1. From the Department of Bioengineering (E.B., A.H., F.C.), Department of Radiology (K.H., L.H., S.K., A.H., F.C.), Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine (N.K., A.M.), and Department of Surgery (M.M.), University of California San Diego, 9500 Gilman Dr, MC 0412, La Jolla, CA 92093.