Assessment of liver and kidney enhancement with a perfluorocarbon vapor-stabilized US contrast agent

Rationale and Objectives. The authors evaluated the time-echogenicity response of liver, kidney, and implanted VX2 tumor after injection of a microbubble contrast medium and assessed use of an avascular lesion as an internal standard. Materials and Methods. Twenty-one New Zealand White rabbits were studied. To evaluate use of an internal standard and the dose-response relationship, nine rabbits with 7-day-old avascular liver lesions created by alcohol ablation received 0.1, 0.25, 0.5, and 1.0 mt of AF0145, a microbubble contrast agent. To evaluate tumor echogenicity, 12 rabbits implanted with VX2 tumor in the liver (six also underwent alcohol ablation) received 0.5 mL of AF0145. Videodensitometry was used to analyze echogenicity changes over 10 minutes. Results. Echogenicity of the alcohol-ablated liver was not affected by contrast material administration. Liver and kidney echogenicity relative to ablation increased linearly with dose, peaking 1 minute after injection and decaying to baseline over 9 minutes. Contrast material administration defined the size and margins of VX2 lesions more clearly. In the arterial phase, the tumor rim was hyperechoic relative to surrounding liver, becoming isoechoic during the portal venous phase then hypoechoic during the late phase parenchymal phase. Conclusions. Lesions created by alcohol ablation can he used as an internal standard for quantitative analysis of adjacent tissues. AF0145 enhances perfused tissues, including vascular tumors, at gray-scale, real-time ultra-sonography and enhances the liver.