1 Diagnostic and Interventional Ultrasound Unit, Valle del Serchio General Hospital, Lucca, Italy.
2 Emergency Medicine Unit, San Giovanni di Dio Hospital, Florence, Italy.
3 Pulmonary Medicine Unit, Department of Medical and Surgical Sciences, Fondazione Policlinico Universitario Agostino Gemelli, Istituto di Ricovero e Cura a Carattere Scientifico, Rome, Italy.
4 Department of Information Engineering and Computer Science, Ultrasound Laboratory Trento, University of Trento, Trento, Italy.