Evaluation of ultrasonic attenuation in diffuse diseases of spleen and liver.

Ultrasonic attenuation has been measured using frequency domain signal processing in clinical trials of patients with liver and spleen diseases. By comparing the variance encountered in local measurements and in measurements at a number of adjoining sites, the need for averaging over large volumes of tissue to avoid the effects of large fluctuations is established. In spleens of patients with myelofibrosis, no correlation between fibrosis and attenuation was found. However it was found that variations in splenic volume were accompanied by inverse changes in attenuation, most likely due to blood pooling. A correlation was found between splenic blood flow per unit organ volume and attenuation. In cirrhotic livers, attenuation was significantly increased with fatty infiltration, but only slightly increased in livers containing minimal fat. These findings tend to reduce the probability of finding successful clinical applications for attenuation slope measurements.