Obesity and liver disease: evaluation of fatty infiltration of the liver using ultrasonic attenuation.

We developed an in vivo ultrasonic attenuation measurement system with which we attempted to evaluate the degree of fatty infiltration in the liver. In an animal study, fatty liver was induced in rabbits, and ultrasonic radiofrequency waveforms from the liver were obtained using a 10 MHz A mode transducer. Frequency-dependent attenuation of the ultrasound, which was correlated with total lipid content, was calculated using a spectral difference method. In a human study, ultrasonic waveforms were obtained using a 3.5 MHz transducer. Frequency-dependent attenuation also showed a significant correlation with the grading of fatty infiltration of the liver. These results suggested that fatty infiltration of the liver could be evaluated quantitatively and noninvasively using frequency-dependent attenuation of the ultrasound.