Ultrasound backscatter and attenuation in human liver with diffuse disease

Ultrasound backscatter and attenuation in the liver were measured in patients with diffuse liver disease and in 35 volunteers who had no history of liver ailments. Measurements were done using radiofrequency (RF) echo signals derived from a clinical scanner; a reference phantom was scanned to account for effects of gain, transmit-receive frequency response and transducer beam patterns on echo data. The mean backscatter coefficient at 3 MHz in livers of 7 patients with fatty infiltration was 6.8 x 10(-3) cm(-1)sr(-1) compared to a mean of 0.5 x 10(-3) cm(-1)sr(-1) in healthy patients. Mean attenuation at 3 MHz was 2.54 dB/cm in fatty livers compared to 1.66 dB/cm in healthy patients. A total of 7 patients with end-stage liver disease (cirrhosis) had attenuation values similar to those in the healthy group, and their mean liver backscatter was somewhat greater than the mean backscatter for healthy livers. Quantitating both backscatter and attenuation should be considered for detecting fatty infiltration; additional processing methods are needed to differentiate cirrhotic changes on the basis of acoustic signals.