Shadowing and reverberation artifacts in abdominal ultrasonography

The different features of 821 acoustic shadows recorded during abdominal US examinations were analysed to find out whether any of the features may be used in routine work to help to identify the often invisible structure casting the shadow. A constant shadow with closely spaced high level reverberation echoes is strongly suggestive of a metallic foreign body. Sharply defined shadowing without reverberation is mostly caused by stones, calcifications or scars. In a majority of cases, unsharply defined shadowing with numerous low level and sparsely spaced high level reverberation echoes is cast by gas collections. The morphology of an acoustic shadow in visceral sonography cannot alone be used as a basis for a definitive diagnosis.     

Comparison of the practical diagnostic value of different tomographic movements

The practical results of linear and circular tomography with angles of 6, 20, 30 and 45 degrees and spiral tomography were compared. The spiral proved to be suitable as a tomographic movement for different purposes. In zonography, circular movement with 6 degrees of deviation proved suitable. The linear movement presented no advantages when compared with the multidirectional movements.     

Experiences in using the auto altenator system in a teaching hospital (author's transl)]

Attention is drawn to the advantages of the auto-alternator system in the everyday assessment of films, in comparative investigations and in a teaching and training.