This work would not have been possible without the financial support of the Vanderbilt Physician Scientist Development Award, the American Roentgen Ray Society Scholarship or the Vanderbilt University Medical Center Department of Radiology and Radiological Sciences. I am especially indebted to Dr. Martin Sandler, Chairman of the Department of Radiology, and Dr. John Worrell, Chief of the Section of Thoracic Radiology, who have been supportive of my career goals and who worked actively to provide me with the protected academic time to pursue those goals. I am grateful to all of those with whom I have had the pleasure to work during this and other related projects. Each of the members of my Dissertation Committee has provided me extensive personal and professional guidance and taught me a great deal about both scientific research and life in general. I would especially like to thank Dr. Ron Price, the chairman of my committee. As my teacher and mentor, he has taught me more than I could ever give him credit for here. He has shown me, by his example, what a good scientist (and person) should be. Nobody has been more important to me in the pursuit of this project than the members of my family. I would like to thank my parents, whose love and guidance are with me in whatever I pursue. They are the ultimate role models. Most importantly, I wish to thank my loving and supportive wife, Jennifer, and my three wonderful children, Lauren, Jacob and Elizabeth, who provide unending inspiratio