Regional lumped constant estimation in F-18-FDG Myocardial PET

For a dog with acute myocadial infarction, regional lumped constant (LC) of both infarcted and normal areas were estimated. Myocardial glucose uptake rates (MGU) of these areas were calculated and compared with that calculated from conventional LC. F-18-FDG PET scans were performed on 8 dogs (15-18 Kg) induced with myocardial infarction using ECAT EXACT47 (Simense-CTI, Knoxville, U.S.A.) After 20 mins transmission scan, dynamic F-18-FDG myocardial PET scans (15 sec x 8, 30 sec x 2, 120 sec x 2, 180 sec x 1 300 sec x 4, 600 sec x 1) were performed simultaneously with a intravenous injection of 37 MBq F-18-FDG. Input functions were obtained by drawing region of interest (ROI) on the left ventricle and tissue time activity curves (TACs) for the infracted and normal myocardium were obtained. Rate constants (K1, k2, k2, k4) in three compartment model were estimated and regional LC was calculated by substituting these rate constants into the equation used by Wiggers. Regional LC for normal mycardium was 0.63±0.07 and MGU was 0.79±0.21 p mol/g/min, while MGU with LC fixed at 0.67 was 0.75 ±0.24 p mol/g/min. Regional LC for the infarctecd mycardium was 0.58±0.12 and MGU was 0.30±0.14 p mol/g/min, while MGU with LC fixed at 0.67 was 0.27±0.13 p mol/g/min. Since LCs are various according to the myocardial regions, it would be appropriate to calculate MGU with regional LC rather than fixed LC