Quantification of the Normal Range of Myocardial Blood Flow and Flow Reserve with 82{sup left}Rubidium versus 13{sup left}N-ammonia PET

摘要

Coronary artery disease (CAD) can be diagnosed by comparing myocardial perfusion scans with a database defining the lower limit of normal myocardial blood flow and flow reserve (MFR). Both 13{sup left}N-ammonia and 82{sup left}rubidium tracers can be used to generate flow images, however only 13{sup left}N-ammonia has been fully validated for quantifying blood flow and MFR using compartmental models. Normal databases have thus only been reported using 13{sup left}N-ammonia PET and compartmental modeling. This study aimed to establish a lower limit of normal MFR for an 82{sup left}Rb database using a compartmental model, and to determine if a simplified model would reduce the measured range of normal MFR for both tracers, improving identification of regional flow defects. 14 subjects with <5% risk of CAD underwent rest and dipyridamole stress 82{sup left}Rb and 13{sup left}N-ammonia dynamic PET imaging in a randomized order within a 2-week period. MBF was quantified using a one-compartment model for 82{sup left}Rb, and a two-compartment model for 13{sup left}N-ammonia. A simplified model was used to estimate the net retention rate for both tracers. Model-specific extraction functions were determined to obtain flow estimates. It was found that the retention reserve variability the was lowest and was equivalent for both tracers (± 15% globally, ± 16% regionally) indicating that the retention model may be preferable for detection and localization of flow reductions. The two-compartment model for 13{sup left}N-ammonia had the smallest normal MFR range (mean-2sd = 2.27 globally, 1.48 regionally) confirming its precision for absolute flow quantification.