Citation, DOI, disclosures and article data
Citation:
Sciacca F, Murphy A, Ammonia (N-13). Reference article, Radiopaedia.org (Accessed on 17 Apr 2024) https://doi.org/10.53347/rID-73988
13NH3 is a PET tracer used for studies of myocardial perfusion imaging. It is produced in a cyclotron by proton irradiation of the enriched water of the oxygen-16. Ammonia (N-13) is administered intravenously, at a dose of 10-20 mCi (370-740 Mbq) in adults; its physical half-life is 10 minutes.
Extraction and retention
Ammonia, at physiological pH, is found in its cationic form, 13NH4+ (ammonium ion); it is, therefore, probable that it passes the cell membrane of the myocyte through the sodium-potassium pump (Na+/K+) active transport mechanism. Inside the cell, it is then converted, together with glutamic acid, into glutamine (N-13).
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