A comparison between terminally radioiodinated hexadecenoic acid (125I-HA) and heptadecanoic acid (131I-H0A) in the dog heart

The regional myocardial distribution of ¹²⁵I-16-iodo-9-hexadecenoic acid (¹²⁵I-HA) and ¹³¹I-17-iodo-heptadecanoic acid (¹³¹I-H⁰A) was determined in one normal dog and in five dogs within 5 min after coronary artery occlusion. The total myocardial uptake of ¹²⁵I-H A was about 40% lower than that of ¹³¹I-H⁰A. The ratio ¹²⁵I:¹³¹I in the normally perfused parts of the myocardium was 0.38–0.81, but the ischemic tissue showed a higher ¹²⁵I:¹³¹I-¹³¹I ratio (0.87–1.03), due to lower accumulation of ¹³¹I-H⁰A in ischemic myocardium. We conclude that both radioiodinated fatty acids are reliable indicators of myocardial perfusion and that iodo-heptadecanoic acid, when labeled with ¹²³I, may be preferred to iodo-hexadecenoic acid as the labeled fatty acid for cardiac imaging agent in clinical practice.