Patent ID: 8747812

Claim:
A stable aqueous negative contrast agent for CT imaging of the gastrointestinal tract, wherein said stable aqueous negative contrast agent is a suspension of low CT density gas microbubbles that are coated by one or more stabilization agents and suspended in an aqueous hydrogel matrix, the components including: hydrogel matrix from 0.01 to 1 weight percentage, one or more stabilization agents from 0.1 to 5 weight percentage, and water, the stable aqueous negative contrast agent including the gas microbubbles at a volume concentration in the hydrogel matrix of 5 to 50% at 25° C. under one atmosphere pressure, wherein during use the hydrogel matrix distends the intestinal wall and the microbubbles that are coated by one or more stabilization agents decrease the CT density of the intestinal lumen.