Myocardial distribution of iodine-123-iodophenyl-9-methyl-pentadecanoic acid (9MPA) in patients with acute myocardial infarction. Comparison with regional wall motion obtained from technetium-99m-sestamibi gated SPECT

123I-iodophenyl-9-methyl-pentadecanoic acid (9MPA) is a modified long-chain (15 carbons) fatty acid with a methyl branch on its 9 carbon location. Myocardial SPECT images (two sets, 10 min each) were obtained starting 10 min (early phase) and 50 min (delay phase) after the injection of 160 MBq 123I 9MPA at rest in 10 patients with acute myocardial infarction. The segmental myocardial uptake (%uptake) and clearance (%washout) from early to delay image were calculated by the SPECT data. ECG-gated myocardial SPECT with 99mTc-sestamibi was also performed and segmental left ventricular (LV) wall motion was evaluated using QGS (quantitative gated SPECT) program. The %uptake of LV segments with hypokinetic or akinetic wall motion were significantly lower than those with normokinesis (p<0.01) for both early and delay phases. The %washout of hypokinetic segments were significantly lower than those of normokinetic regions (p<0.01), while the %washout of akinetic segments were significantly higher than those of severely hypokinetic segments (p<0.05). Thus, 123I-9MPA myocardial distribution and clearance thought to be associated with left ventricular regional wall motion. (author)