2311: Does liver contrast ultrasound cause the hepatocyte damage?

Abstract

Objectives: To examine if liver contrast ultrasound (US) in rats damages hepatocyte as described in published article (J Ultrasound Med 2005;24:967–974) and to investigate mechanism of hepatocyte vacuolation. Methods: Male Wistar rats were divided into eight groups (four treatments × two fixation methods, n = 4): vehicle, vehicle/liver US, Sonazoid™ (GE Healthcare), and Sonazoid™/liver US. Sonazoid™ 0.24 μL microbubbles/kg was injected intravenously and the livers were imaged with commercial US scanner at maximum output. After the treatment, rats were perfusion-fixed in either method: manual perfusion (MP) as in the article or regulated pump perfusion (PP). The liver specimens were examined with light (LM) and transmission electron microscope (TEM). Separately, vena cava pressure during the fixation was measured using untreated rats and hepatocyte vacuolation was microscopically observed. Results: Hepatocyte vacuolation was found in all rats of MP regardless of the treatments, whereas no vacuolation was found in any rats of PP. No other findings were observed in LM and TEM. Vena cava pressure, which reflects sinusoidal pressure, was significantly higher in MP than in PP, and hepatocyte vacuolation was observed only in MP. Conclusions: No histological changes attributable to contrast US were observed in rat livers. Hepatocyte vacuolation was an artifact due to higher sinusoidal pressure during perfusion-fixation.