Download or read book Hyperpolarized Noble Gas Magnetic Resonance Imaging of the Ex Vivo Rodent Lung written by David M. L. Lilburn and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hyperpolarized Noble Gas Magnetic Resonance Imaging of the Ex Vivo Rodent Lung written by D. M. L. Lilburn and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hyperpolarized Noble Gas Magnetic Resonance Imaging and Dynamic Spectroscopy for Investigation of Rat Models of Lung Inflammation written by Matthew Stephen Fox and published by . This book was released on 2012 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Imaging of the lungs using non-ionizing approaches such as hyperpolarized 3He and 129Xe magnetic resonance imaging (MRI) is a useful tool both for research and clinical applications. This work focused on development of 129Xe MRI techniques to investigate inflammation in rat lungs. A rodent model of inflammation, specifically radiationinduced lung injury (RILI) was developed using a collimated 60Co source. A quantitative MRI technique measuring absolute ventilated lung volume (values obtained from rats using the previously established 3He method and those obtained with 129Xe, the usefulness of 129Xe for future investigations of.
Download or read book Hyperpolarized Noble Gas MRI of Human Lungs in 150G Magnetic Field written by Adelaide Zhang and published by . This book was released on 2000 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book MRI of the Lung written by Hans-Ulrich Kauczor and published by Springer Science & Business Media. This book was released on 2008-10-28 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Diffusion Relaxation and Magnetic Resonance Imaging Studies of Noble Gases written by Ivan Emilov Dimitrov and published by . This book was released on 2000 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxygen enhanced Magnetic Resonance Imaging of Mice Lungs written by Kristina Nancy Watt and published by . This book was released on 2007 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pulmonary magnetic resonance (MR) imaging provides valuable information about lung anatomy and perfusion and ventilation physiology. Oxygen-enhanced MR imaging visualizes the effect of ventilation using inhaled molecular oxygen as a T1-shortening contrast agent. The technique is challenged, however, by low proton density of lung tissue and cardiopulmonary physiology that result in reduced MR signal and increased motion artifacts. With the growing interest in mouse models of respiratory disease, application of human pulmonary MR techniques to mice is highly desirable. The purpose of this work was to develop oxygen-enhanced MR imaging as a non-invasive tool to examine ventilation in free-breathing mice. An optimized cardiac-triggered, respiratory-gated fast spin echo sequence was developed for oxygen-enhanced MR and successfully demonstrated in normal mice. Ventilation was visualized as significant signal enhancement in the lung parenchyma with pure oxygen inhalation. This sequence shows potential for application to studies of abnormal ventilation in models of pulmonary disease.
Download or read book A Pseudo Non Cartesian Pulse Sequence For Hyperpolarized Xenon 129 Gas MRI of Rodent Lungs At Low Magnetic Field Strength written by Krzysztof Wawryzn and published by . This book was released on 2014 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: Background: Early diagnosis of radiation-induced lung injury (RILI) following radiation therapy is critical for prevention of permanent lung damage. Pulmonary imaging using magnetic resonance imaging (MRI) of the apparent diffusion coefficient (ADC) of hyperpolarized xenon (129Xe) gas shows promise for early measurement of RILI. Methods: An ultra-short echo time imaging sequence based on a pseudo-Cartesian kspace trajectory, known as Sectoral, is implemented at low magnetic field (0.07 T) for efficient use of the non-renewable magnetization of hyperpolarized 129Xe gas. A pilot study was performed to demonstrate the feasibility of ADC mapping using the Sectoral sequence on healthy and 2-weeks post irradiated rats. Results: A significant (p
Download or read book Optimization of Hyperpolarized Noble Gas Magnetic Resonance Imaging written by Lei Zhao and published by . This book was released on 2000 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lung Magnetic Resonance Imaging as a Non invasive Alternative to Assess Experimental Pulmonary Diseases in Small Rodents written by François-Xavier Blé and published by . This book was released on 2007 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic resonance imaging (MRI) is able to detect water content in the biological tissue and thus to non-invasively assess on a regional basis infiltrated water and/or secreted fluids and/or tissue densification. In pulmonary diseases such as asthma, chronic obstructive pulmonary diseases or fibrosis, plasma exudation, mucus secretion and thickening of the lung tissue constitute hallmarks of the pathological status that directly contribute to functional impairment. These features are well conserved in experimental pulmonary disease models in the small rodents. A particular interest is given to murine models that have provided, in parallel to the technological progress in genetic engineering and molecular biology, a reliable in vivo support for lung disease understanding and investigation. Nowadays, routine methods used to evaluate disease state of the lung in these models are either terminal or gives functional estimation of the global airways.Therefore, we have set up a method using MRI technique to non-invasively depict different hallmarks occurring in a murine model of asthma. In this thesis, we have demonstrated that proton MRI provides a relevant mean to assess and follow signals associated with the plasma leakage and mucus secretions in the lung, which are both important features of the inflammatory response following allergenic provocation. To further confirm these findings, we have also validated in this model the effect of pharmacological tools. We chose to study sphingosine-1-phosphate (S1P) pharmacology on the basis of recent publications indicating a possible implication of this endogenous mediator in inflammation and lung barrier integrity in models of asthma. In two studies examining the effects of the general S1P agonist FTY720 and of the S1P2 antagonist JTE013, the incidence of plasma leakage on fluid signal detection was highlighted in our murine model of airway inflammation and confirmed by histology and BAL fluid analyses. Additionally, since the technique had been previously set up in the rat, we extended the knowledge in this species. In this regard, we achieved the selective detection and monitoring of mucus dynamics by MRI with the use of a specific contrast agent in a model of endotoxin-induced mucus hypersecretion. Besides, we also demonstrated the capabilities of MRI to follow the hydration of airway secretions. In this non-inflammatory model, the formation of MRI fluid signals were induced by hypertonic saline instillation and dose-dependently enhanced by different compounds that interact directly or indirectly with epithelial Na+ channel (ENaC), a major regulator of airway surface liquid hydration. These studies have been successfully performed in the rat with the perspective of future translation to murine models for transgenic application. Finally, we have partially validated the application of this technique to a less acute model, the murine bleomycin-induced fibrosis. This model has been chosen regarding its admitted relevance to mimic global characteristics of human pulmonary fibrosis in addition to its simplicity to be set up. In this study, we have been able to follow by MRI the course of edematous, mucous and/or fibrotic features in correlation with histological findings. In summary, the present work is bringing evidence of possible contributions of MRI in pulmonary disease investigations in mouse and rat, and postulates for its use to complete and/or replace the methods used nowadays to evaluate experimental murine models.
Download or read book Investigation of Neonatal Pulmonary Structure and Function Via Proton and Hyperpolarized Gas Magnetic Resonance Imaging written by Nara Savoye Higano and published by . This book was released on 2017 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic resonance imaging (MRI) is a modality that utilizes the phenomenon of nuclear magnetic resonance (NMR) to yield tomographic images of the body. Proton (1H) MRI has historically been successful in soft tissues but has suffered in the lung due to a variety of technical challenges, such as the low proton-density, rapid T2* relaxation time of the lung parenchymal tissue, and inherent physiological motion in the chest. Recent developments in radial ultrashort echo time (UTE) MRI have in part overcome these issues. In addition, there has been much progress in techniques for hyperpolarization of noble gases (3He and 129Xe) out of thermal equilibrium via spin exchange optical pumping, which can greatly enhance the gas NMR signal such that it is detectable within the airspaces of the lung on MRI.The lung is a unique organ due to its complex structural and functional dynamics, and its early development through the neonatal (newborn) period is not yet well understood in normal or abnormal conditions. Pulmonary morbidities are relatively common in infants and are present in a majority of patients admitted to the neonatal intensive care unit, often stemming from preterm birth and/or congenital defects. Current clinical lung imaging in these patients is typically limited to chest x-ray radiography, which does not provide tomographic information and so has lowered sensitivity. More rarely, x-ray computed tomography (CT) is used but exposes infants to ionizing radiation and typically requires sedation, both of which pose increased risks to pediatric patients. Thus the opportunity is ripe for application of novel pulmonary MRI techniques to the infant population. However, MR imaging of very small pulmonary structure and microstructure requires fundamental changes in the imaging theory of both 1H UTE MRI and hyperpolarized gas diffusion MRI. Furthermore, such young patients are often non-compliant, yielding a need for new and innovative techniques for monitoring respiratory and bulk motion.This dissertation describes methodology development and provides experimental results in both 1H UTE MRI and hyperpolarized 3He and 129Xe gas diffusion MRI, with investigation into the structure and function of infant lungs at both the macrostructural and microstructural level. In particular, anisotropically restricted gas diffusion within infant alveolar microstructure is investigated as a measurement of airspace size and geometry. Additionally, the phenomenon of respiratory and bulk motion-tracking via modulation of the k-space center's magnitude and phase is explored and applied via UTE MRI in various neonatal pulmonary conditions to extract imaging-based metrics of diagnostic value. Further, the proton-density regime of pulmonary UTE MRI is validated in translational applications. These techniques are applied in infants with various pulmonary conditions, including patients diagnosed with bronchopulmonary dysplasia, congenital diaphragmatic hernia, esophageal atresia/tracheoesophageal fistula, tracheomalacia, and no suspected lung disease. In addition, explanted lung specimens from both infants with and without lung disease are examined.Development and implementation of these techniques involves a strong understanding of the physics-based theory of NMR, hyperpolarization, and MR imaging, in addition to foundations in hardware, software, and image analysis techniques. This thesis first outlines the theory and background of NMR, MRI, and pulmonary physiology and development (Part I), then proceeds into the theory, equipment, and imaging experiments for hyperpolarized gas diffusion MRI in infant lung airspaces (Part II), and finally details the theory, data processing methods, and applications of pulmonary UTE MRI in infant patients (Part III). The potential for clinical translation of the neonatal pulmonary MRI methods presented in this dissertation is very high, with the foundations of these techniques firmly rooted in the laws of physics.
Download or read book Magnetic Resonance Imaging Techniques for Rodent Pulmonary Imaging written by Eriko Suzanne Yoshimaru and published by . This book was released on 2013 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic Resonance Imaging (MRI) is a safe and widely used diagnostic imaging method that allows in vivo observation of anatomy and characterization of tissues. MRI provides a method to monitor patients without invasive measures, making it suitable for both diagnostics and longitudinal monitoring of various pathologies. A notable example of this is the work carried out by the Alzheimer's Disease Neuroimaging Initiative (ADNI), which utilizes imaging, including multiple MRI techniques, to monitor disease progression in AD patients and evaluates treatment responses and prevention strategies. Similarly, MRI has been extensively used in evaluating diseases in a variety of animal models. In order to detect subtle anatomical changes over time, small differences in MR images must be accurately extracted. Furthermore, to ensure that the extracted differences are due to anatomical changes rather than equipment variance, it becomes essential to monitor and to assess the MRI system stability. In the first chapter of the dissertation, a method for monitoring pre-clinical MRI system performance is discussed. The technique developed during the study provides a fast and simple method to monitor pre-clinical MRI systems but also has applications for all areas of MRI. The second chapter describes the development of a 3D UTE MRI method for pulmonary imaging in freely breathing mice. The development of the 3D UTE sequence for pulmonary MRI has demonstrated its ability to collect images without noticeable motion artifacts and with appreciable signal from the lung parenchyma. Furthermore, images at two distinct respiratory phases were reconstructed from a single data set, providing functional information of the rodents' lungs. Finally, in the third chapter, 3D 19F UTE MRI is evaluated for imaging in vivo distributions of perfluorocarbon (PFC) nanoemulsions for measuring pulmonary inflammation. Building upon the development of pulmonary imaging, fluorinated contrast agents made from PFCs were used to target immune cells in response to pulmonary pathology. Both 3D 1H and 19F UTE MRI were used to acquire pulmonary images of mouse models documented to have pulmonary pathology. Even though the mice had confirmed elevation in alveolar macrophage counts, no visible 19F signal accumulation within the pulmonary tissue was observed with MRI.
Download or read book Investigation of Lung Structure function Relationships Using Hyperpolarized Noble Gases written by Robert P. Thomen and published by . This book was released on 2016 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic Resonance Imaging (MRI) is an application of the nuclear magnetic resonance (NMR) phenomenon to non-invasively generate 3D tomographic images. MRI is an emerging modality for the lung, but it suffers from low sensitivity due to inherent low tissue density and short T2*. Hyperpolarization is a process by which the nuclear contribution to NMR signal is greatly enhanced to more than 100,000 times that of samples in thermal equilibrium. The noble gases 3He and 129Xe are most often hyperpolarized by transfer of light angular momentum through the electron of a vaporized alkali metal to the noble gas nucleus (called Spin Exchange Optical Pumping). The enhancement in NMR signal is so great that the gas itself can be imaged via MRI, and because noble gases are chemically inert, they can be safely inhaled by a subject, and the gas distribution within the interior of the lung can be imaged. The mechanics of respiration is an elegant physical process by which air is is brought into the distal airspaces of the lungs for oxygen/carbon dioxide gas exchange with blood. Therefore proper description of lung function is intricately related to its physical structure, and the basic mechanical operation of healthy lungs -- from pressure driven airflow, to alveolar airspace gas kinetics, to gas exchange by blood/gas concentration gradients, to elastic contraction of parenchymal tissue -- is a process decidedly governed by the laws of physics. This dissertation will describe experiments investigating the relationship of lung structure and function using hyperpolarized (HP) noble gas MRI. In particular HP gases will be applied to the study of several pulmonary diseases each of which demonstrates unique structure-function abnormalities: asthma, cystic fibrosis, and chronic obstructive pulmonary disease. Successful implementation of an HP gas acquisition protocol for pulmonary studies is an involved and stratified undertaking which requires a solid theoretical foundation in NMR and hyperpolarization theory, construction of dedicated hardware, development of dedicated software, and appropriate image analysis techniques for all acquired data. The author has been actively involved in each of these and has dedicated specific chapters of this dissertation to their description. First, a brief description of lung structure-function investigations and pulmonary imaging will be given (chapter 1). Brief discussions of basic NMR, MRI, and hyperpolarization theory will be given (chapters 2 and 3) followed by their particular methods of implementation in this work (chapters 4 and 5). Analysis of acquired HP gas images will be discussed (chapter 6), and the investigational procedures and results for each lung disease examined will be detailed (chapter 7). Finally, a quick digression on the strengths and limitations of HP gas MRI will be provided (chapter 8).
Download or read book Hyperpolarized Carbon 13 Magnetic Resonance Imaging as a Tool for Assessing Lung Transplantation Outcomes written by Sarmad Siddiqui and published by . This book was released on 2019 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lung transplantation is the established treatment for patients with chronic, end-stage lung diseases such as chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF) and cystic fibrosis (CF). However, its utility remains limited by the chronic shortage of donor lungs, limited lung preservation strategies and post-transplant complications leading to graft failure. Although efforts have been made to expand the limited pool of viable donor lungs via novel preservation strategies such as ex vivo lung perfusion (EVLP), our limited understanding of the mechanism and progression of donor lung injury continues to inhibit our ability to fully exploit these advances to improve lung transplant outcomes. Furthermore, the clinical standard for post-transplant assessment is limited to whole lung measurement such as pulmonary functional tests (PFTs) and structural imaging via radiography or HRCT, both of which lack the necessary sensitivity to detect lung rejection early. Given these limitations of currently available pre- and post-transplant lung assessment tools, a novel metabolic biomarker may provide higher sensitivity for determining the viability of donated lungs, as well as for assessing the onset of rejection before permanent structural changes in the lungs become apparent. We proposed that hyperpolarized (HP) [1-13C]pyruvate magnetic resonance imaging (MRI)--which provides real-time metabolic assessment of tissue based on the conversion of [1-13C] pyruvate to [1-13C]lactate via glycolysis, or to 13C bicarbonate via oxidative phosphorylation--may be an effective tool for assessing the health of donated lungs and may also serve as an early biomarker for detecting pulmonary graft dysfunction (PGD)-associated inflammation or acute lung rejection. In a rat model, we demonstrated the feasibility of using HP [1-13C]pyruvate nuclear magnetic resonance (NMR) spectroscopy to assess the viability of ex vivo perfused lungs. We further showed that our technique can be used to measure the improved viability of those lungs after treatment with ascorbic acid. Finally, translating our previously developed technique to in vivo HP [1-13C]pyruvate imaging of an inflamed rat lung, we not only demonstrated its utility for detecting lung transplantation rejection, but found that the HP lactate-to-pyruvate ratio is a better predictor of acute lung rejection in a rat model than computed tomography.
Download or read book Magnetic Resonance Imaging of Hyperpolarised 129Xe Gas in the Human Lungs written by Xiaojun Xu and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Micro imaging of the Mouse Lung Via MRI written by Wei Wang and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantitative measurement of lung microstructure is of great significance in assessment of pulmonary disease, particularly in the earliest stages. Conventional stereological assessment of ex-vivo fixed tissue specimens under the microscope has a long and successful tradition and is regarded as a gold standard, but the invasive nature limits its applications and the practicality of use in longitudinal studies. The technique for diffusion MRI-based 3He lung morphometry was previously developed and validated for human lungs, and was recently extended to ex-vivo mouse lungs. The technique yields accurate, quantitative information about the microstructure and geometry of acinar airways. In this dissertation, the 3He lung morphometry technique is for the first time successfully implemented for in-vivo studies of mice. It can generate spatially-resolved maps of parameters that reveal the microstructure of mouse lung. Results in healthy mice indicate excellent agreement between in-vivo morphometry via 3He MRI and microscopic morphometry after sacrifice. The implementation and validation of 3He morphometry in healthy mice open up new avenues for application of the technique as a precise, noninvasive, in-vivo biomarker of changes in lung microstructure, within various mouse models of lung disease. We have applied 3He morphometry to the Sendai mouse model of lung disease. Specifically, the Sendai-virus model of chronic obstructive lung disease has demonstrated an innate immune response in mouse airways that exhibits similarities to the chronic airway inflammation in human COPD and asthma, but the effect on distal lung parenchyma had not been investigated. We imaged the time course and regional distribution of mouse lung microstructural changes in vivo after Sendai virus (SeV) infection with 1H and 3He diffusion MRI. 1H MR images detected the SeV-induced pulmonary inflammation in vivo and 3He lung morphometry showed modest increase in alveolar duct radius distal to airway inflammation, particularly in the lung periphery, indicating airspace enlargement after virus infection. Another important application of the imaging technique is the study of lung regeneration in a pneumonectomy (PNX) model. Partial resection of the lung by unilateral PNX is a robust model of compensatory lung growth. It is typically studied by postmortem morphometry in which longitudinal assessment in the same animal cannot be achieved. Here we successfully assess the microstructural changes and quantify the compensatory lung growth in vivo in the PNX mouse model via 1H and hyperpolarized 3He diffusion MRI. Our results show complete restoration in lung volume and total alveolar number with enlargement of alveolar size, which is consistent with prior histological studies conducted in different animals at various time points. This dissertation demonstrates that 3He lung morphometry has good sensitivity in quantifying small microstructural changes in the mouse lung and can be applied to a variety of mouse pulmonary models. Particularly, it has great potential to become a valuable tool in understanding the time course and the mechanism of lung growth in individual animals and may provide insight into post-natal lung growth and lung regeneration.
Download or read book Functional Imaging of the Lungs Using Magnetic Resonance Imaging of Inert Fluorinated Gases written by Marcus Couch and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluorine-19 (19F) magnetic resonance imaging (MRI) of the lungs using inhaled inert fluorinated gases can potentially provide high quality anatomical and functional images of the lungs. This technique is able to visualize the distribution of the inhaled gas, similar to hyperpolarized (HP) helium-3 (3He) and xenon-129 (129Xe) MRI. Inert fluorinated gases have the advantages of being nontoxic, abundant, and inexpensive compared to HP gases. Due to the high gyromagnetic ratio of 19F, there is sufficient thermally polarized signal for imaging, and averaging within a single breath-hold is possible due to short longitudinal relaxation times. Since inert fluorinated gases do not need to be hyperpolarized prior to their use in MRI, this eliminates the need for an expensive polarizer and expensive isotopes. Inert fluorinated gas MRI of the lungs has been studied extensively in animals since the 1980s, and more recently in healthy volunteers and patients with lung diseases. This thesis focused on the development of static breath-hold inert fluorinated gas MR imaging techniques, as well as the development functional imaging biomarkers in humans and animal models of pulmonary disease. Optimized ultrashort echo time (UTE) 19F MR imaging was performed in healthy volunteers, and images from different gas breathing techniques were quantitatively compared. 19F UTE MR imaging was then quantitatively compared to 19F gradient echo imaging in both healthy volunteers and in a resolution phantom. A preliminary comparison to HP 3He MR imaging is also presented, along with preliminary 19F measurements of the apparent diffusion coefficient (ADC) and iv gravitational gradients of ventilation in healthy volunteers. The potential of inert fluorinated gas MRI in detecting pulmonary diseases was further explored by performing ventilation mapping in animal models of inflammation and fibrosis. Overall, interest in pulmonary 19F MRI of inert fluorinated gases is increasing, and numerous sites around the world are now interested in developing this technique. This work may help to demonstrate that inert fluorinated gas MRI has the potential to be a viable clinical imaging modality that can provide useful information for the diagnosis and management of chronic respiratory diseases.
