1. Department of Radiology; University of Iowa; Iowa City Iowa USA
2. Department of Internal Medicine; University of Iowa; Iowa City Iowa USA
3. Department of Biomedical Engineering; University of Iowa; Iowa City Iowa USA
4. Department of Radiology; National Jewish Health Center; Denver Colorado USA
5. Division of General Medicine; Division of Pulmonary; Allergy and Critical Care; Department of Medicine; Columbia University Medical Center; New York New York USA
6. Department of Epidemiology; Columbia University Medical Center; New York New York USA
7. Clinical Research Imaging Centre, Queen's Medical Research Institute, University of Edinburgh; Scotland UK
8. Robarts Research Institute, University of Western Ontario; London Canada
9. Department of Medical Biophysics; University of Western Ontario; London Canada