Effects of feeding condition on the myocardial and hepatic accumulation of radioiodine-labeled BMIPP in mice

Objective I-123-15-(p-iodophenyl)-3(R,S)-methylpentadecanoic acid ([I-123]BMIPP), a fatty acid analog, is widely used for the diagnosis of cardiac diseases. Feeding condition is one of the important factors in the myocardial fatty acid uptake, which may also affect myocardial accumulation of [I-123]BMIPP and image quality of [I-123]BMIPP scintigraphy. However, the relationship between the myocardial accumulation of [I-123]BMIPP and the feeding condition is not entirely clear. Therefore, we determined the myocardial accumulation of [I-125]BMIPP in mice at various metabolic statuses induced by fasting in comparison with the hepatic accumulation. Methods Fed or fasted (6-, 12-, and 24-h fasted) mice were intravenously injected with [I-125]BMIPP (35.2-75.0 kBq, 4 nmol). Radioactivities in the heart and liver were measured at 1, 5, 10, 30, 60, and 120 min after the injection (n = 5-15/time point for each group), and then, the heart-to-liver (H/L) ratios were calculated. Results The myocardial accumulation level of [I-125]BMIPP in the fed group was almost the same as that in the 6-h-fasted group at each time point, although it was decreased by 12- and 24-h fasting. The H/L ratios of [I-125]BMIPP accumulation level were significantly decreased by fasting (1.92 +/- 0.22, 1.45 +/- 0.13, 1.12 +/- 0.13, and 0.91 +/- 0.15 at 10 min, and 3.30 +/- 0.62, 2.09 +/- 0.35, 1.79 +/- 0.34, and 1.27 +/- 0.06 at 30 min after the injection, respectively, for the fed group and the 6-, 12-, and 24-h-fasted groups;p < 0.0001), largely owing to the increase in the hepatic accumulation level in the fasting groups. Conclusion Although short-period (6 h) fasting did not affect the myocardial accumulation level of [I-125]BMIPP, the hepatic accumulation level was increased. The present results indicate that the fed condition may provide higher-contrast images in myocardial [I-123]BMIPP scintigraphy.