Labeling of tin-soaked albumin microspheres with 68Ga

A method is described for the labeling of tin-soaked human serum albumin microspheres with 68Ga. The radionuclide is a short-lived (T 1/2 = 68 min) generator product and a positron emitter; the labeled particles may be used for perfusion studies with a positron camera. The labeling procedure requires 40 min after elution of the 68Ga generator and provides a labeling efficiency of 90 +/- 5%. The in vivo stability of the particles was determined in a series of animal experiments which showed little washout of lung activity over a 2-hr period.