Low density microspheres and their use as contrast agents for computed tomography

Claim 2

A kit for computed tomography imaging of the gastrointestinal region or other body cavities comprising low density biocompatible synthetic polymeric or copolymeric microspheres having an internal void volume of at least about 75% of the total volume of the microsphere, and a thickening or suspending agent.

Claim 3

A kit according to claim 1 wherein said microspheres comprise synthetic polymers or copolymers prepared from the group of monomers consisting of acrylic acid, methacrylic acid, ethyleneimine, crotonic acid, acrylamide, ethyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, lactic acid, glycolic acid, ε-caprolactone, acrolein, cyanoacrylate, bisphenol A, epichlorhydrin, hydroxyalkylacrylates, siloxane, dimethylsiloxane, ethylene oxide, ethylene glycol, hydroxyalkyl-methacrylates, N-substituted acrylamides, N-substituted methacrylamides, N-vinyl-2-pyrrolidone, 2,4-pentadiene-1-ol, vinyl acetate, acrylonitrile, styrene, p-amino-styrene, p-amino-benzyl-styrene, sodium styrene sulfonate, sodium 2-sulfoxyethyl methacrylate, vinyl pyridine, aminoethyl methacrylates, 2-methacryloyloxy-trimethylammonium chloride, N,N'-methylenebisacrylamide, ethylene glycol dimethacrylates, 2,2'-(p-phenylenedioxy)diethyl dimethacrylate, divinylbenzene, triallylamine, and methylenebis-(4-phenyl-isocyanate).

Claim 4

A kit according to claim 2 wherein said microspheres comprise synthetic polymers or copolymers prepared from the group of monomers consisting of acrylic acid, methacrylic acid, ethyleneimine, crotonic acid, acrylamide, ethyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, lactic acid, glycolic acid, ε-caprolactone, acrolein, cyanoacrylate, bisphenol A, epichlorhydrin, hydroxyalkylacrylates, siloxane, dimethylsiloxane, ethylene oxide, ethylene glycol, hydroxyalkyl-methacrylates, N-substituted acrylamides, N-substituted methacrylamides, N-vinyl-2-pyrrolidone, 2,4-pentadiene-1-ol, vinyl acetate, acrylonitrile, styrene, p-amino-styrene, p-amino-benzyl-styrene, sodium styrene sulfonate, sodium 2-sulfoxyethylmethacrylate, vinyl pyridine, aminoethyl methacrylates, and 2-methacryloyloxytrimethylammonium chloride.

Claim 5

A kit according to claim 1 wherein said microspheres comprise synthetic polymers or copolymers selected from the group consisting of polyacrylic acid, polyethyleneimine, polymethacrylic acid, polymethylmethacrylate, polysiloxane, polydimethylsiloxane, polylactic acid, poly(ε-capro-lactone), epoxy resin, poly(ethylene oxide), poly(ethylene glycol), polyamide, polyvinylidene-polyacrylonitrile, polyvinylidene-polyacrylonitrile-polymethylmethacrylate and polystyrene-polyacrylonitrile.

Claim 6

A kit according to claim 4 wherein said microspheres comprise polyvinylidene-polyacrylonitrile copolymer.

Claim 7

A kit according to claim 1 wherein the microspheres are prepared by a heat expansion process.

Claim 8

A kit according to claim 1 wherein the microspheres are gas-filled.

Claim 9

A kit according to claim 7 wherein said gas in said gas-filled microspheres is selected from the group consisting of carbon dioxide, oxygen, nitrogen, xenon, argon, neon, and helium.

Claim 10

A kit according to claim 1 wherein said thickening and suspending agents are selected from the group consisting of alginates, xanthan gum, guar, pectin, tragacanth, bassorin, karaya, gum arabic, casein, gelatin, cellulose, sodium carboxymethylcellulose, methylcellulose, methylhydroxycellulose, bentonite, and colloidal silicic acid, carrageenin, polyethylene glycol, polypropylene glycol, and polyvinylpyrrolidone.

Claim 11

A kit according to claim 1 wherein said kit is for imaging said gastrointestinal region, and wherein said kit further comprises components selected from the group consisting of anti-gas agents, osmolality raising agents, gastrointestinal transit agents, and gas-forming agents.