the subject invention relates to the compositions for radiolabeling diethylenetriaminepentaacetic acid - dextran with technetium - 99m and for stabilizing the dtpa - dextran cold kit . the composition contains stannous chloride ions to reduce 99m tc - pertechnetate , ascorbic acid to reduce stannic ions to stannous ions to maintain a reducing environment , α , α - trehalose to add bulk and to stabilize the lyophilized composition without interfering with the radiochemical yield , and glycine to transchelate technetium - 99m under highly acidic conditions to facilitate radiolabeling dtpa - dextran with high radiochemical purity . in addition , the invention pertains to methods for making and using the compositions . the reconstitution of the lyophilized composition by 99m tc - pertechnetate , resulting in radiolabeled 99m tc - dtpa - dextran in a composition between ph 3 to 4 . this invention contains a diluent vial , which when used will shift the ph to a moderately acidic ph , which would provide less pain on injection and ease - of - use to clinical practioners for adjusting its potency .