Stable radiographic scanning agents

Two compositions useful in the preparation of technetium-99-based scintigraphic scanning agents are described. The first consists of a stannous salt pertechnetate reducing agent, ascorbic acid or a pharmaceutically acceptable salt or ester of ascorbic acid (no more than 25% by weight of the reducing agent) and a skeletal-specific carrier compound sleected from monor-, di-, or polyphosphonates. The second comprises an oxidized pertechnetate solution, ascorbic acid or a pharmaceutically acceptable salt or ester of ascorbic acid (no more than 0.1% by weight) and a skeletal-specific carrier compound selected from mono-, di, and polyphosphonates