I-123-BMIPP, a Radiopharmaceutical for Myocardial Fatty Acid Metabolism Scintigraphy, Could Be Utilized in Bacterial Infection Imaging

In this study, we evaluated the use of 15-(4-I-123-iodophenyl)-3(R,S)-methylpentadecanoic acid (I-123-BMIPP) to visualize fatty acid metabolism in bacteria for bacterial infection imaging. We found that I-123-BMIPP, which is used for fatty acid metabolism scintigraphy in Japan, accumulated markedly in Escherichia coli EC-14 similar to F-18-FDG, which has previously been studied for bacterial imaging. To elucidate the underlying mechanism, we evaluated changes in I-123-BMIPP accumulation under low-temperature conditions and in the presence of a CD36 inhibitor. The uptake of I-123-BMIPP by EC-14 was mediated via the CD36-like fatty-acid-transporting membrane protein and accumulated by fatty acid metabolism. In model mice infected with EC-14, the biological distribution and whole-body imaging were assessed using I-123-BMIPP and F-18-FDG. The I-123-BMIPP biodistribution study showed that, 8 h after infection, the ratio of I-123-BMIPP accumulated in infected muscle to that in control muscle was 1.31 at 60 min after I-123-BMIPP injection. In whole-body imaging 1.5 h after I-123-BMIPP administration and 9.5 h after infection, infected muscle exhibited a 1.33-times higher contrast than non-infected muscle. Thus, I-123-BMIPP shows potential for visualizing fatty acid metabolism of bacteria for imaging bacterial infections.