Invasive fungal infections are recognized as an important cause of morbidity and mortality in the immunocompromised host. Rapid initiation of adequate antifungal treatment is often hampered by the limitations of current diagnostic methods. This review encompasses the promises and limitations of newer tracers (believed to target the infectious agents), i.e., radiolabeled
antimicrobial peptides, antifungals and
chitin-specific agents, for
fungal infection imaging by scintigraphy. In mice (99m)Tc-labeled
peptides derived from human
ubiquicidin (UBI29-41) and
lactoferrin (hLF1-11) distinguished local Candida albicans and Aspergillus fumigatus
infections from sterile inflammatory processes, but not from
bacterial infections. Clinical trials showed that (99m)Tc-UBI29-41 can distinguish
infections from inflammatory lesions with 80% specificity and 100% sensitivity. (99m)Tc-hLF1-11 was able to monitor the antifungal effects of
fluconazole on C. albicans
infections. Moreover, (99m)Tc-fluconazole proved to be an excellent tracer for C. albicans
infections as it did not accumulate in
bacterial infections and inflammatory processes. However this tracer poorly detected A. fumigatus
infections. Furthermore, (123)I-chitinase and (99m)Tc-HYNIC-CBP21 accumulated in both C. albicans and A. fumigatus
infections in mice at later time points. In conclusion, despite the recent advances in radiolabeled imaging techniques for
invasive fungal infections, the search for better tracers for
fungal infection imaging should be continued.