Planar myocardial imaging in the baboon model with iodine-123-15-(iodophenyl)pentadecanoic acid (IPPA) and iodine-123-15-(P-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP), using time-activity curves for evaluation of metabolism.

The purpose of this study was to compare by planar myocardial scintigraphy the kinetics of iodine-123-15-(iodophenyl)pentadecanoic acid (123I-pPPA and 123I-oPPA), and of iodine-123-(p-iodophenyl)-3-R,S-methyl-pentadecanoic acid (BMIPP), firstly in normal baboons, and subsequently after blocking fatty acid oxidation by a carnitine palmitoyl transferase I(CPT1) inhibitor. The induced changes in myocardial metabolism were reflected in the dynamic behaviour of the three tracers. pPPA and oPPA to a large extent, provided information on beta-oxidation changes in the myocardium: beta-oxidation participation changed from 47% and 50%, respectively to 17% and 23% after inhibition. BMIPP provided better images and reflected largely on changed tracer incorporation into the neutral lipid pools. The beta-oxidation contributed only about 10% towards the metabolic pathway of BMIPP. The information obtained in this study could help determine the tracer of choice for SPECT, whereby myocardial viability could optimally be revealed.