[Fatty acid metabolism using C-11 palmitate: (1). Resting study].

Serial dynamic images were obtained at rest following intravenous injection of 185-370 MBq (5-10 mCi) of 11C-palmitate for 40-50 minutes in 3 normal subjects and 6 patients with coronary artery disease. Due to the rapid clearance of activity from the blood, myocardial images were observed within 5 minutes after the injection in each case. The time activity curve of each myocardial region indicates biexponential clearance. The early clearance half time (Te 1/2) was similar in normal myocardium (18.8 +/- 6.0 min), ischemic myocardium (19.3 +/- 5.8 min) and infarcted myocardium (15.5 +/- 6.0 min). The late clearance half time (Tl 1/2) was also similar among these groups (81.4 +/- 36.0, 66.9 +/- 25.7 and 57.8 +/- 37.4, respectively). However, the residual fraction (%E) was slightly lower in the ischemic myocardium (19.6 +/- 11.0%) (p less than 0.05), indicating decreased beta oxidation in the former. Although positron emission tomography using 11C-palmitate may permit assessment of fatty acid metabolism, the parameters in this study were greatly fluctuated at rest among the normal, ischemic and infarcted myocardium. Further investigations under various interventions may be warranted.