The development of radioiodinated 3-methyl-branched fatty acids for evaluation of myocardial disease by single photon techniques

The measurement of regional myocardial “release-rates” after intravenous administration of iodine-123-labeled fatty acids such as 17-iodoheptadecanoic acid (HDA) [1–6] and 15-(p-iodophenyl)pentadecanoic acid (IPP) [7–13] has been well documented. These agents have proven useful to probe regional aspects of fatty acid metabolism in ischemic heart disease. Studies with (123I)HDA have als shown an unusual and unexpected relation between uptake and release rates in cardiomyopathies [14]. These agents were designed to exhibit extraction similar to natural fatty acids and enter the β-oxidation catabolic chain. Since free radioiodide and short-chain metabolites are released rapidly, the measurement of regional “release-rates” is presumed to reflect the metabolic activity of the myocardial tissue. The structures of these agents and structurally-modified fatty acids discussed in this chapter are shown in Figure 1.