The general objective of this program is to develop new radiopharmaceuticals or to improve on presently available radiopharmaceuticals in order to increase the sensitivity of tumor or abscess detection. The specific objective of this aspect of the program is to develop a new Ga67 radiopharmaceutical which will take advantage of the nuclear properties of gallium and its apparent tumor affinity. This will be achieved by chromatographic analysis, in vivo distribution, and radiochemical purity determinations for a series of Ga67 chelates to better understand the factors which control the concentration of Ga67 citrate in normal tissues and blood. The decrease of this undesirable normal tissue background activity will make the Ga67 radiopharmaceutical a more valuable tool in the detection of malignancy.