Coronary flow and flow reserve by PET simplified for clinical applications using rubidium-82 or nitrogen-13-ammonia

To validate routine, noninvasive determination of absolute myocardial perfusion and coronary flow reserve (CFR), cardiac PET was performed in animals using a simplified imaging protocol, high-dose dipyridamole and a simplified quantitative algorithm specific for 82Rb and 13N-ammonia.

One hundred thirty-five PET scans were obtained in eight dogs after intravenous 13N-ammonia or 82Rb using serial dynamic PET or a simple two-image dataset. A simple flow model using the two-image dataset was developed for each radionuclide to account for varying arterial input function, flow-dependent myocardial extraction and increased permeability surface area (PS) product due to capillary recruitment at high flows not incorporated into previous models. Myocardial perfusion by the simple model was compared to standard, complete, two-compartment kinetic models validated by comparison to electromagnetic flow meter.

For 13N-ammonia, myocardial perfusion by the simple PET model correlated with that by complete compartmental analysis of multiple serial PET images with r = 0.94, slope = 0.96; CFR by compartmental analysis correlated with CFR by electromagnetic flow meter with r = 0.94, slope = 0.97. For 82Rb, myocardial perfusion determined by the simple model correlated with that determined by complete compartmental analysis of multiple serial PET images with r = 0.98, slope = 1.06; CFR determined by compartmental analysis correlated with CFR by electromagnetic flow meter with r = 0.88, slope = 1.13.

A simplified PET protocol using 13N-ammonia or 82Rb and simple flow models provide noninvasive measurement of CFR up to six times baseline flow throughout the heart and diagnostic image quality for routine clinical application.