MEASUREMENT OF ARTERIAL TRACER CONCENTRATIONS FROM CARDIAC PET IMAGES

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