Evaluation of fatty liver fibrosis in rabbits using real-time shear wave elastography

Abstract

The aim of the present study was to detect the elastic modulus (stiffness) of the livers of rabbits with non-alcoholic and alcoholic fatty liver disease using real-time shear wave elastography (SWE), and to investigate the fibrosis development process in the formation of fatty liver. The stiffness of the fatty livers in rabbit models prepared via feeding with alcohol or a high-fat diet were measured using a real-time SWE ultrasound system and a 4-15-MHz linear array probe, and the liver stiffness was compared with the pathological staging of the disease. The stiffness of the liver was positively correlated with the degree of pathological change in fatty liver disease (P<0.01). The stiffness of the liver in the alcoholic fatty liver group was higher compared with that in the non-alcoholic fatty liver and control groups, and the stiffness in the non-alcoholic fatty liver group was higher than that in the control group (P<0.01). Real-time SWE objectively identified the trend in the changing stiffness of the liver and noninvasively detected the development of fibrosis in the progression of non-alcoholic and alcoholic fatty liver disease.

Keywords: elasticity; fatty liver; rabbit; real-time shear wave elastography.

Figure 1

Two-dimensional images of rabbit livers. (A) Normal rabbit liver. (B) Simple fatty liver. (C) Alcoholic fatty liver (the scale bar indicates ascites).

Figure 2

Elastography of the rabbit liver. Mean elastic modulus of: (A) the liver in a normal rabbit, 5.1 kPa; (B) a non-alcoholic fatty liver, 9.6 kPa; (C) an alcoholic fatty liver, 19.8 kPa.

Figure 3

Gross samples of rabbit livers. (A) Normal liver. (B) Non-alcoholic fatty liver. (C) Alcoholic fatty liver.

Figure 4

Hematoxylin and eosin staining of the rabbit liver observed under a microscope (magnification, ×200). (A) Liver from a normal rabbit; liver cell cords arranged in order with occasional lipid droplets in the liver cells. (B) Non-alcoholic fatty liver; a large number of large-droplet liver cells were apparent, which accounted for ~50% of the total area. (C) Alcoholic fatty liver; large-droplet liver cells accounted for ~80% of the total area, the foam-like cells are indicated by red arrows.

Figure 5

Picrosirius red (A–C) and silver (D–F) staining of the rabbit liver (magnification, ×200). Microscope images: (A) Normal rabbit liver, a small number of fibrous tissues were observed in the portal area. (B) Non-alcoholic fatty liver, fibrosis occurred around the portal area with fibrous septa forming in the lobule. (C) Alcoholic fatty liver, a large number of fibrous septa formed, which damaged the hepatic lobule. The red structures indicated by the arrows are fibrous tissues. (D) Normal rabbit liver, a small number of fibrous tissues were observed. (E) Non-alcoholic fatty liver, increased fibrosis occurred. (F) Alcoholic fatty liver, a large number of fibrous tissues were observed.

Figure 6

Correlation analysis indicated that the mean elasticity of the rabbit liver was positively correlated with the steatosis area (r=0.92, P<0.01).

Figure 7

Correlation between the mean of the mean elastic modulus values and the stage. Significant differences were observed among the different groups (P<0.05). Stage S0, normal liver essentially without fibrosis; S1, fibrosis formed in a small region, predominantly including fibers in and around the portal area; S2, a plurality of fibrous septa, where the lobular structure is roughly retained; S3, a large quantity of fibrous septa with a disordered lobular structure but without cirrhosis; S4, early cirrhosis.