Particulate contrast media derived from non-ionic water soluble contrast agents for CT enhancement of hepatic tumors

A method for producing a precursor for a radiopaque particulate contrast agent for selectively detecting lesions in the liver and spleen, said contrast agent being biodegradable into non-ionic by-products, said method comprising the steps of:

• providing a non-ionic, water soluble, radiopaque contrast agent comprising an aromatic ring bonded to at least one radiopaque substituent and to at least one amide group at the carbon or the nitrogen of the amide moiety, said amide group having a substituent selected from the group consisting of an aliphatic 1,3-diol and a vicinal diol;
• thoroughly mixing said contrast agent with an activating agent and a polar aprotic solvent in the presence of a catalyst;
• reacting said mixture for a time and at a temperature sufficient to form said precursor by changing said diol substituent on said amide into a compound selected from the group consisting of a cyclic carbonate, a carbamate, and mixtures thereof;
• and
• separating said precursor from said polar aprotic solvent.