99mTcECD

99mTc-ECD, also known as technetium-99m ethyl cysteinate dimer or ceretec, is a radiopharmaceutical used for brain perfusion SPECT imaging. It consists of the radioisotope technetium-99m bound to an ethyl cysteinate dimer ligand. After intravenous injection, its lipophilicity allows it to cross the blood–brain barrier and enter brain tissue, where it is rapidly converted to a hydrophilic, trapped form, yielding a static distribution that reflects cerebral blood flow at the time of injection.

Imaging is typically performed about 30 to 60 minutes after injection, with optional delayed imaging possible. The radiopharmaceutical is prepared from a kit by radiolabeling pertechnetate with stannous ions; administration requires standard radiation safety procedures. The usual diagnostic activity in adults is in the 20–30 millicuries (740–1110 MBq) range, adjusted for body habitus and institutional protocol.

Clinical indications include assessment of cerebral perfusion in acute ischemic stroke and transient ischemic attack, characterization of dementia to differentiate perfusion patterns, and pre-surgical evaluation in epilepsy or brain tumor planning. The pattern of tracer uptake generally correlates with regional blood flow, and the agent is valued for relatively stable activity allowing flexible imaging times. Compared with Tc-99m HMPAO, 99mTc-ECD often offers more stable retention in brain tissue and less redistribution over time.

Safety considerations are similar to other Tc-99m radiopharmaceuticals: transient adverse effects are uncommon; hypersensitivity is possible; pregnancy and breastfeeding require caution and appropriate precautions. The exam contributes diagnostic information with established radiation dose within diagnostic nuclear medicine standards.