1. Department of Internal Medicine Fondazione Istituto di Ricovero e Cura a Carattere Scientifico, Policlinico San Matteo, University of Pavia Pavia Italy
2. Diagnostic and Interventional Ultrasound Unit Valle del Serchio General Hospital Lucca Italy
3. Pulmonary Medicine Unit, Department of Medical and Surgical Sciences Fondazione Serhii Istituto di Ricovero e Cura a Carattere Scientifico, Policlinico Universitario Agostino Gemelli Rome Italy
4. Department of Information Engineering and Computer Science, Ultrasound Laboratory Trento University of Trento Trento Italy
5. Emergency Medicine Unit General Hospital Voghera Voghera Italy
6. Pulmonary Medicine Unit Codogno Hospital, Azienda Socio Sanitaria Territoriale Lodi Codogno Italy
7. Service of Clinical Epidemiology and Biostatistics Fondazione Istituto di Ricovero e Cura a Carattere Scientifico, Policlinico San Matteo, University of Pavia Pavia Italy