Cyclotron-produced. Must be used on-site due to the 9.97-minute half-life — cannot be shipped from an off-site cyclotron. This limits availability to PET centers with an in-house cyclotron.
N-13 ammonia crosses the myocardial cell membrane and is metabolized to glutamine, trapping it within cells. Uptake is proportional to myocardial blood flow.
Advantages:
- Excellent myocardial image quality with high target-to-background ratio
- Allows absolute flow quantification and myocardial flow reserve (MFR) calculation
- Gold standard against which other perfusion agents are often compared in research
Limitations:
- Requires on-site cyclotron — limits use to academic/research centers
- 10-minute half-life demands rapid preparation and precise timing
- High liver uptake on early images can overlap inferior wall (wait 5–10 min post-injection before imaging)
For centers without a cyclotron, Rb-82 (generator-based) provides similar PET perfusion capability without on-site production. F-18 flurpiridaz may further expand access as a cyclotron-produced but shippable agent.