Author: Youbing Yin Publisher: ISBN: Category : Image registration Languages : en Pages : 140
Book Description
Computational fluid dynamics (CFD) has become an attractive tool in understanding the characteristic of air flow in the human lungs. Inter-subject variations make subject-specific simulations essential for understanding structure-function relationship, assessing lung function and improving drug delivery. However, currently the subject-specific CFD analysis remains challenging due, in large part to, two issues: construction of realistic deforming airway geometry and imposition of physiological boundary conditions. To address these two issues, we develop subject-specific, dynamic lung models by utilizing two or multiple volume multi-detector row computed tomography (MDCT) data sets and image registrations in this thesis. A mass-preserving nonrigid image registration algorithm is first proposed to match a pair of three-dimensional (3D) MDCT data sets with large deformations. A novel similarity criterion, the sum of squared tissue volume difference (SSTVD), is introduced to account for changes in intensity with lung inflation. We then demonstrate the ability to develop dynamic lung models by using a pair of lung volumes to account for deformations of airway geometries and subject-specific boundary conditions. The deformation of the airway geometry is derived by the registration-derived deformation field and subject-specific boundary condition is estimated from regional ventilation in a 3D and one-dimensional (1D) coupled multi-scale framework. Improved dynamic lung models are then proposed from three lung volumes by utilizing nonlinear interpolations. The improved lung models account for nonlinear geometry motions and time-varying boundary conditions during breathing. The capability of the proposed dynamic lung model is expected to move the CFD-based interrogation of lung function to the next plateau.
Author: Kai Ding Publisher: ISBN: Category : Lungs Languages : en Pages : 158
Book Description
The main function of the respiratory system is gas exchange. Since many disease or injury conditions can cause biomechanical or material property changes that can alter lung function, there is a great interest in measuring regional lung function and mechanics. In this thesis, we present a technique that uses multiple respiratory-gated CT images of the lung acquired at different levels of inflation with both breath-hold static scans and retrospectively reconstructed 4D dynamic scans, along with non-rigid 3D image registration, to make local estimates of lung tissue function and mechanics. We validate our technique using anatomical landmarks and functional Xe-CT estimated specific ventilation. The major contributions of this thesis include: 1) developing the registration derived regional expansion estimation approach in breath-hold static scans and dynamic 4DCT scans, 2) developing a method to quantify lobar sliding from image registration derived displacement field, 3) developing a method for measurement of radiation-induced pulmonary function change following a course of radiation therapy, 4) developing and validating different ventilation measures in 4DCT. The ability of our technique to estimate regional lung mechanics and function as a surrogate of the Xe-CT ventilation imaging for the entire lung from quickly and easily obtained respiratory-gated images, is a significant contribution to functional lung imaging because of the potential increase in resolution, and large reductions in imaging time, radiation, and contrast agent exposure. Our technique may be useful to detect and follow the progression of lung disease such as COPD, may be useful as a planning tool during RT planning, may be useful for tracking the progression of toxicity to nearby normal tissue during RT, and can be used to evaluate the effectiveness of a treatment post-therapy.
Author: Kaifang Du Publisher: ISBN: Category : Image registration Languages : en Pages : 196
Book Description
Current radiation therapy (RT) planning for limiting lung toxicity is based on a uniform lung function with little consideration to the spatial and temporal pattern of lung function. Establishment of relationships between radiation dose and changes in pulmonary function can help predict and reduce the RT-induced pulmonary toxicity. Baseline measurement uncertainty of pulmonary function across scans needs to be assessed, and there is a great interest to compensate the pulmonary function for respiratory effort variations. Respiratory-gated 4DCT imaging and image registration can be used to estimate the regional lung volume change by a transformation-based ventilation metric which is computed directly from the deformation field, or a intensity-based metric which is based on CT density change in the registered image pair.
Author: Lawrence Joseph LeBlanc Publisher: ISBN: Category : Asthma Languages : en Pages : 91
Book Description
Aerosolized drug delivery to the human lungs for asthma treatment has long been studied and yet the relationship between the delivery efficacy and the inter-subject variability due to gender, age, and disease severity remains unclear. A recent imaging-based cluster analysis on a population of asthmatic patients identifies four clusters with distinct structural and functional characteristics. The use of cluster membership to explore inter-subject variability by investigating numerically the air flow and particle transport in representative subjects of the asthmatic clusters on inhalation drug delivery in asthma sub-populations is proposed. Large-eddy simulations using computed tomography (CT)-based airway models were performed with a slow and deep breathing profile corresponding to application of a metered dose inhaler. Physiologically consistent subject specific boundary conditions in peripheral airways were produced using an image registration technique and a resistance network compliance model. Particle simulations and final deposition statistics were calculated for particle sizes ranging from 1-8 μm. The results suggested an emphasis on the importance of airway constriction for regional particle deposition and prominent effects of local features in lobar, segmental, and sub-segmental airways on overall deposition patterns. Asthmatic clusters characterized by airway constriction had an increase in deposition efficiency in lobar, segmental, and sub-segmental airways. Local constrictions produced jet flows that impinged on distal bifurcations and resulted in large inertial depositions. Decreased right main bronchus (RMB) branching angle decreased the fraction of particles ventilated to the right upper lobe (RUL). Cluster-based computational fluid dynamics results demonstrate particle deposition characteristics associated with imaging based variables that could be useful for future drug delivery improvements.
Author: Nariman Jahani Publisher: ISBN: Category : Asthmatics Languages : en Pages : 109
Book Description
In addition, 4D-CT data sets for six mild/moderate asthmatic subjects are added during tidal breathing following acquisition of two static scans at TLC and FRC. We analyze those data to assess ventilation heterogeneity, non-linear deformation and hysteresis of lung motion to distinguish regional and global features of asthmatic lungs from those of healthy lungs during breathing. Eventually, 4D-CT data for healthy and asthmatic lungs are utilized to derive physiologically consistent boundary conditions for computational fluid dynamic (CFD) simulation of airflow in the human lungs during tidal breathing. We investigate the effect of dynamic breathing on air flow distribution and pressure drop along the central airways.
Author: William J. Mullally Publisher: ISBN: Category : Languages : en Pages : 180
Book Description
Abstract: This thesis arises out of the study of lung physiology and the development of new techniques to help analyze the complex and prodigious amount data which modem medical imaging can provide. This document describes work in two major directions. The first is an investigation into which airways in the human airway tree contribute to the decrease in lung function in asthmatics. This works pulls together a number of well understood methods in image analysis and image registration with image data on ventilation defects and methods for building computation models of the human airway tree. We show how to incorporate ventilation defects observed in image data into subject specific models of the human airway tree. Our study indicates that ventilation defects may be caused by closures of larger airways than previously reported. Our second effort has been to advance the field of image registration to solve image alignment problems presented in the study of acute respiratory distress syndrome (ARDS). This has led us to develop two novel image registration techniques: an approach for cost-switching in non-rigid image registration and an approach to image registration using classifiers learned from example images. Our cost-switching approach has led to the first accurate semi-automatic non-rigid registration of images of healthy lungs to those of lungs after the onset of ARDS. Our example-based approach uses multiple classifiers to achieve rigid registration when image appearance has changed dramatically and non-uniformly. We show a significant increase in registration accuracy in comparison to an approach using mutual information.
Author: Jiyuan Tu Publisher: Springer Science & Business Media ISBN: 9400744870 Category : Technology & Engineering Languages : en Pages : 383
Book Description
Traditional research methodologies in the human respiratory system have always been challenging due to their invasive nature. Recent advances in medical imaging and computational fluid dynamics (CFD) have accelerated this research. This book compiles and details recent advances in the modelling of the respiratory system for researchers, engineers, scientists, and health practitioners. It breaks down the complexities of this field and provides both students and scientists with an introduction and starting point to the physiology of the respiratory system, fluid dynamics and advanced CFD modeling tools. In addition to a brief introduction to the physics of the respiratory system and an overview of computational methods, the book contains best-practice guidelines for establishing high-quality computational models and simulations. Inspiration for new simulations can be gained through innovative case studies as well as hands-on practice using pre-made computational code. Last but not least, students and researchers are presented the latest biomedical research activities, and the computational visualizations will enhance their understanding of physiological functions of the respiratory system.
Author: Alexander Schmidt-Richberg Publisher: Springer Science & Business Media ISBN: 3658016620 Category : Computers Languages : en Pages : 179
Book Description
Various applications in the field of pulmonary image analysis require a registration of CT images of the lung. For example, a registration-based estimation of the breathing motion is employed to increase the accuracy of dose distribution in radiotherapy. Alexander Schmidt-Richberg develops methods to explicitly model morphological and physiological knowledge about respiration in algorithms for the registration of thoracic CT images. The author focusses on two lung-specific issues: on the one hand, the alignment of the interlobular fissures and on the other hand, the estimation of sliding motion at the lung boundaries. He shows that by explicitly considering these aspects based on a segmentation of the respective structure, registration accuracy can be significantly improved.
Author: Sandeep Bodduluri Publisher: ISBN: Category : Lungs Languages : en Pages : 143
Book Description
Chronic obstructive pulmonary disease (COPD) is a growing health concern associated with high morbidity and mortality, and is currently the third-ranked cause of death in the United States. COPD is characterized by airflow limitation that is not fully reversible and includes chronic bronchitis, functional small airway disease, and emphysema. The interrelationship between emphysema and airway disease in COPD makes it a highly complex and heterogeneous disorder. Appropriate diagnosis of COPD is vital to administer targeted therapy strategies that can improve patient's quality of life and reduce the frequency of COPD associated exacerbations. Although spirometry or pulmonary function tests are currently the gold standard for the diagnosis and staging of the disease, their lack of reproducibility and minimal information on regional characterization of the lung tissue destruction makes it hard to rely on to phenotype COPD population and predict disease progression. Quantification of COPD, as done by computed tomography (CT) methods has seen significant advancements, helping us understand the complex pathophysiology of this disease. The prospective and established techniques that are derived from CT imaging such as densitometry, texture, airway, and pulmonary vasculature-based analyses have been successful in regional characterization of emphysema related lung tissue destruction and airway disease related morphological changes in COPD patients. Although, these measures enriched our diagnostic and treating capability of COPD, they lack information on patient specific alterations in lung mechanics and regional parenchymal stresses. This valuable information can be achieved through the use of image registration protocols. Our main goal of this research work is to examine and evaluate the role of lung mechanical measures derived from CT image registration techniques in COPD diagnosis, phenotyping, and progression.
Author: Joseph M. Reinhardt Publisher: Frontiers Media SA ISBN: 2832547974 Category : Science Languages : en Pages : 143
Book Description
Imaging techniques have been used for decades to detect anomalies, study organ function and for diagnostic purposes. Advances in imaging techniques and image processing as well as a wider availability of lung imaging is providing an increasing amount of data and new insights into lung structure and function and their alterations in common lung diseases. Functional imaging biomarkers have the potential to better characterize individual patient phenotypes, predict disease trajectories, and help personalize therapy. The wealth of new data also confronts us with new challenges in terms of identifying, quantifying, deciphering, and standardizing image-based parameters pertaining to regional lung function.
Author: Youbing Yin
Author: Kai Ding
Author: Kaifang Du
Author: Lawrence Joseph LeBlanc
Author: Nariman Jahani
Author: William J. Mullally
Author: Jiyuan Tu
Author: Alexander Schmidt-Richberg
Author: Sandeep Bodduluri
Author: Joseph M. Reinhardt