Objective: Cardiac PET imaging offers the potential capability for the noninvasive measurement of arterial input function. This capability is somewhat limited, however, because of partial volume and spillover effects. The purpose of this study was to validate arterial tracer concentration measurements using PET images by assigning a region of interest (ROI) to the left ventricle, left atrium (LA), and ascending aorta.
Materials and methods: We selected [11C]CO and [13N]ammonia as tracers, because the activity of [11C]CO is primarily in the blood pool and that of [13N]ammonia primarily in myocardial tissue. Six [11C]CO and 11 [13N]ammonia PET scans were obtained in 17 subjects. Arterial tracer concentrations determined by PET were compared with those measured by well counting of arterial blood sampling obtained at the midpoint of each image acquisition.
Results: Arterial tracer concentrations as determined by LA-PET imaging correlated closely with those measured by blood sampling (r = 0.996, slope = 1.00 for [11C]CO; r = 0.841, slope = 0.974 for [13N]ammonia). Partial volume and spillover effects were minimized by assigning an ROI to the LA.
Conclusion: Arterial tracer concentrations can be measured noninvasively with cardiac PET.