[Propagation of ultrasound in tissue and principles of ultrasound imaging]

Sonography is based on multiple interactions between ultrasonic waves and the tissue during propagation. Therefore, ultrasound images contain more information than the mere visualization of the anatomic structures. Assessing the different echogenicity and texture of tissue regions yields additional information about the pathologic tissue alterations. Precise interpretation requires knowledge of the whole process of image generation. This also applies for the adjustment of system parameters for image improvement. This article explains the phenomena of ultrasound propagation in tissue and the principles of ultrasound image generation-from the scan head to the image on the screen.