99mTcPYP

Technetium-99m pyrophosphate (99mTc-PYP) is a radiopharmaceutical used in nuclear medicine. It consists of technetium-99m bound to pyrophosphate, a diphosphate compound. After intravenous administration, 99mTc-PYP localizes in tissues with calcium deposition or altered membrane integrity, most notably in damaged myocardial tissue and in bones undergoing turnover.

In myocardial imaging, 99mTc-PYP has historical significance for detecting acute myocardial infarction. Uptake occurs in necrotic or calcium-rich myocardial tissue and is typically assessed after a 2 to 4 hour delay, with planar gamma camera imaging or single-photon emission computed tomography (SPECT). Positive scans show focal uptake in the infarcted region, and the degree of tracer accumulation can reflect infarct size in some cases. The technique has largely been superseded for routine acute infarct evaluation by newer biomarkers and imaging modalities, but it remains described in historical literature and may be encountered in certain clinical or research contexts.

Beyond cardiology, 99mTc-PYP is also used as a bone-seeking radiopharmaceutical. It localizes to bone by binding to hydroxyapatite in areas of active bone formation, osteoblastic activity, or remodeling. Compared with more modern bone tracers such as 99mTc-MDP or 99mTc-DPD, 99mTc-PYP is less commonly employed in routine bone imaging, though it can appear in some older protocols and legacy practice.

Safety considerations for 99mTc-PYP are consistent with other 99mTc-labeled agents, including standard precautions for radiopharmaceuticals and a radiation dose appropriate to diagnostic imaging.