technetium (99mTc) succimer (V)

Technetium (99mTc) succimer (V), also known as pentavalent Tc-99m DMSA, is a radiopharmaceutical used primarily for the diagnostic imaging of medullary thyroid carcinoma (MTC). Unlike the more common trivalent form (Tc-99m DMSA (III)), which is used for renal cortical imaging, the pentavalent form is prepared under alkaline conditions (typically by adding sodium bicarbonate to a standard DMSA kit) to achieve the +5 oxidation state of technetium. It functions as a tumor-seeking agent, with its mechanism of action believed to involve the mimicry of phosphate ions ($PO_4^{3-}$), leading to uptake in tissues with high metabolic activity or microcalcifications. It is particularly valued for detecting recurrences and metastases of MTC when calcitonin levels are elevated but conventional imaging is negative. Beyond MTC, it has been investigated for imaging soft tissue sarcomas, bone metastases, and systemic amyloidosis.

Other names

pentavalent technetium-99m dimercaptosuccinic acidtechnetium-99m dimercaptosuccinic acid (V)Tc-99m DMSA (V)pentavalent technetium-99m succimer