[Abdominal sonography in small animals. I. Physical fundamentals, apparatus technic].

Ultrasound waves result from the utilization of the reverse "piezo-electric effect". The diagnostic ultrasound uses the impulse-echo method. Interfaces between tissues of differing acoustic impedance reflect part or all of the sound beam back towards the transducer. The returning echos are converted into electrical signals, which are analysed according to the strength and depth of reflection and finally displayed on a monitor as amplitudes or brightness values. Scanning is performed with mechanical sector or electrical linear array transducers. The pros and cons of the different scanners are discussed and at least some advice for the choice of an ultrasound machine is given.