Functional Lung Imaging PDF

Preface

In recent years, the field of medical imaging has rapidly expanded from the morphological into the functional domain. This is due in part to the veritable explosion in raw computing power and to significant advances in imaging hardware. The computer revolution and the development of powerful post-processing techniques have helped to crate a new and emerging medical domain, that of functional imaging.

Functional imaging is a novel field that provides real-time information about anatomic structure and performance of the human body. It is a multidisciplinary field that combines the expertise of radiology, bioengineering, physics, medicine, and surgery. The field is becoming established in the realm of radiology and the neurosciences (where it was first developed), but is unfamiliar territory to the vast majority of clinicians and researchers interested in pulmonary structure and function.

The goal of this volume is to describe the state of the art in the field of functional pulmonary imaging. International leaders in the fields of computed tomography, magnetic resonance, and nuclear medicine will describe advances in lung imaging. Together with respiratory physicians, these authors will translate and apply potential clinical applications of this new technology to various disease states. It is expected that this book will have a very wide audience. Radiologists, chest physicians, physiologists, respiratory therapists, and researchers interested in disease of the chest are but a few of the potential readers. This volume will have an international scope and list of contributors.

Currently, most information about lung function is derived from the use of a battery of pulmonary function tests. Pulmonary function testing presents global information about lung dysfunction, but cannot impart information about anatomic localization of the abnormal lung. Until recently, lung imaging provided only static anatomic information, but functional imaging using computed tomography can yield information about gas distribution, ventilation, vasculature, and ventilation/perfusion ( V/Q ) relationships. It can quantify and reveal the anatomic distribution of emphysema in the lung as well as provide information about airway size and respiratory mechanics.

Functional lung imaging has also expanded into the field of magnetic resonance with novel sequences in the field of proton magnetic resonance imaging and with the introduction of hyperpolarized noble gas imaging, such as ³He imaging. ³He is a biologically inert, non-radioactive, poorly absorbed gas that is used as a dynamic inhaled contrast agent to provide exquisite images of lung airspaces. When inhaled, dynamic cine images can be created and displayed which demonstrate helium ventilation in the lung. ³He images can be processed mathematically to map the distribution of inhaled gas, the dimensions of distal airspaces, and even the partial pressure of oxygen in the airspaces. Further processes of signal intensity produce three-dimensional images of pulmonary V/Q ratios. Topical heterogeneity of V/Q matching may be a particularly sensitive indicator of early lung dysfunction. Clinically, it may be useful in the early detection of obliterative bronchiolitis following lung transplantation, and in the early detection of emphysema. Functional imaging may be particularly useful in guiding surgeons performing lung volume reduction surgery to target areas of diseased lung.

In the field of nuclear medicine, there have been great strides in metabolic imaging using 18F-fluorodeoxyglucose positron emission tomography (FDGPET) and single proton emission-computed tomography (SPECT). FDG-PET has been shown useful in differentiating benign and malignant processes, and in imaging the activity of various inflammatory lung diseases. FDG-PET may help clinicians determine when to treat various lung diseases.

This book will describe the physiological basis of functional lung imaging and demonstrate its applicability to the study of lung disease. Functional imaging techniques will provide powerful tools in the medical armamentarium to help understand bodily function in health and disease. The field will improve insight in the diagnosis and treatment of various forms of human pathology.