Coupling of /sup 11/C-acetate and /sup 13/N-ammonia for measurement of myocardial blood flow in normal rats using the Sherbrooke PET scanner

Regional myocardial blood flow (MBF) can be assessed non-invasively with dynamic PET and /sup 13/N-ammonia or /sup 11/C-acetate. The latter can also be used to estimate the myocardial oxygen consumption (MVO2) from the same time-activity curve. In this work, we explore the feasibility of such techniques for evaluating myocardial parameters in normal rats (/spl sim/350 g) using the Sherbrooke small animal PET scanner. Scans were acquired in list mode for /sup 13/N-ammonia and /sup 11/C-acetate as two consecutive 15 minute dynamic scans separated by a 5 minute interval, without moving the rat from the scanner. Three-compartment models were applied to regions of interest (ROIs) defined on four segments of the myocardium. /sup 13/N-ammonia and /sup 11/C-acetate time-activity curves were fitted for three and four rate constants, respectively, plus blood volume. A reasonable agreement is observed between MBF estimates extracted from /sup 13/N-ammonia and /sup 11/C-acetate. MVO2 estimates, as given by the k/sub 2/ rate constant, were obtained with good reproducibility, indicating that myocardial metabolism can reliably be assessed concurrently with MBF using /sup 11/C-acetate. In conclusion, it is demonstrated that myocardial blood flow and oxygen consumption can be evaluated in rats with the Sherbrooke small animal PET scanner through high-rate, list-mode, dynamic imaging and kinetic modeling of /sup 13/N-ammonia and /sup 11/C-acetate.