1. From the Department of Radiology (A.S.O., S.H., D.A.L.), Department of Biostatistics (M.S., K.P.), Division of Rheumatology, Department of Medicine (E.A.R.), and Division of Pulmonary and Critical Care Medicine, Department of Medicine (J.D.C.), National Jewish Health, 1400 Jackson St, Room A367, Denver, CO 80206.