Ultrasonographic diagnosis of mild fatty infiltration of the liver with the difference between liver and kidney echolevels

: At the same dynamic range (DR) a constant difference of echolevels was found between two materials with different acoustic impedance in any gain-setting by the phantom study. Our retrospective study in which we compared the difference between liver-kidney echolevels with the US-findings of fatty liver indicated that the difference over 10 in echoleveled by our equipment with 3.5 MHz phased array sector scan and 42 dB DR had a possibility of the fatty infiltration of the live. In our prospective study of 1452 abdominal US-studies we found 93 cases (6.5%) with the difference over 10 in echolevel. In all these patients the difference of liver-spleen CT-numbers and liver-kidney echolevels was compared. Although the liver CT-number is normally higher than the spleen, 75 of 93 patients showed the lower liver CT-number than that of the spleen, indicating fatty infiltration of the liver. The abnormal difference of echolevels were independent from the severity of fatty infiltration. Concerning the US-findings, "bright liver" (77.4%) and "masking sign" (66.7%) were more sensitive than "vascular blurring" (44.1%) and "deep attenuation" (44.1%). But for the severe fatty infiltration with the difference over -20 H.U. between liver-spleen CT numbers, the last two findings seemed very credible. The abnormal difference between liver-kidney echolevels was most sensitive (80.7%), especially in mild cases with 0 to -19 H.U. (53 in 75 cases), and very objective than the other US-findings.