1. From the Section of Respiratory Medicine, Department of Experimental and Clinical Medicine, University of Florence, Careggi University Hospital, Largo A. Brambilla 3, 50134 Florence, Italy (M.O., M. Paoletti, F.B., G.C., M. Pistolesi); and Departments of Pulmonology (R.I.) and Radiological Sciences (A.R.L.), Gemelli University Hospital, Catholic University of the Sacred Heart, Rome, Italy.