Cardiac PET Overview

Cardiac Positron Emission Tomography is emerging as the preferred test for the diagnosis of coronary artery disease (CAD). Despite the clear majority of nuclear cardiology procedures being performed on Single Photon Emission Computed Tomography (SPECT) imaging devices, there are several advantages of PET over SPECT: lower radiation dose to the patient, improved tracer kinetics, well established attenuation correction, coincidence detection of emitted events, and the ability to perform routine accurate coronary blood flow measurements.

These advantages correlate with improvements in procedure accuracy and sensitivity compared to SPECT, particularly for heavier patients, where breast, chest wall, and diaphragmatic attenuation interfere with conventional SPECT.


N-13 Ammonia cardiac PET imaging with coronary flow reserve (CFR) provides high spatial and contrast resolution images. The high-resolution PET detectors optimize the low kinetic energy of N-13 Ammonia producing sharp myocardial perfusion images. The statistically high-count 13N-ammonia images of the myocardium are a result of the rapid clearance from blood pool, high first-pass extraction, high retention in the myocardium, and a relatively long physical half-life. N-13 Ammonia consistently produces high-quality diagnostic studies regardless of patient size or gender.

Sensitivity Specificity Positive
N-13 Ammonia MPI PET/CT with CFR 1 96 80 93 89 92
99mTc MPI CZT SPECT 2 87 67 92 53 83


N-13 Ammonia with CFR is a strong predictor of patient outcomes. CFR offers improved risk stratification and has proven to be an independent predictor of adverse outcomes. The results of one study on the long-term prognostic value of N-13 Ammonia with CFR demonstrated that an abnormal CFR, regardless of normal or abnormal perfusion images, was associated with higher adverse cardiac events. Conversely, a normal perfusion along with a normal CFR suggested a 3-year “warranty” period. 3

Annual Event Rate 3


N-13 Ammonia offers the lowest radiation dose to the patient compared to all other SPECT and PET myocardial perfusion radiopharmaceuticals. High sensitivity PET and PET/CT scanners with 3D imaging capabilities allow for half-dose protocols and therefore can routinely provide a complete N-13 Ammonia rest/stress CFR study with as little as 1 mSv. or less radiation exposure to the patient. 4

MPI Protocol 5 Average effective
MPI dose (mSv)
Average effective dose
from CT attenuation
correction (mSv)
Average total
effective dose (mSv)
201TI/99mTc-SPECT 29.3 0.5 30.3
Two-day 99mTc-SPECT 12.8-15.7 0.5 13.8-16.7
One-day 99mTc-SPECT 9.9-11.4 0.5 10.9-12.4
Stress-only 99mTc-SPECT 7.1-8.0 0.5 8.1-9.0
82Rb PET (2D) 3.7 0.5 4.2
N-13 Ammonia (2D) 2.2 0.5 2.7


N-13 Ammonia with CFR provides significant value to the overall management of coronary artery disease (CAD). N-13 Ammonia with CFR reduces unnecessary diagnostic procedures and can provide direction for both interventional and medical therapies. A study utilizing N-13 Ammonia with CFR demonstrated that the N-13 Ammonia CFR results had a direct impact on patient management in 78% of the patients while reducing the overall cost of managing coronary artery disease, even with an increase in the diagnostic imaging cost attributed to the N-13 Ammonia PET/CT study. 6

Patient Management 6



  1. Fiechter et al. “Diagnostic Value of 13N-Ammonia Myocardial Perfusion PET: Added Value of Myocardial Flow Reserve” J Nucl Med 2012; 53:1230-1234
  2. Fiechter et al. “Nuclear myocardial perfusion imaging with a novel cadmium-zinc-telluride detector SPECT/CT device: first validation versus invasive coronary angiography” Eur J Nucl Med Mol Imaging 2011; 38:2025-2030
  3. Herzog et al. “Long-Term Prognostic Value of 13N-Ammonia Myocardial Perfusion Positron Emission Tomography” JACC 2009; 150-6
  4. Dorbala et al. “Approaches to Reducing Radiation Dose from Radionuclide Myocardial Perfusion Imaging” J Nucl Med 2015; 56:592-599
  5. Di Carli et al. “Cardiac PET/CT for the Evaluation of Known or Suspected Coronary Artery Disease” Radiographics. 2011;31:1239-1254
  6. Siegrist et al. “13N-ammonia myocardial perfusion imaging with a PET/CT scanner: impact on clinical decision making and cost-effectiveness” Eur J Nucl Med Mol Imaging 2008; 35(5):889-895


Learn how coronary flow reserve is a key clinical application and diagnostic tool.

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