An improved model for the measurement of myocardial perfusion in human beings using N-13 ammonia

• Published in: Journal of nuclear cardiology 2005-05, Vol.12 (3), p.311-317
• Main Authors: Hickey, Kathleen T., Sciacca, Robert R., Chou, Ru-Ling, Rodriguez, Oswaldo, Bokhari, Sabahat, Bergmann, Steven R.
• Format: Article
• Language: English
• Subjects: Adult; Algorithms; Ammonia; Blood Flow Velocity - physiology; Computer Simulation; Coronary Circulation - physiology; Coronary Vessels - diagnostic imaging; Exercise Test; Female; Humans; Image Enhancement - methods; Image Interpretation, Computer-Assisted - methods; Male; Mathematical models; Medical research; Models, Cardiovascular; myocardial blood flow; Nitrogen Radioisotopes; oxygen 15 water; Oxygen Radioisotopes; Positron emission tomography; Radionuclide Imaging; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Water
• ISSN: 1071-3581; 1532-6551
• DOI: 10.1016/j.nuclcard.2005.01.010

Oxygen 15 water and nitrogen 13 ammonia are widely used for the quantitative measurement of myocardial perfusion with positron emission tomography. However, blood flow obtained with N-13 ammonia by use of the conventional 2-compartment model frequently underestimates flow by 30% to 50% compared with O-15 water. We hypothesized that this discrepancy is a result of the model configuration of N-13 ammonia and investigated changes to the mathematical model to determine whether more accurate measurements of perfusion could be obtained. Twelve healthy volunteers were sequentially studied with O-15 water and N-13 ammonia at rest and during maximal coronary vasodilation with adenosine. Perfusion measurements obtained with the conventional and modified models were compared with values obtained with O-15 water. The conventional N-13 ammonia model underestimated flow by 37% ± 16% at rest and by 20% ± 24% with stress when compared with flows obtained with O-15 water. The modified model yielded flow values closer to the line of identity than the conventional model (y = 1.07x + 0.04 vs y = 0.69x + 0.08; respectively; P < .01). Model changes made N-13 ammonia myocardial blood flow estimates more comparable to those obtained with O-15 and may allow for better comparison of flows obtained with these two tracers in the future. Further efforts are warranted to evaluate the accuracy of flow models in human subjects.