beta-Methyl-p-(123I)-iodophenyl pentadecanoic acid single-photon emission computed tomography in cardiomyopathy

Abstract

beta-Methyl-p-(123I)-iodophenyl pentadecanoic acid (BMIPP) is one of the branched-chain free fatty acids, which has suitable characteristics for myocardial SPECT because of higher uptake and longer retention in the myocardium. Recent advances of BMIPP myocardial SPECT for evaluating cardiomyopathy were reviewed. BMIPP defects were observed in 80% patients with hypertrophic cardiomyopathy (HCM). Moreover, BMIPP uptake was reduced at sites that corresponded with hypertrophic areas, where thallium uptake was increased. The correlations between severity score and septal wall thickness and LV function were better with BMIPP SPECT, suggesting that BMIPP is more suitable for the assessment of myocardial integrity in HCM. The dissociation between BMIPP and thallium defects was not observed frequently in dilated cardiomyopathy (DCM). We carried out BMIPP myocardial SPECT to evaluate the therapeutic effects of co-enzyme Q10 on DCM patients. Hearts to the mediastinum ratio and BMIPP defect scores were significantly decreased after co-enzyme Q10 treatment. BMIPP myocardial SPECT was confirmed to be sensitive in evaluating the therapeutic effect for the perspective of metabolic SPECT imaging. Recently, a lack of myocardial uptake of BMIPP has been found in a small subset of patients (0.3%-1.2%). Cardiac radionuclide imaging using BMIPP and 18F-FDG were performed on patients with type I CD36 deficiency. The percent dose uptake of 18F-FDG was significantly higher than in normal controls. CD functions as a major myocardial long-chain fatty acid transporter and its absence may lead to a compensatory upregulation of myocardial glucose uptake. An increased frequency of CD36 deficiency was demonstrated in cardiomyopathy. Therefore, fatty acid transport proteins and their related gene defects in relation to BMIPP uptake may become an important issue in the future.