**1.4 Ultrasound techniques and procedures**

The principles of ultrasonography are complex. The US picture is generated by ultrasound penetration into the human body. US are reflected as echoes and converted by the transducer into signals. The ultrasound image is multimodal. There are multiple US procedures systematized into "clinical applications" and the information obtained is tissular ("morphometric" type) and vascular ("hemodynamic "type). Finally, US examination is a "real time" procedure which reflects the movements of the organs. It is mandatory to connect the US information to the clinical and functional-biochemical data in order to obtain the final diagnosis.
