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18F-FDS (Gram(-) infection)

Tumor-targeting bacteria have been actively investigated as a new therapeutic tool for solid tumors. However, in vivo imaging of tumor-targeting bacteria has not been fully established. [18F]fluorodeoxysorbitol (FDS) positron emission tomography (PET) is known to be capable of imaging Gram-negative Enterobacteriaceae infection. We validated the use of [18F]FDS PET for visualization of the colonization and proliferation of tumor-targeting Escherichia coli (E. coli ) in mouse tumor models.

18F-FDS PET imaging of tumor-bearing mice treated with E. coli.

Quantitative assessment of tumor-colonizing bacteria and PET signals in engrafted tumors.

(A) Viable bacterial counts in harvested tumors.

(B) Correlation between SUVmax and the number of viable bacteria in tumors.

[18F]FDS PET showed the distribution of tumor-targeting E. coli, even in the deep portions of tumors, and provided semiquantitative data on bacterial location without sacrificing the mice. Therefore, [18F]FDS PET has potential as a promising in vivo imaging technique for visualizing the therapeutic process when bacterial cancer therapy (BCT) is performed with Enterobacteriaceae such as E. coli.

18F-FDS (Fungal infection)

It has been known that roughly 1,500,000 people die from invasive fungal infection every year and, as the number of patients with HIV/AIDS and those who receive chemotherapy, modern immunosuppressive therapy, and invasive medical interventions are growing, the incidence of invasive fungal infection is also constantly increasing. Radiolabeled sorbitol, 2-deoxy-2-[18F]fluorosorbitol ([18F]FDS), initially evaluated for the diagnosis of glioma in mice, has been studied for imaging pathogenic E. coli. It is intriguing that sorbitol is also used as a sole carbon source supporting high fungal growth and sporulation. In conclusion, [18F]FDS showed specific targeting and prolonged retention in A. fumigatus infection with low background activity. It suggests that this radiotracer could be used as a novel PET molecular imaging agent to obtain outstanding image quality in the diagnosis of A. fumigatus infection.