Uptake of 67Ga-6-mercaptopurines in Morris hepatoma-3924 A

67Ga-chloro-6-mercaptopurine and 67Ga-citrato-6-mercaptopurine complexes have been prepared and their distribution in Morris-hepatoma-3924 A-bearing rats studied. The tumour affinity of the gallium-67 compounds varies in the order: 67Ga-chloro-6-mercaptopurine greater than 67Ga-citrato-6-mercaptopurine greater than 67Ga-citrate greater than 67Ga-chloride.