these more advanced techniques using OIS, which can now be carried out using the structured illumination diffuse optical tomography technique to perform longitudinal, non-invasive studies of the whole volume of the mouse brain.

Download or read book Frequency Domain High Density Diffuse Optical Tomography for Functional Brain Imaging written by Matthaios Doulgerakis and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Near infrared Diffuse Optical Brain Imaging Technique written by 莊競程 and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Super Pixel Diffuse Optical Tomography written by Karla Michelle Bergonzi and published by . This book was released on 2017 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical imaging has long held promise as a clinical, bedside neuroimaging tool; however, the performance has been lacking compared to functional Magnetic Resonance Imaging (fMRI), the gold standard of functional brain imaging. Recently, High-Density Diffuse Optical Tomography (HD-DOT) has matched image resolution with fMRI and has adapted an fMRI technique which assays cerebral function without requiring task performance, known as resting-state functional connectivity, for use with optical data. HD-DOT uses safe, near-infrared light delivered via optical fibers to the head to measure oxygenation changes in the brain. The system performance of HD-DOT has been validated using tasks and resting-state functional connectivity in healthy adults but has not yet transitioned to a bedside neuroimaging tool. The final limitations are ergonomic in nature, including large console sizes and heavy caps.In this dissertation, we utilize advances in CMOS camera sensor designs to improve the ergonomics of HD-DOT systems for use in clinical care settings. The primary advantage we are leveraging to improve HD-DOT ergonomics is the increased sensitivity of CMOS sensors compared to previously used detectors. This increased sensitivity allows for a reduction in the optical fiber diameters without compromising data quality. The reduced fiber diameters significantly decrease the weight of the cap, improving wearability. The secondary advantage of CMOS sensors are their small form factors which allow for a significantly reduced console size, improving the portability of the system. The disadvantage of CMOS sensors are the low dynamic ranges (DNR), which are 100-fold lower than the DNR necessary for HD-DOT neuroimaging. To combat this disadvantage, we have developed a Super Pixel HD-DOT (SP-DOT) algorithm which uses pixel binning and electronic noise reduction to meet the required specifications for HD-DOT neuroimaging. This dissertation reports the development, testing, and validation of the SP-DOT system. Collectively, this dissertation demonstrates that advanced SP-DOT offers a practical solution to imaging brain activity in the clinic with fMRI-comparable spatial resolution.As a preliminary investigation into the utility of HD-DOT in the clinic, we imaged acute stroke patients at the bedside using a first generation, APD-based HD-DOT system with large optical fibers. By optimizing the location of the cap, we were able to image key areas of the brain while maintaining system portability and moderate cap wearability. We had success collecting resting-state data from these acute stroke patients for use in functional connectivity analysis. We developed a "Similarity" metric for each stroke patient, which is a measure of how similar the stroke patients' connectivity maps are to a healthy cohort. This similarity metric is significantly reduced over the damaged hemisphere in stroke patients and also correlates with neurological impairment.

Download or read book Development of Diffuse Optical Tomography for Imaging the Brain written by Xuefeng Cheng and published by . This book was released on 2000 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Through simulations, we first show the inaccuracy of near-infrared spectroscopy (NIRS) in quantifying local perturbations in the absorption coefficient of turbid medium and showed that DOT is required for quantitative study of such local changes.

Download or read book Optical Methods and Instrumentation in Brain Imaging and Therapy written by Steen J. Madsen and published by Springer Science & Business Media. This book was released on 2012-11-13 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive up-to-date review of optical approaches used in brain imaging and therapy. It covers a variety of imaging approaches including diffuse optical imaging, laser speckle imaging, photoacoustic imaging and optical coherence tomography. A number of laser-based therapeutic techniques are reviewed, including photodynamic therapy, fluorescence guided resection and photothermal therapy. Fundamental principles and instrumentation are discussed for each imaging and therapeutic approach.

Download or read book High resolution Three D Diffuse Optical Tomography for Non invasive Functional Brain Imaging in the Sub centimeter Range written by and published by . This book was released on 2014 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Optical Imaging for Clinical Medicine written by Nicusor Iftimia and published by John Wiley & Sons. This book was released on 2011-04-27 with total page 641 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides students, teachers, researchers and clinicians with a strong and established source of information on advanced optical technologies that show real promise of being translated to clinical use.

Download or read book Handbook of Neurophotonics written by Francesco S. Pavone and published by CRC Press. This book was released on 2020-05-10 with total page 579 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Handbook of Neurophotonics provides a dedicated overview of neurophotonics, covering the use of advanced optical technologies to record, stimulate, and control the activity of the brain, yielding new insight and advantages over conventional tools due to the adaptability and non-invasive nature of light. Including 32 colour figures, this book addresses functional studies of neurovascular signaling, metabolism, electrical excitation, and hemodynamics, as well as clinical applications for imaging and manipulating brain structure and function. The unifying theme throughout is not only to highlight the technology, but to show how these novel methods are becoming critical to breakthroughs that will lead to advances in our ability to manage and treat human diseases of the brain. Key Features: Provides the first dedicated book on state-of-the-art optical techniques for sensing and imaging across at the cellular, molecular, network, and whole brain levels. Highlights how the methods are used for measurement, control, and tracking of molecular events in live neuronal cells, both in basic research and clinical practice. Covers the entire spectrum of approaches, from optogenetics to functional methods, photostimulation, optical dissection, multiscale imaging, microscopy, and structural imaging. Includes chapters that show use of voltage-sensitive dye imaging, hemodynamic imaging, multiphoton imaging, temporal multiplexing, multiplane microscopy, optoacoustic imaging, near-infrared spectroscopy, and miniature neuroimaging devices to track cortical brain activity.

Download or read book Model based High density Functional Diffuse Optical Tomography of Human Brain written by Yuxuan Zhan and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Functional diffuse optical tomography (fDOT) is an emerging functional neuroimaging technology that allows non-invasive imaging of human brain functions. The aims of this thesis are to enhance current understandings and knowledge of fDOT image quality and to improve on its imaging performance using a model-based approach. Specifically we have established a computationally efficient finite element method (FEM)-based routine to conduct MRI-guided fDOT simulation studies. Based on this framework, we have demonstrated that HD-fDOT is capable of imaging focal haemodynamic response up to 18 mm depth below the human scalp surface at 10 mm image resolution and localisation accuracy, allowing distinguishability of gyri. In addition, we also investigated the effects of uncertainty in the background tissue optical property on HD-fDOT image quality. Our multi-model comparative study has concluded that the use of a proposed homogeneous background absorption fitting scheme in HD-fDOT can minimise the chances of obtaining sub-optimal image quality due to uncertainty in background tissue optical properties. Finally we have addressed and resolved a regularisation problem in spectral fDOT that was previously not understood. Our proposed singular-decomposition-based regularisation method has been shown to reduce imaging crosstalk observed in both spectral and non-spectral fDOT.

Download or read book Diffuse Optical Tomography written by Huabei Jiang and published by CRC Press. This book was released on 2018-09-03 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by an authority involved in the field since its nascent stages, Diffuse Optical Tomography: Principles and Applications is a long-awaited profile of a revolutionary imaging method. Diffuse Optical Tomography (DOT) provides spatial distributions of intrinsic tissue optical properties or molecular contrast agents through model-based reconstruction algorithms using NIR measurements along or near the boundary of tissue. Despite the practical value of DOT, many engineers from electrical or applied mathematics backgrounds do not have a sufficient understanding of its vast clinical applications and portability value, or its uncommon advantages as a tool for obtaining functional, cellular, and molecular parameters. A collection of the author’s research and experience, this book fuses historical perspective and experiential anecdotes with fundamental principles and vital technical information needed to successfully apply this technology—particularly in medical imaging. This reference finally outlines how to use DOT to create experimental image systems and adapt the results of laboratory studies for use in clinical applications including: Early-stage detection of breast tumors and prostate cancer "Real-time" functional brain imaging Joint imaging to treat progressive diseases such as arthritis Monitoring of tumor response New contrast mechanisms and multimodality methods This book covers almost every aspect of DOT—including reconstruction algorithms based on nonlinear iterative Newton methods, instrumentation and calibration methods in both continuous-wave and frequency domains, and important issues of imaging contrast and spatial resolution. It also addresses phantom experiments and the development of various image-enhancing schemes, and it describes reconstruction methods based on contrast agents and fluorescence DOT. Offering a concise description of the particular problems involved in optical tomography, this reference illustrates DOT’s fundamental foundations and the principle of image reconstruction. It thoroughly explores computational methods, forward mathematical models, and inverse strategies, clearly illustrating solutions to key equations.

Download or read book Advanced Optical Methods for Brain Imaging written by Fu-Jen Kao and published by Springer. This book was released on 2018-05-14 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights the rapidly developing field of advanced optical methods for structural and functional brain imaging. As is known, the brain is the most poorly understood organ of a living body. It is indeed the most complex structure in the known universe and, thus, mapping of the brain has become one of the most exciting frontlines of contemporary research. Starting from the fundamentals of the brain, neurons and synapses, this book presents a streamlined and focused coverage of the core principles, theoretical and experimental approaches, and state-of-the-art applications of most of the currently used imaging methods in brain research. It presents contributions from international leaders on different photonics-based brain imaging modalities and techniques. Included are comprehensive descriptions of many of the technology driven spectacular advances made over the past few years that have allowed novel insights of the structural and functional details of neurons. The book is targeted at researchers, engineers and scientists who are working in the field of brain imaging, neuroscience and connectomics. Although this book is not intended to serve as a textbook, it will appeal to undergraduate students engaged in the specialization of brain imaging.

Download or read book New Horizons in Time Domain Diffuse Optical Spectroscopy and Imaging written by Yoko Hoshi and published by MDPI. This book was released on 2020-06-23 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jöbsis was the first to describe the in vivo application of near-infrared spectroscopy (NIRS), also called diffuse optical spectroscopy (DOS). NIRS was originally designed for the clinical monitoring of tissue oxygenation, and today it has also become a useful tool for neuroimaging studies (functional near-infrared spectroscopy, fNIRS). However, difficulties in the selective and quantitative measurements of tissue hemoglobin (Hb), which have been central in the NIRS field for over 40 years, remain to be solved. To overcome these problems, time-domain (TD) and frequency-domain (FD) measurements have been tried. Presently, a wide range of NIRS instruments are available, including commonly available commercial instruments for continuous wave (CW) measurements, based on the modified Beer–Lambert law (steady-state domain measurements). Among these measurements, the TD measurement is the most promising approach, although compared with CW and FD measurements, TD measurements are less common, due to the need for large and expensive instruments with poor temporal resolution and limited dynamic range. However, thanks to technological developments, TD measurements are increasingly being used in research, and also in various clinical settings. This Special Issue highlights issues at the cutting edge of TD DOS and diffuse optical tomography (DOT). It covers all aspects related to TD measurements, including advances in hardware, methodology, the theory of light propagation, and clinical applications.