Development Of High Speed High Resolution Magnetic Resonance Imaging And Tagging Techniques
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Development Of High Speed High Resolution Magnetic Resonance Imaging And Tagging Techniques
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Author : Scott B. Reeder
language : en
Publisher:
Release Date : 1993
Development Of High Speed High Resolution Magnetic Resonance Imaging And Tagging Techniques written by Scott B. Reeder and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with categories.
Masters Theses In The Pure And Applied Sciences
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Author : Wade H. Shafer
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Masters Theses In The Pure And Applied Sciences written by Wade H. Shafer and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 39 (thesis year 1994) a total of 13,953 thesis titles from 21 Canadian and 159 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 39 reports theses submitted in 1994, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.
Application Tailored Accelerated Magnetic Resonance Imaging Methods
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Author : Ziwu Zhou
language : en
Publisher:
Release Date : 2018
Application Tailored Accelerated Magnetic Resonance Imaging Methods written by Ziwu Zhou and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Magnetic resonance imaging (MRI) is a powerful diagnostic medical imaging technique that provides very high spatial resolution. By manipulating the signal evolution through careful imaging sequence design, MRI can generate a wide range of soft-tissue contrast unique to individual application. However, imaging speed remains an issue for many applications. In order to increase scan output without compromising the image quality, the data acquisition and image reconstruction methods need to be designed to fit each application to achieve maximum efficiency. This dissertation concerns several application-tailored accelerated imaging methods through improved sequence design, efficient k-space traverse, as well as tailored image reconstruction algorithm, all together aiming to exploit the full potential of data acquisition and image reconstruction in each application. The first application is ferumoxtyol-enhanced 4D multi-phase cardiovascular MRI on pediatric patients with congenital heart disease. By taking advantage of the high signal-to-noise ratio (SNR) results from contrast enhancement, we introduced two methods to improve the scan efficiency with maintained clinical utility: one with reduced scan time and one with improved temporal resolution. The first method used prospective Poisson-disc under-sampling in combination with graphics processing unit accelerated parallel imaging and compressed sensing combined reconstruction algorithm to reduce scan time by approximately 50% while maintaining highly comparable image quality to un-accelerated acquisition in a clinically practical reconstruction time. The second method utilized a motion weighted reconstruction technique to increase temporal resolution of acquired data, and thus permits improved cardiac functional assessment. Compared with existing acceleration method, the proposed method has nearly three times lower computation burden and six times faster reconstruction speed, all with equal image quality. The second application is noncontrast-enhanced 4D intracranial MR angiography with arterial spin labeling (ASL). Considering the inherently low SNR of ASL signal, we proposed to sample k-space with the efficient golden-angle stack-of-stars trajectory and reconstruct images using compressed sensing with magnitude subtraction as regularization. The acquisition and reconstruction strategy in combination produces images with detailed vascular structures and clean background. At the same time, it allows a reduced temporal blurring delineation of the fine distal arteries when compared with the conventional k-space weighted image contrast (KWIC) reconstruction. Stands upon on this, we further developed an improved stack-of-stars radial sampling strategy for reducing streaking artifacts in general volumetric MRI. By rotating the radial spokes in a golden angle manner along the partition-encoding direction, the aliasing pattern due to under-sampling is modified, resulting in improved image quality for gridding and more advanced reconstruction methods. The third application is low-latency real-time imaging. To achieve sufficient frame rate, real-time MRI typically requires significant k-space under-sampling to accelerate the data acquisition. At the same time, many real-time application, such as interventional MRI, requires user interaction or decision making based on image feedback. Therefore, low-latency on-the-fly reconstruction is highly desirable. We proposed a parallel imaging and convolutional neural network combined image reconstruction framework for low-latency and high quality reconstruction. This is achieved by compacting gradient descent steps resolved from conventional parallel imaging reconstruction as network layers and interleaved with convolutional layers in a general convolutional neural network. Once all parameters of the network are determined during the off-line training process, it can be applied to unseen data with less than 100ms reconstruction time per frame, while more than 1s is usually needed for conventional parallel imaging and compressed sensing combined reconstruction.
Visualizing Chemistry
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Author : National Research Council
language : en
Publisher: National Academies Press
Release Date : 2006-06-01
Visualizing Chemistry written by National Research Council and has been published by National Academies Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006-06-01 with Science categories.
Scientists and engineers have long relied on the power of imaging techniques to help see objects invisible to the naked eye, and thus, to advance scientific knowledge. These experts are constantly pushing the limits of technology in pursuit of chemical imagingâ€"the ability to visualize molecular structures and chemical composition in time and space as actual events unfoldâ€"from the smallest dimension of a biological system to the widest expanse of a distant galaxy. Chemical imaging has a variety of applications for almost every facet of our daily lives, ranging from medical diagnosis and treatment to the study and design of material properties in new products. In addition to highlighting advances in chemical imaging that could have the greatest impact on critical problems in science and technology, Visualizing Chemistry reviews the current state of chemical imaging technology, identifies promising future developments and their applications, and suggests a research and educational agenda to enable breakthrough improvements.
Fast Dynamic Magnetic Resonance Imaging Using Sparse Recovery Methods And Novel Signal Encoding Formulations
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Author : Vimal Singh
language : en
Publisher:
Release Date : 2015
Fast Dynamic Magnetic Resonance Imaging Using Sparse Recovery Methods And Novel Signal Encoding Formulations written by Vimal Singh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Magnetic resonance imaging (MRI) is a non-invasive imaging modality that provides excellent soft tissue contrast without using ionizing radiations. These qualities/properties make MRI the preferred imaging modality for critical organs like heart and brain. Over the past decade, the advancement in hardware and image reconstruction algorithms has led to substantial improvements in MRI in terms of imaging speeds, quality and reliability. However, MRI speeds need to be further improved while retaining/maintaining the image quality given that the emerging medical diagnostic procedures are increasingly relying on detailed characterization of physiological functions that evolve on time scales too fast to be captured using conventional MRI methods. This dissertation starts with presenting a sparse signal recovery based fast MRI method. This method synergistically combines a data redundancy scheme for high frequency details with a novel and physically realizable MR signal encoding formulation. The new signal encoding formulation uses clinically deployed tagging radio frequency pulses to mix information in the spatial frequency domain prior to acquisition. Thus, the new formulation leads to a more uniform coverage of spatial frequency information even at high accelerations. The synergistic combination of image-detail redundancy encoding with tagging based signal encoding allows recovery of edges and fine structures with unprecedented quality. Next, this dissertation evaluates the use of fast spiral trajectories for high spatial resolution functional imaging of human superior colliculus. Gradient efficient and motion-robust spiral trajectories are used to keep fMRI scan durations short. . However, high resolution imaging of human subcortical structures using these trajectories is limited due to the weak functional responses of SC structures and also low signal-to-noise ratio associated with small voxels. To improve the functional sensitivity of spiral trajectories, dual echo variants are used. Combination of two echoes of the dual-echo variants reduces noise and thereby improves the functional sensitivity of high resolution fMRI. Lastly, this dissertation presents a novel formulation for fast dynamic MRI which combines the generic linear dynamical system model with sparse recovery techniques. Specifically, the formulation uses a known prior spatio-temporal model to predict the underlying image and uses sparse recovery techniques to recover the residual image. The spatio-temporal evolution model inherently encodes for coupled data redundancies in the spatial- and temporal-dimensions. Also, the generalizability of the formulation in choosing the evolution model allows it to be applicable to various physiological functions.
Development Of Multi Parametric High Field Magnetic Resonance Imaging Techniques For Improved Characterization Of Prostate Cancer
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Author : Albert Chen
language : en
Publisher:
Release Date : 2006
Development Of Multi Parametric High Field Magnetic Resonance Imaging Techniques For Improved Characterization Of Prostate Cancer written by Albert Chen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
The multi-parameric approach of acquiring different and unique MR data to characterize prostate cancer developed in this work may increase the usefulness and significance of MR prostate exam for the clinical management of prostate cancer.
Development Of Quantitative Fast Imaging With Steady State Free Precession Fisp Techniques For High Field Preclinical Magnetic Resonance Imaging
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Author : Ying Gao (Gao)
language : en
Publisher:
Release Date : 2017
Development Of Quantitative Fast Imaging With Steady State Free Precession Fisp Techniques For High Field Preclinical Magnetic Resonance Imaging written by Ying Gao (Gao) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Biology categories.
Preclinical magnetic resonance imaging (MRI) is critical in the investigation of pathophysiology and therapies. High-field (>= 4.7 T) preclinical MRI scanners have been developed to quantitatively evaluate disease status and the efficacy of novel therapies in a wide variety of rodent models with rigorous validation. High magnetic fields provide increased signal-to-noise ratio (SNR) that can be "traded" for spatial / temporal resolution which is extremely valuable in preclinical imaging. However, high-field preclinical MRI systems also face challenges that affect imaging quality, in which B0 inhomogenieties are a major source of artifacts and entail difficulties of conventional clinical acquisitions in low-field settings applied at high fields. In this work, three MRI techniques were developed for high-field preclinical MRI scanners exploiting a fast imaging with steady-state free precession (FISP) acquisition scheme as a technical core to circumvent the significant off-resonance artifacts on high field MRI scanners. First, a FISP-based Look-Locker T1 measurement was developed as a non-invasive and sensitive imaging marker to quantitatively assess autosomal recessive polycystic kidney disease (ARPKD) liver disease in the PCK rat model of ARPKD. Second, a rapid and quantitative arterial spin labeling (ASL)-FISP technique was developed for high-field preclinical MRI scanners to provide perfusion-weighted images in less than 2 s with minimal image artifacts and further investigated in neuroimaging. Third, an initial preclinical 7 T MRI implementation of the highly novel magnetic resonance fingerprinting (MRF) methodology was developed and in vivo preclinical MRF results in mouse kidneys and brain tumor models demonstrated an inherent resistance to respiratory motion artifacts as well as sensitivity to known pathology. Overall, FISP-based quantitative MRI techniques developed here will create a wealth of opportunities for preclinical imaging applications and inform future clinical imaging studies.
Ultrahigh Field Magnetic Resonance Imaging
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Author : Judy Alper
language : en
Publisher:
Release Date : 2016
Ultrahigh Field Magnetic Resonance Imaging written by Judy Alper and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Magnetic resonance imaging (MRI) may be used to provide detailed images of the human body with excellent soft tissue contrast. Alongside its current widespread clinical applications for diagnosis and treatment, MRI allows researchers to measure structure and function of different tissue types in order to advance our understanding of human biology and enable new medical applications of MRI. In particular, diseases affecting nerves and vessels, such as trigeminal neuralgia, with uncertain etiology can be studied using multiple MRI modalities so that treatment planning can we more effective and patient outcomes can be improved. Ultrahigh field MRI scanners, such as those operating at 7-‐tesla (7T), provide increased signal-‐to-‐noise ratio, which can be translated to higher spatial resolution. Additional advantages of high magnetic field MRI include enhanced vascular contrast as well as improved spectral separation and quantification for MR spectroscopy. These benefits over MRI at lower field strengths make ultrahigh field MRI a powerful new tool for performing quantitative image analysis with increased accuracy. One quantitative application of MRI is the detection and visualization of cells labeled with magnetic nanoparticles. This unconventional use of the imaging modality enables very effective imaging of cells or lesions tagged with these particles. The projects explored herein consist of such quantitative image analysis using advanced imaging techniques, including ultrahigh field MRI.
Biomedical Index To Phs Supported Research
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Author :
language : en
Publisher:
Release Date : 1995
Biomedical Index To Phs Supported Research written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Medicine categories.
Modular Scalable Techniques For Advanced Magnetic Resonance Systems And Radio Frequency Instrumentation
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Author : Pascal Pawel Stang
language : en
Publisher:
Release Date : 2012
Modular Scalable Techniques For Advanced Magnetic Resonance Systems And Radio Frequency Instrumentation written by Pascal Pawel Stang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Magnetic resonance imaging (MRI) is unique among imaging modalities in providing exceptional versatility for examining a wide spectrum of anatomy and physiological functions. Modern MRI systems are moving toward higher magnetic field strengths for increased signal, and depend on rising receiver and transmitter channel counts to enhance speed, image quality, specificity, and safety. This has left researchers in a predicament. Commercial MRI scanners are becoming ever more capable and complex, yet by their nature inevitably lag the leading edge of science, failing to anticipate new research directions. Moreover, their closed proprietary hardware, software, and interfaces frustrate any expansion or adaptation to new techniques and experiments. Developed to address these challenges, the Medusa MRI console is a modular scalable open platform for advanced MRI research and development. Medusa enables MR methods and applications that would have been challenging or impossible using only commercial hardware, and does so with an efficient flexible architecture designed to grow to meet future needs. The Medusa MRI console delivers the complete set of functionality required for MRI including multi-channel radio-frequency (RF) excitation and reception, gradient waveform generation, coil and amplifier gating, and an open software platform for pulse sequencing and experimental development. Key features of Medusa include the use of direct-conversion digital RF components, distributed processing and memory for modularity and flexibility, and USB 2.0 High-Speed (480Mb/s) interfaces to the host PC. Medusa was first tested with the novel Stanford University Pre-Polarized MRI scanner, and is now used regularly for experiments on a diverse range of commercial and custom-built imaging systems. A significant application of Medusa has been the investigation and development of MRI Parallel Transmit techniques (PTx), which hold promise for improving MR safety and high-field image quality. Yet PTx methods demand high-fidelity delivery of RF pulses at kilowatt power levels across multiple channels into an unknown load. Vector Iterative Predistortion (VIP) was developed to address this challenge, using Medusa to encode the non-ideal response from RF amplifiers using sensors and iteratively pre-distort the input to achieve desired output. Even when used with cost-efficient low-fidelity RF power amps, VIP drives errors to below 0.1~dB and +/-1~degree phase, and is capable of correcting time-dynamic memory effects where traditional look-up table methods fail. Accurate RF sensing is essential in any RF control system, and on-coil and in-line vector RF sensing approaches were developed to enable real-time current, power, and impedance measurements. Notably, this monitoring permits not only the hardware characterization and control needed for VIP, but can also detect patient motion, cardiac and respiratory rhythms, and has the potential to assess and improve MR safety for patients with implanted devices.