The significance of 123I-BMIPP delayed scintigraphic imaging in cardiac patients

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

OBJECTIVE

123I-15-(p-iodophenyl)-3(R,S)-methylpentadecanoic acid ([123I]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 [123I]BMIPP and image quality of [123I]BMIPP scintigraphy. However, the relationship between the myocardial accumulation of [123I]BMIPP and the feeding condition is not entirely clear. Therefore, we determined the myocardial accumulation of [125I]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 [125I]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 [125I]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 [125I]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 [125I]BMIPP, the hepatic accumulation level was increased. The present results indicate that the fed condition may provide higher-contrast images in myocardial [123I]BMIPP scintigraphy.

Discrepancy between myocardial perfusion and fatty acid metabolism following acute myocardial infarction for evaluating the dysfunctional viable myocardium

OBJECTIVE

Following acute myocardial infarction (AMI) the area of myocardial perfusion and metabolism mismatch is designated as dysfunctional viable myocardium. (123)I-beta-methyl iodophenyl pentadecanoic acid (BMIPP) is clinically very useful for evaluating myocardial fatty acid metabolism, and (99)mTc-Tetrofosmin (TF) is a widely used tracer for myocardial perfusion. This study was designed to evaluate the degree of discrepancy between BMIPP and TF at the subacute state of AMI.

METHODS

Fifty-two patients (aged 59 ± 10 years; mean 46 years) with AMI were enrolled, and all of them underwent percutaneous coronary intervention (PCI). Patients were classified according to ST-T change and PCI timing. (123)I-beta-methyl iodophenyl pentadecanoic acid and TF cardiac scintigraphy were performed on 7 ± 3.5 days of admission using a dual headed gamma camera. Perfusion and fatty acid metabolism defect were scored on a 17 segments model.

RESULTS

The mean BMIPP defect score on early and delayed images were 16.67 ± 10.19 and 16.25 ± 10.40, respectively. The mean TF defect score was 10 ± 7.69. Defect score of BMIPP was significantly higher than that of the TF (P < 0.0001; 95% CI 4.32-7.02), and there was a strong correlation between perfusion and metabolism defect score (r = 0.89, P < 0.00001). Forty-seven (90%) patients showed mismatched defect (BMIPP > TF), and 5 (10%) patients showed matched defect (BMIPP = TF). Mismatched defect score (MMDS) was significantly higher in patients with ST-segment elevation myocardial infarction (STEMI) than that of non-ST-segment elevation myocardial infarction (NSTEMI) (P < 0.041; 95% CI 0.11-5.19).

CONCLUSION

At the subacute state of AMI, most of the patients showed perfusion-metabolism mismatch, which represents the dysfunctional viable myocardium, and patients with STEMI showed higher mismatch.

123I-BMIPP delayed scintigraphic imaging in patients with chronic heart failure

OBJECTIVE

The objective of the present study was to clarify the ability of 123I-beta-methyl-iodophenylpentadecanoic acid (123I-BMIPP) to evaluate the heart-to-mediastinum (H/M) ratio and myocardial global washout rate (WR) in patients with chronic heart failure (CHF).

METHODS

The severity of CHF was evaluated on the basis of the New York Heart Association (NYHA) classification. Twenty patients with CHF (13 with idiopathic dilated cardiomyopathy and 7 with ischemic cardiomyopathy) and 11 age-matched controls underwent myocardial radionuclide imaging. Scintigraphic images were obtained from each participant at the early (30 min following radio-isotope injection) and late (4 h) phases using 123I-BMIPP. The H/M ratio and WR were calculated from planar images. Concentrations of plasma brain natriuretic peptide (BNP) were measured prior to the scintigraphic study.

RESULTS

The 123I-BMIPP uptake of early H/M and global WR did not significantly differ among groups, but uptake of delayed H/M was significantly lower in patients with NYHA class III than in controls (control 2.47 +/- 0.39; class III 1.78 +/- 0.28, P < 0.05). The uptake of delayed H/M and global WR correlated with plasma log BNP in all participants (r = -0.38, P < 0.05; 0.43, P < 0.05, respectively).

CONCLUSIONS

These data suggest that 123I-BMIPP uptake of delayed H/M enhances the image of CHF severity. The myocardial WR of 123I-BMIPP also effectively depicted the severity of CHF.