Author: A°smund Kjørstad
Publisher:
ISBN:
Category :
Languages : en
Pages : 109

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Author: Hans-Ulrich Kauczor
Publisher: Springer Science & Business Media
ISBN: 3540346198
Category : Medical
Languages : en
Pages : 315

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During the past decade significant developments have been achieved in the field of magnetic resonance imaging (MRI), enabling MRI to enter the clinical arena of chest imaging. Standard protocols can now be implemented on up-to-date scanners, allowing MRI to be used as a first-line imaging modality for various lung diseases, including cystic fibrosis, pulmonary hypertension and even lung cancer. The diagnostic benefits stem from the ability of MRI to visualize changes in lung structure while simultaneously imaging different aspects of lung function, such as perfusion, respiratory motion, ventilation and gas exchange. On this basis, novel quantitative surrogates for lung function can be obtained. This book provides a comprehensive overview of how to use MRI for imaging of lung disease. Special emphasis is placed on benign diseases requiring regular monitoring, given that it is patients with these diseases who derive the greatest benefit from the avoidance of ionizing radiation.

Author: Susan R. Hopkins
Publisher: Springer
ISBN: 1493974416
Category : Medical
Languages : en
Pages : 338

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The Multiple Inert Gas Elimination Technique (MIGET) is a complex methodology involving specialized gas chromatography and sophisticated mathematics developed in the early 1970’s. Essentially, nobody possesses knowledge of all its elements except for its original developers, and while some practical and theoretical aspects have been published over the years, none have included the level of detail that would be necessary for a potential user to adopt and understand the technique easily. This book is unique in providing a highly detailed, comprehensive technical description of the theory and practice underlying the MIGET to help potential users set up the method and solve problems they may encounter. But it is much more than a reference manual – it is a substantial physiological and mathematical treatise in its own right. It also has a wide applicability – there is extensive discussion of the common biological problem of quantitative inference. The authors took measured whole-lung gas exchange variables, and used mathematical procedures to infer the distribution of ventilation and blood flow from this data. In so doing, they developed novel approaches to answer the question: What are the limits to what can be concluded when inferring the inner workings from the “black box” behavior of a system? The book details the approaches developed, which can be generalized to other similar distributed functions within tissues and organs. They involve engineering approaches such as linear and quadratic programming, and uniquely use mathematical tools with biological constraints to obtain as much information as possible about a “black box” system. Lastly, the book summarizes the hundreds of research papers published by a number of groups over the decades in a way never before attempted in order to marshal the world’s literature on the topic and to provide in one place the wealth of important discoveries, both physiological a nd clinical, enabled by the technique.

Author: Grzegorz Leszek Bauman
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: Grzegorz Leszek Bauman
Publisher:
ISBN:
Category :
Languages : en
Pages : 154

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Author: Katherine Josephine Carey
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Magnetic Resonance Imaging (MRI) is an attractive modality for imaging the pulmonary system at relatively high resolution, especially for longitudinal disease assessment. HP gas MRI provides a means of visualizing pulmonary gas distribution directly, using either HP 3He or HP 129Xe. By using specialized equipment to excite the gases into hyperpolarized states, the net magnetic moment of the gas is temporarily increased, enabling ventilation imaging over a 12-20 second breath-hold. Visualization and quantification of inhaled gas allows for direct functional information while imaging lung structure with conventional MRI in the same study. Functional metrics derived from ventilation patterns, such as the ventilation defect percent (VDP) have been previously established as markers of disease instability in obstructive lung diseases. In this work, we first apply HP gas MRI in asthma to assess regional structure-function relationships with other quantitative imaging modalities. Then we assess VDP as a biomarker in two longitudinal studies, one during a period of disease instability, where we show that VDP is a biomarker of persistent obstructive change reflecting disease progression and provide evidence for VDP as a longitudinal biomarker of asthma instability. We then extend HP gas MRI to study restrictive lung disease in Idiopathic Pulmonary Fibrosis (IPF), first establishing areas of high ventilation as a biomarker of disease stability and providing evidence that ventilation provides information about disease stability following treatment. Finally, we present a case study establishing the feasibility of using HP gas MRI as a longitudinal marker of response to radiation therapy. Overall, this dissertation presents original work establishing VDP as a biomarker of airway obstruction and a longitudinal marker of disease stability in asthma that can benefit drug development by enriching populations with unstable disease and monitoring therapy response. Moreover, this work establishes an initial understanding of ventilation biomarkers in restrictive lung diseases, an area little studied heretofore. Using these results and techniques for further validation of imaging-based asthma phenotypes and the development of ventilation biomarkers in other pulmonary disorders has the potential to improve drug development and support clinical therapy management by better targeting treatment and monitoring their disease stability and progression.

Author: Mitchell S. Albert
Publisher: Academic Press
ISBN: 0128037040
Category : Science
Languages : en
Pages : 334

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Hyperpolarized and Inert Gas MRI: Theory and Applications in Research and Medicine is the first comprehensive volume published on HP gas MRI. Since the 1990’s, when HP gas MRI was invented by Dr. Albert and his colleagues, the HP gas MRI field has grown dramatically. The technique has proven to be a useful tool for diagnosis, disease staging, and therapy evaluation for obstructive lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis. HP gas MRI has also been developed for functional imaging of the brain and is presently being developed for molecular imaging, including molecules associated with lung cancer, breast cancer, and Alzheimer’s disease. Taking into account the ongoing growth of this field and the potential for future clinical applications, the book pulls together the most relevant and cutting-edge research available in HP gas MRI into one resource. Presents the most comprehensive, relevant, and accurate information on HP gas MRI Co-edited by the co-inventor of HP gas MRI, Dr. Albert, with chapter authors who are the leading experts in their respective sub-disciplines Serves as a foundation of understanding of HP gas MRI for researchers and clinicians involved in research, technology development, and clinical use with HP gas MRI Covers all hyperpolarized gases, including helium, the gas with which the majority of HP gas MRI has been conducted

Author: Jinbang Guo
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 155

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Although x-ray computed tomography (CT) is a gold standard for pulmonary imaging, it has high ionizing radiation, which puts patients at greater risk of cancer, particularly in a longitudinal study with cumulative doses. Magnetic resonance imaging (MRI) doesn't involve exposure to ionizing radiation and is especially useful for visualizing soft tissues and organs such as ligaments, cartilage, brain, and heart. Many efforts have been made to apply MRI to study lung function and structure of both humans and animals. However, lung is a unique organ and is very different from other solid organs like the heart and brain due to its complex air-tissue interleaved structure. The magnetic susceptibility differences at the air-tissue interfaces result in very short T2* (~1 ms) of lung parenchyma, which is even shorter in small-animal MRI (often at higher field) than in human MRI. Both low proton density and short T2* of lung parenchyma are challenges for pulmonary imaging via MRI because they lead to low signal-to-noise ratio (SNR) in images with traditional Cartesian methods that necessitate longer echo times ({u2265} 1 ms). This dissertation reports the work of optimizing pulmonary MRI techniques by minimizing the negative effects of low proton density and short T2* of murine lung parenchyma, and the application of these techniques to imaging murine lung. Specifically, echo time (TE) in the Cartesian sequence is minimized, by simultaneous slice select rephasing, phase encoding and read dephasing gradients, in addition to partial Fourier imaging, to reduce signal loss due to T2* relaxation. Radial imaging techniques, often called ultra-short echo-time MRI or UTE MRI, with much shorter time between excitation and data acquisition, were also developed and optimized for pulmonary imaging. Offline reconstruction for UTE data was developed on a Linux system to regrid the non-Cartesian (radial in this dissertation) k-space data for fast Fourier transform. Slab-selected UTE was created to fit the field-of-view (FOV) to the imaged lung without fold-in aliasing, which increases TE slightly compared to non-slab-selected UTE. To further reduce TE as well as fit the FOV to the lung without aliasing, UTE with ellipsoidal k-space coverage was developed, which increases resolution and decreases acquisition time. Taking into account T2* effects, point spread function (PSF) analysis was performed to determine the optimal acquisition time for maximal single-voxel SNR. Retrospective self-gating UTE was developed to avoid the use of a ventilator (which may cause lung injury) and to avoid possible prospective gating errors caused by abrupt body motion. Cartesian gradient-recalled-echo imaging (GRE) was first applied to monitor acute cellular rejection in lung transplantation. By repeated imaging in the same animals, both parenchymal signal and lung compliance were measured and were able to detect rejection in the allograft lung. GRE was also used to monitor chronic cellular rejection in a transgenic mouse model after lung transplantation. In addition to parenchymal signal and lung compliance, the percentage of high-density lung parenchyma was defined and measured to detect chronic rejection. This represents one of the first times quantitative pulmonary MRI has been performed. For 3D radial UTE MRI, 2D golden means (1) were used to determine the direction of radial spokes in k-space, resulting in pseudo-random angular sampling of spherical k-space coverage. Ellipsoidal k-space coverage was generated by expanding spherical coverage to create an ellipsoid in k-space. UTE MRI with ellipsoidal k-space coverage was performed to image healthy mice and phantoms, showing reduced FOV and enhanced in-plane resolution compared to regular UTE. With this modified UTE, T2* of lung parenchyma was measured by an interleaved multi-TE strategy, and T1 of lung parenchyma was measured by a limited flip angle method (2). Retrospective self-gating UTE with ellipsoidal k-space coverage was utilized to monitor the progression of pulmonary fibrosis in a transforming growth factor (TGF)-[alpha] transgenic mouse model and compared with histology and pulmonary mechanics. Lung fibrosis progression was not only visualized by MRI images, but also quantified and tracked by the MRI-derived lung function parameters like mean lung parenchyma signal, high-density lung volume percentage, and tidal volume. MRI-derived lung function parameters were strongly correlated with the findings of pulmonary mechanics and histology in measuring fibrotic burden. This dissertation demonstrates new techniques and optimizations in GRE and UTE MRI that are employed to minimize TE and image murine lungs to assess lung function and structure and monitor the time course of lung diseases. Importantly, the ability to longitudinally image individual animals by these MRI techniques minimizes the number of animals required in preclinical studies and increases the statistical power of future experiments as each animal can serve at its own control.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Pulmonary perfusion is the process of arterial blood flow through the capillary system of the lungs. Pulmonary perfusion is altered in different lung diseases and during various stages of lung disease making it a potential imaging biomarker for disease diagnosis, progression, and response to therapy. Magnetic resonance imaging (MRI) has shown promise as a cross-sectional modality capable of imaging both lung function (perfusion) and structure without ionizing radiation. Dynamic contrast-enhanced MRI, also known as "first pass" or "bolus tracking" is commonly implemented to qualitatively visualize perfusion; furthermore by taking advantage of the temporal behavior quantifying perfusion can be accomplished. However, several challenges exist with current scanning protocols and post-processing methods to quantify pulmonary perfusion. This research aimed to optimize the dose injection protocol, scan parameters, and post-processing steps for pulmonary perfusion. Validation of this research presented was accomplished using positron emission tomography (PET) as the clinical reference in an animal model. Additionally, lung structure is typically desired to complement perfusion for complete lung diagnosis but currently MRI protocols involve two separate scans each optimized for lung perfusion and structure. The feasibility of implementing a 3D radial acquisition for simultaneous acquisition of both lung perfusion and structure is demonstrated in an animal model as well. The purpose of this thesis was to develop tools needed to quantify pulmonary perfusion such that it could be used to monitor progressive lung diseases.

Author: Asvina Jivan
Publisher:
ISBN:
Category :
Languages : en
Pages :

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