To investigate the changing law of histopathological features in the recently ablated area after ultrasound-guided microwave ablation(MWA)of rat liver with time and its influence.

A MWA model of the liver of SD rats was established, and MWA was performed on the liver sites of SD rats under ultrasound guidance.According to the different times after the operation, SD rats were randomly divided into immediately post-operative MWA, post-operative MWA group of 2 h, post-operative MWA group of 6 h, and post-operative MWA group of 12 h, with 6 rats in each group.The volume of ablation area and liver ablation ratio, pathological morphology of liver tissue in the ablation area, apoptosis and inflammatory cytokine levels were observed in SD rats in each group.

Ultrasound evaluation showed that the volume of ablation area and liver ablation ratio decreased with the increase of time after MWA, and there was a correlation between the postoperative time and liver ablation ratio(r=-0.7714, P<0.0001). HE staining showed that the tissue of the ablation area of the rat liver showed obvious necrotic structures with the increase of the postoperative time after MWA.TUNEL staining showed that the apoptosis level of the tissue cells in the ablation area of rat liver increased with the increase of time after MWA, and there was a correlation between the two(r=0.9645, P<0.0001). The levels of inflammatory cytokines IL-1βand IL-18 in the tissues of the ablation area of rat liver decreased with the increase of the time after MWA, and there was a correlation between the levels of IL-1β(r=-0.9192, P<0.0001)and IL-18(r=-0.8225, P<0.0001)with the time after MWA.

After ultrasound-guided MWA on the liver of SD rats, there is a negative correlation between the postoperative time and the ablation ratio of the liver, and the levels of inflammatory cytokines IL-1βand IL-18 in the tissue of the ablation area, and a positive correlation between the postoperative time of the MWA and the rate of apoptosis in the tissue of the ablation area.