Composotions and methods for radiographic imaging

DETAILED DESCRIPTION The present invention is a micellar iodine-containing block copolymer (MICBC) useful as a radiographic imaging agent.
These micelle-forming block copolymers include a hydrophilic polymer linked to a hydrophobic polymer that includes a backbone incorporating radiopaque molecules.
The imaging agent incorporates high levels of radiopaque molecules, which are normally insoluble, into the backbone of the hydrophobic polymer.
The hydrophilic polymer imparts solubility to the imaging agent, and also allows it to avoid quick uptake by the reticuloendothelial system (RES).
The micellar imaging agent thus allows high quantities of radiopaque molecules, adequate to permit detection with current imaging techniques, to be administered to an individual.
The micellar imaging agents are of sufficient size (approximately 100-150 nm) that they do not quickly diffuse into the interstitial space upon intravenous administration.
Therefore, using MICBCs, radiographic imaging can be performed for longer periods of time than with low molecular weight contrast agents.
MICBCs are especially useful for radiographic imaging of the blood pool; that is, the image of any vascularized region of the body can be enhanced by in vivo administration of MICBCs.
Additionally, despite the high molecular weight of the MICBCs when administered as micelles, MICBCs are excreted via the kidney after the micelles break down.
After MICBCs are administered intravenously, they are diluted in the bloodstream, and the micelles ultimately dissociate into individual block copolymer chains, or unimers.
These unimers are of low molecular weight, and are therefore efficiently eliminated from the body.
The rate at which MICBCs dissociate in vivo is a function of the molecular weights of the hydrophilic polymer and the backbone of the hydrophobic polymer, which together form the block copolymer.
At the optimal molecular weights of each of these two polymer chains, the micellar structure exists for forty minutes to two hours once introduced into bodily fluids, during which time radiographic imaging can be performed