In 1964, Taplin, et al., 1) and Wagner, et al.2) developed a new radio pharmaceutical, macro-aggregated albumin labeled with iodine-131 (131I-MAA), and successfully used this material as the tracer for pulmonary scanning in man. However, their method of preparating 131I-MAA was not always satisfactory from the point of isotope yield and quality for selective pulmonary scanning. Various processes for preparation of MAA regarding isotope yield, and quality for pulmonary scanning were examined and the following series of preparation was concluded to be the best. Human serum albumin is labeled with 131I, pH is adjusting to 5.5 by buffer solution, and after sterilization, it is poured into a vial. Then this solution is heated in a boiling water bath for 20 minutes with vigorous shaking and cooled to room temperature. This is centrifuged for several minutes at 2000 -2500 r.p.m., the supernatant material is removed, and the sediment is resuspended in the buffer solution of pH 5.5.
