Letter to the Editor on the Article: “Clinical Applications of Contrast-Enhanced Thoracic Ultrasound (CETUS) Compared to Standard Reference Tests: A Systematic Review” by Jacobsen N et al. - Quarato, Carla Maria Irene; Venuti, Mariapia; Sperandeo, Marco (Ultraschall in der Medizin - European Journal of Ultrasound, 2020)