Gino Soldati1, Marcello Demi2, Libertario Demi3. 1. Diagnostic and Interventional Ultrasound Unit, Valle del Serchio General Hospital, Lucca, Italy. 2. Department. of Medical Image Processing, Fondazione Toscana Gabriele Monasterio, Pisa, Italy. 3. Department of Information Engineering and Computer Science, University of Trento, Trento, Italy.