Omega iodo fatty acid scintigraphy--what are we measuring?

In an open chested dog model utilizing dual isotope techniques (125I heptadecanoic acid and 9, 10 3H palmitic acid), sequential myocardial biopsies were performed to: validate the scintigraphic background subtraction technique for the iodo fatty acid, compare the myocardial activity time course for the fatty acids and by TLC methods determine the chemical form of the myocardial activity and to study the influence of free iodide on the overall time-activity pattern. The findings supported the method of background subtraction and demonstrated a similar activity-time course for the two fatty acids. In spite of this, approximately 30% of the myocardial activity (125I) was in the form of free iodide which suggested that the rate of diffusion of iodide may be an important kinetic element in the system. Some differences in the lipid form of the radioactivity (3H, 125I) were noted.