Ultrasound in the diagnostics of fatty liver in obesity

Chronic diffuse liver diseases (CDLD) produce the characteristic ultrasound (US) image of bright liver. On the basis of liver attenuation, two major appearances are seen, the low and the high attenuation types. It was proved previously that high attenuation is associated with fatty liver, and subcutaneous fat thickness (SCF) correlates with the attenuation. The cut-off value of attenuation and SCF was searched for the differentiation of the two attenuation types and that of the normal livers. Four hundred and forty-one cases (proved by histology) were examined by US. Of these, 132 normal livers, 176 low attenuation type, and 133 high attenuation type bright livers were found. The cut-off level of attenuation, determined by frequency distribution analysis, was defined as 1.1 dB/cm/MHz, between fatty liver and low attenuation type bright liver and normal liver. The cut-off value for SCF could not be determined. It is concluded that, above the cut-off point of attenuation, the diagnosis of fatty liver can be established without liver biopsy. SCF values give additional comfirmational data.