Kinetics of technetium 99m labelled macroaggregated albumin in humans

The uptake and elimination of 99Tcm labelled MAA were followed by gamma camera and computer over a period of 36 hours in patients undergoing lung scanning and venography. Lungs, stomach, kidneys, GI tract, bladder and thyroid showed significant concentrations of activity at various times after the injection of radiopharmaceutical, with carefully controlled labelling efficiency. There was no indication of accumulation in the liver or spleen. Activity versus time curves were constructed. The lung curve had approximately bi-exponential form with components of effective half-lives 0.88 and 4.56 h. Areas beneath the curves gave cumulated activities for each organ and, using S values (absorbed dose per unit cumulated activity) from MIRD tables, absorbed doses from self-irradiation were calculated for each organ.