Ultrasound image properties influenced by abdominal wall thickness and composition.

The influence of different examination conditions on the ultrasound B-scan was investigated using a tissue-mimicking phantom and a computerized ultrasound system. Several fat-muscle combinations simulated differences in abdominal wall thickness and composition. The analysis of the ultrasound images was performed by use of statistical parameters applied in ultrasound tissue characterization, thereby the influence of the abdominal wall thickness and composition on the ultrasound image brightness, microtexture, and macrotexture (image sharpness) was studied. An increasing fat path caused a decrease in ultrasound image brightness and microtexture. The macrotexture was largely unaffected. Muscle tissue alone had a weak influence on the microtexture parameters. Our results show that an increase in the fat layer of the abdominal wall causes a darker, unsharp image and may lead to false diagnoses, especially in adiposity. Furthermore, fat-muscle combinations caused a decrease in image brightness and contrast. The decrease in these image properties was dependent on the thickness of the combination as well as on the frequency of the transducer. The effects were stronger for high-frequency transducers.