We have recently developed an apparatus for measuring the sound velocity and attenuation
coefficient in the liver by a crossed beam method for use in the non-invasive quantitative diagnosis
of fatty liver. The results obtained with it were as follows.
The sound velocity was 1,575±19 m/sec in the 12 patients with normal livers and 1,531±26 m/sec
in the 20 patients with fatty livers. In the patients with fatty liver, the sound velocity was
significantly lower than in those with normal livers. Concerning the relationship between the fat content
and the sound velocity, a significant negative correlation of r=-0.73 was noted. The highest
attenuation coefficient was recorded in fatty livers. If a liver-kidney contrast was recognized by US,
in cases with a normal sound velocity, fatty deposits were scarcely present. Thus the sound velocity
measurement was highly specific for fatty liver.
Liver biopsy was conducted in 6 patients with chronic inactive hepatitis and in 20 patients with
fatty liver. Liver tissue specimens 15 mm long were stained with Amido-Black 10B. The area ratio
of the unstained portion (that is, the fat deposits) was determined using a texture analyzing system
(manufactured by Leitz Co.). These results were compared with the hepatic sound velocity and
attenuation coefficient. By simultaneous measurement of the hepatic sound velocity and attenuation
coefficient, the sensitivity of diagnosis was increased. The accuracy of diagnosis of the degree of
fatty change also proved to be very high.