Although currently in limited supply due to the location proximity needed for conventional cyclotrons, 13N-ammonia is well understood and recognized as a gold standard for cardiac perfusion imaging. It is used at prominent cardiac programs at Mayo Clinic, Brigham & Women’s, Massachusetts General, UCLA, and the University of Texas.
13N-ammonia cardiac PET Radiopharmaceutical
13N-ammonia imaging offers many advantages over the dominant 99mTc-SPECT radiopharmaceutical, as well as another cardiac PET tracer, 82Rb-chloride. The table below highlights the differences between 13N-ammonia and 82Rb-chloride.
13N-ammonia, due to the low mean positron length associated before the proton annihilates, has been shown to provide clearer images potentially allowing for an improved diagnostic certainty. The following PET scan images is an example 13N-ammonia compared to 82Rb-chloride.
|Half life (min)||9.97||1.27|
|Positron energy (MeV)||1.19||95.5%|
|Positron range (mm)||0.57||2.60|
|System Resolution (mm)||6.03-6.15||6.54-8.56|
dose per study (msv)
Sterile O-16 water and
|Physiological properties||13N-ammonia||Rest flow 82Rb-chloride|
Tracer Comparison Patient Images
Abnormal 13N-ammonia PET from a patient with a 90% right coronary artery stenosis
Abnormal 82Rb PET from a patient with a 90% Proximal left anterior descending artery stenosis
Rest / Stress Protocol – CFR
Protocols for 13N-ammonia imaging can be as efficient as 82Rb-chloride if a low dose / high dose protocol is used.
1 min CT
Rest 9 mCi
Stress 20 mCi
1 min CT
13N Treadmill PET
The longer half-life of 13N-ammonia can allow for patients to be treadmill exercised as an alternative to pharmacologic stress. This provides additional imaging options for your cardiac PET program.
Recent studies utilizing treadmill 13N-ammonia stress testing have demonstrated:
- Reliable diagnostic accuracy and image quality in obese and non-obese patients. 1
- Annual event rate is consistent with previously published SPECT and PET data. 2
- Produces larger, more severe defects compared to dipyridamole stress. 3
References & Articles
- Aggarwal NR, Drozdova A, Askew JW, Kemp BJ, Chareonthaitawee P. Feasibility and diagnostic accuracy of exercise treadmill nitrogen-13 ammonia PET myocardial perfusion imaging of obese patients. Journal of Nuclear Cardiology. 2015 Dec 1;22(6):1273-80.
- Chow BJ, Al Shammeri OM, Beanlands RS, Chen L, DaSilva J, Ruddy TD. Prognostic value of treadmill exercise and dobutamine stress positron emission tomography. Canadian Journal of Cardiology. 2009 Jul 1;25(7):e220-4.
- Chow BJ, Beanlands RS, Lee A, DaSilva JN, Alkahtani A, Ruddy TD. Treadmill exercise produces larger perfusion defects than dipyridamole stress N-13 ammonia positron emission tomography. Journal of the American College of Cardiology. 2006 Jan 17;47(2):411-6.
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