Download or read book A Navigator based Rigid Body Motion Correction for Magnetic Resonance Imaging written by Marcus Görge Ullisch and published by . This book was released on 2012 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Motion Correction in MR written by Andre van der Kouwe and published by Academic Press. This book was released on 2022-10-28 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt: Motion Correction in MR: Correction of Position, Motion, and Dynamic Changes, Volume Eight provides a comprehensive survey of the state-of-the-art in motion detection and correction in magnetic resonance imaging and magnetic resonance spectroscopy. The book describes the problem of correctly and consistently identifying and positioning the organ of interest and tracking it throughout the scan. The basic principles of how image artefacts arise because of position changes during scanning are described, along with retrospective and prospective techniques for eliminating these artefacts, including classical approaches and methods using machine learning. Internal navigator-based approaches as well as external systems for estimating motion are also presented, along with practical applications in each organ system and each MR modality covered. This book provides a technical basis for physicists and engineers to develop motion correction methods, giving guidance to technologists and radiologists for incorporating these methods in patient examinations. Provides approaches for correcting scans prospectively and retrospectively Shows how motion and secondary effects such as field changes manifest in MR scans as artifacts and subtle biases in quantitative research Gives methods for measuring motion and associated field changes, quantifying motion and judging the accuracy of the motion and field estimates

Download or read book Real time Measurement and Correction of 3D Rigid Body Motion in Magnetic Resonance Imaging written by Andreu Francesc Torre Costa and published by . This book was released on 2004 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Motion Artifact Reduction in Steady state Magnetic Resonance Imaging written by Richard Reeve Ingle and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic resonance imaging (MRI) is a powerful medical imaging modality that offers excellent soft-tissue contrast and numerous contrast-generation mechanisms. However, due to the relatively low signal-to-noise ratio (SNR) of MRI, many volumetric and high-resolution imaging techniques require long acquisition times yielding an increased sensitivity to motion. In many cardiac MRI applications, one of the most significant challenges is the reduction of motion artifacts caused by cardiac and respiratory motion. In these applications, a combination of SNR-efficient balanced steady-state free precession (bSSFP) pulse sequences, high-temporal-resolution motion tracking acquisitions, and retrospective motion correction algorithms are commonly employed to mitigate motion artifacts. Despite recent advances in steady-state pulse sequence development, navigator motion tracking acquisitions, and motion correction algorithms, motion artifact reduction continues to be a significant challenge for many cardiac MRI applications. A novel class of perturbed steady-state free precession (SSFP) pulse sequences is developed and analyzed, yielding new forms of steady-state image contrast. These sequences utilize alternating perturbations of sequence parameters such as the repetition time (TR) and flip angle to produce oscillating steady-state frequency responses. Large oscillations of the signal magnitude and phase occur at specific off-resonant frequencies, and the combination of these signals can yield spectrally selective image contrast. Applications are demonstrated for retrospective motion correction using cardiac fat navigator acquisitions in free-breathing whole-heart cardiac MRI and for positive-contrast imaging of superparamagnetic iron-oxide nanoparticles. The bSSFP pulse sequence is widely used in cardiac imaging due to its high signal per unit time and excellent blood-myocardial contrast. A drawback of this pulse sequence is the generation of bright signal from fat, which can lead to unwanted image artifacts. Alternating repetition time (ATR) SSFP is a recently developed sequence that generates fat-suppressed steady-state contrast, but it requires the addition of an unused time interval every repetition, making it less time efficient than bSSFP. A small modification to the ATR pulse sequence is proposed to enable the acquisition of a one-dimensional self-gating signal during this unused time interval. The self-gating signals are used for retrospective cardiac triggering in breath-held cardiac cine imaging, and the proposed sequence is evaluated in volunteer and patient populations. The resulting ECG-free self-gated images have no statistically significant differences compared with conventional ECG-gated images. The proposed sequence also yields robust suppression of epicardial fat compared with standard bSSFP cardiac cine imaging. In coronary MR angiography (CMRA), high-resolution, whole-heart acquisitions are typically required for visualization of the relatively small coronary vasculature. These acquisitions require long scan times that are carried out during free breathing, which can lead to severe ghosting and blurring artifacts without motion compensation. A nonrigid retrospective motion correction technique is proposed for motion artifact reduction in image-navigated CMRA. The technique reconstructs a bank of motion-compensated CMRA images using many candidate motion estimates derived from navigator images acquired throughout the scan. A metric-based autofocusing approach is used to automatically generate a final nonrigid-motion-corrected image from this bank of images. The proposed technique is evaluated in volunteer and patient studies, leading to improvements in vessel sharpness and image quality compared with rigid-body translational motion correction. These new steady-state pulse sequences, motion tracking acquisitions, and nonrigid reconstruction techniques address several of the challenges to cardiac MRI, enabling the reduction of motion artifacts and improvement of image quality.

Download or read book A Linear Systems Approach Towards the Reduction of Non rigid Body Motion Artifacts in Magnetic Resonance Spectroscopic Imaging written by Nandini Rajan and published by . This book was released on 1995 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book In Vivo High resolution Magnetic Resonance Imaging written by Joelle Barral and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic resonance imaging is a powerful, non-invasive modality that provides excellent soft-tissue contrast, but it suffers from a relatively low signal-to-noise ratio and is inherently prone to artifacts. Although technological progress over the last few decades has dramatically enhanced the resolution and quality of magnetic resonance images, specific clinical challenges highlight the need for further improvements. First, patients with peripheral arterial disease are at high risk for developing skin ulcers, which are often detected at a late stage, when amputation is the only treatment option. High-resolution imaging might detect changes in skin early enough to enable alternative treatments. Second, higher-resolution larynx imaging is highly desirable for the exact assessment of cartilage invasion, which is a critical step in cancer staging and in the selection of the appropriate treatment. High-resolution skin and larynx magnetic resonance imaging poses specific engineering challenges. The resolution of magnetic resonance images is first hampered by insufficient signal-to-noise ratio. Dedicated surface coils and/or higher field strengths overcome this limitation. Receive-only and transmit/receive 1-inch-diameter coils are shown to be suitable for skin imaging at 1.5 T, 3 T, and 7 T, and a dedicated three-channel array for larynx imaging provides a dramatic increase in resolution over the conventionally used 8-channel neurovascular array. The next engineering challenge involves eliminating artifacts from high-resolution images. Chemical shift artifacts are a concern in skin imaging, especially at higher field strengths, because the hypodermis is a fat layer. A multi-echo sequence is introduced that separates fat and water and provides good signal-to-noise ratio for all skin layers. Motion artifacts affect both skin and larynx images. In skin, where motion is usually rigid-body, navigator-based motion correction proves effective, and navigators can be integrated into the multi-echo sequence that separates fat and water. In larynx, where motion is complex, a new real-time algorithm combining a reacquisition strategy with navigator-based motion correction accounts for the different types of motion. One additional concern with skin imaging at higher field strengths is the increase in the spin-lattice relaxation time T1, which compromises the signal-to-noise ratio. Robust T1 mapping requires the use of a 4-parameter model. A novel nonlinear Least-Squares algorithm reduces the complex minimization problem to a straightforward 1D search, making the fitting procedure much faster. T1 mapping performed in skin at 1.5 T, 3 T, and 7 T shows that the increase in T1 slightly attenuates the benefits of higher field strengths but does not offset them.

Download or read book Brain Mapping written by and published by Academic Press. This book was released on 2015-02-14 with total page 2668 pages. Available in PDF, EPUB and Kindle. Book excerpt: Brain Mapping: A Comprehensive Reference, Three Volume Set offers foundational information for students and researchers across neuroscience. With over 300 articles and a media rich environment, this resource provides exhaustive coverage of the methods and systems involved in brain mapping, fully links the data to disease (presenting side by side maps of healthy and diseased brains for direct comparisons), and offers data sets and fully annotated color images. Each entry is built on a layered approach of the content – basic information for those new to the area and more detailed material for experienced readers. Edited and authored by the leading experts in the field, this work offers the most reputable, easily searchable content with cross referencing across articles, a one-stop reference for students, researchers and teaching faculty. Broad overview of neuroimaging concepts with applications across the neurosciences and biomedical research Fully annotated color images and videos for best comprehension of concepts Layered content for readers of different levels of expertise Easily searchable entries for quick access of reputable information Live reference links to ScienceDirect, Scopus and PubMed

Download or read book Fat Navigators Based Retrospective Motion Correction Strategies for Brain Magnetic Resonance Imaging written by Frédéric Gretsch and published by . This book was released on 2020 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mots-clés de l'auteur: MRI ; Ultra-high field ; Navigators ; Motion correction ; Field fluctuation correction ; Structural Imaging.

Download or read book Prospective Motion Correction with Chemically Selective Spherical Navigator Echoes for Functional Magnetic Resonance Imaging written by Narter Ari and published by . This book was released on 2004 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Detection and Correction of Patient Motion in Magnetic Resonance Imaging written by Murat Aksoy and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the sequential nature of magnetic resonance imaging (MRI) data acquisition, correction of image artifacts originating from involuntary patient motion is essential for reliable diagnostic quality. Especially during MRI scans of certain patient populations such as children, elderly or patients with certain medical conditions (e.g. stroke, Parkinson's), motion correction methods must be incorporated into the MR imaging protocol for adequate image quality. With increased demands for higher resolution or time-resolved examinations (e.g. functional MRI), examination times also increase and even willing patients might have trouble staying still during the course of the examination. The first part of this thesis provides a method for retrospective correction of head motion artifacts using a multi-shot spiral-in \ & out readout and parallel-imaging based iterative image reconstruction. The spiral-in part provided a low resolution image that was used for measurement of head motion. Due to rotational motion, locally undersampled areas appear in MR acquisition space (i.e., k-space), which violate the Nyquist theorem and cause artifacts even after motion correction. These artifacts were addressed through the data redundancy provided by multiple receiver channels that is present in modern receiver coils and an iterative conjugate-gradient based reconstruction. This method was then applied to diffusion tensor imaging (DTI) with multi-shot readout. Since DTI uses directional gradients to encode diffusion, rotational motion causes the image contrast to change, and it becomes incorrect to combine data with varying diffusion encodings on them. To address this issue, a non-linear conjugate gradient based reconstruction is presented and it is shown that this method provided more accurate description of white matter pathways compared to traditional methods. In the second part of this thesis, a prospective motion correction system using an optical tracking device is presented. Such systems are preferable compared to retrospective navigator-based methods due to various reasons, such as ability to perform motion correction independent of the MR data acquisition and immunity to spin history effects. The system proposed used a single camera mounted on the head coil and a self-encoded checkerboard marker mounted on the patient's forehead. Results on structural and diffusion imaging revealed that prospective motion correction outperforms retrospective navigator-based schemes. In the last part of the thesis, entropy-based retrospective autofocusing was used in combination with motion data obtained from prospective tracking to remove residual motion artifacts in the images. This method was especially useful for removing errors caused by inaccurate cross-calibration between the scanner and camera frame-of-references. It was also shown that prospective tracking can be the enabling technology for autofocusing in 3D acquisitions.

Download or read book Quantitative MRI of the Brain written by Mara Cercignani and published by CRC Press. This book was released on 2018-01-12 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: Building on the success of the first edition of this book, the winner of the 2004 British Medical Association Radiology Medical Book Competition, Quantitative MRI of the Brain: Principles of Physical Measurement gives a unique view on how to use an MRI machine in a new way. Used as a scientific instrument it can make measurements of a myriad of physical and biological quantities in the human brain and body. For each small tissue voxel, non-invasive information monitors how tissue changes with disease and responds to treatment. The book opens with a detailed exposition of the principles of good practice in quantification, including fundamental concepts, quality assurance, MR data collection and analysis and improved study statistical power through minimised instrumental variation. There follow chapters on 14 specific groups of quantities: proton density, T1, T2, T2*, diffusion, advanced diffusion, magnetisation transfer, CEST, 1H and multi-nuclear spectroscopy, DCE-MRI, quantitative fMRI, arterial spin-labelling and image analysis, and finally a chapter on the future of quantification. The physical principles behind each quantity are stated, followed by its biological significance. Practical techniques for measurement are given, along with pitfalls and examples of clinical applications. This second edition of this indispensable 'how to' manual of quantitative MR shows the MRI physicist and research clinician how to implement these techniques on an MRI scanner to understand more about the biological processes in the patient and physiological changes in healthy controls. Although focussed on the brain, most techniques are applicable to characterising tissue in the whole body. This book is essential reading for anyone who wants to use the gamut of modern quantitative MRI methods to measure the effects of disease, its progression, and its response to treatment. Features: The first edition was awarded the book prize for Radiology by the British Medical Association in 2004 Written by an authority in the field: Professor Tofts has an international reputation for quantification in MRI Gives specific ‘how to’ information for implementation of MRI measurement sequence techniques

Download or read book Issues in Medical Lasers Imaging and Devices Research and Application 2013 Edition written by and published by ScholarlyEditions. This book was released on 2013-05-01 with total page 567 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Medical Lasers, Imaging, and Devices Research and Application: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Medical Ultrasonography. The editors have built Issues in Medical Lasers, Imaging, and Devices Research and Application: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Medical Ultrasonography in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Medical Lasers, Imaging, and Devices Research and Application: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Advanced Neuro MR Techniques and Applications written by In-Young Choi and published by Academic Press. This book was released on 2021-11-17 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Neuro MR Techniques and Applications gives detailed knowledge of emerging neuro MR techniques and their specific clinical and neuroscience applications, showing their pros and cons over conventional and currently available advanced techniques. The book identifies the best available data acquisition, processing, reconstruction and analysis strategies and methods that can be utilized in clinical and neuroscience research. It is an ideal reference for MR scientists and engineers who develop MR technologies and/or support clinical and neuroscience research and for high-end users who utilize neuro MR techniques in their research, including clinicians, neuroscientists and psychologists. Trainees such as postdoctoral fellows, PhD and MD/PhD students, residents and fellows using or considering the use of neuro MR technologies will also be interested in this book. Presents a complete reference on advanced Neuro MR Techniques and Applications Edited and written by leading researchers in the field Suitable for a broad audience of MR scientists and engineers who develop MR technologies, as well as clinicians, neuroscientists and psychologists who utilize neuro MR techniques in their research

Download or read book Simulation and Correction of Rigid Body Motion in Medical Imaging written by Patrick Hucker and published by . This book was released on 2022* with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hybrid PET MR Neuroimaging written by Ana M. Franceschi and published by Springer Nature. This book was released on 2021-11-30 with total page 848 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book serves as a reference and comprehensive guide for PET/MR neuroimaging. The field of PET/MR is rapidly evolving, however, there is no standard resource summarizing the vast information and its potential applications. This book will guide neurological molecular imaging applications in both clinical practice and the research setting. Experts from multiple disciplines, including radiologists, researchers, and physicists, have collaborated to bring their knowledge and expertise together. Sections begin by covering general considerations, including public health and economic implications, the physics of PET/MR systems, an overview of hot lab and cyclotron, and radiotracers used in neurologic PET/MRI. There is then coverage of each major disease/systemic category, including dementia and neurodegenerative disease, epilepsy localization, brain tumors, inflammatory and infectious CNS disorders, head and neck imaging, as well as vascular hybrid imaging. Together, we have created a thorough, concise and up-to-date textbook in a unique, user-friendly format. This is an ideal guide for neuroradiologists, nuclear medicine specialists, medical physicists, clinical trainees and researchers.

Download or read book Motion Correction in Magnetic Resonance Imaging Using the Signal of Free Induction Decay written by Maryna Volodimirivna Waszak and published by . This book was released on 2016 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mots-clés de l'autrice: structural MRI ; FID navigator ; motion detection ; motion correction.

Download or read book Acquisition and Processing Techniques for Image Based Prospective Motion Correction in Magnetic Resonance Imaging written by Daniel Christopher Hoinkiss and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: