Patent ID: 7345150

Claim:
A composition comprising a polyethylene glycol-albumin colloid composition having Cys-34 preserved as a thiol (PEG-Alb Cys-34 ), wherein PEG-Alb Cys-34 has a hydrodynamic radius that is sufficiently large to preclude the composition from leaking through a patient's capillaries and is 13 fold larger than the hydrodynamic radius of an albumin protein, wherein the PEG-Alb Cys-34 is human albumin or bovine serum albumin modified with an indicator reagent; wherein the indicator reagent is a first dye having an emission and excitation spectra and a second dye having an emission and excitation spectra, wherein the emission and excitation spectra of the second dye is distinct from that of the first dye.