Fasting for 24 h reveals liver microsteatosis after continuous i.v. infusion of milacemide in the rat

Establishment of experimental hepatic steatosis model in rabbits and non-invasive quantitative ultrasonic diagnosis of fatty liver disease

AIM: To explore the non-invasive, quantitative ultrasonic diagnostic criteria of fatty liver diseases by establishing a rabbit model of hepatic steatosis and measuring ultrasonic integrated backscatter (IBS) and gray scale (GS).

METHODS: Forty healthy New Zealand rabbits were randomly divided into normal control and three experimental groups. Hepatic steatosis was induced by high fat and sugar diet plus drinking water containing five percent of ethanol. Seven patients with mild or severe hepatic steatosis were also recruited in the study. The steatosis, inflammation, and fibrosis of the rabbits' and patients' liver were evaluated by several histological staining methods including Sudan IV, H&E, and Masson's Trichrome staining. Hepatic steatosis was graded as simple steatosis, steatohepatitis, fibrosis and cirrhosis. Liver IBS including average image intensity (AII) and peak-peak intensity, and GS were measured using HP Sonos 5500 image system. The data were analyzed with one-way ANOVA.

RESULTS: Hepatic AII was associated with the aggravated hepatic steatosis in near areas of the rabbit liver, i.e., normal control < mild fatty liver < moderate fatty liver < severe fatty liver (P < 0.0001). Significant differences were observed between AII of steatohepatitis and simple hepatic steatosis. In the patients, IBS was more accurate in the reflection the severity of the liver pathology than routine ultrosonic examination (85.7% vs 57.1%, P < 0.05), and significant differences of AII were observed between mild and severe hepatic steatosis (P < 0.0001, 0.001 or 0.05). The liver GS were markedly increased in the moderate and severe fatty liver as compared with that in normal control and mild fatty liver. Correlation analysis showed that GS and AII were consistently increased as the disease aggravated in the near area of the left and right liver lobes of the animals (r₁ = 0.442 21, P₁ = 0.0012; r₂ = 0.335 73, P₂ = 0.0160).

CONCLUSION: Rabbit fatty liver models can be developed in a short time by high fat and sugar diet plus alcohol. Hepatic IBS and GS intensity can reflect the grades of hepatic steatosis, inflammation and fibrosis, so they may serve as reliable non-invasive tools for the quantitative diagnosis of fatty liver disease.