New Imaging Tracers for the Infected Diabetic Foot (Nuclear and Optical Imaging)

Diabetic Foot Infections (DFIs) are associated with increased morbidity, an economic burden on patients, their families and healthcare systems and increased mortality. Early diagnosis with prompt, appropriate and adequate treatment of the infected diabetic foot is crucial. The determination of DFIs, however, may be quite perplexing and invasive. Imaging is useful in the evaluation of certain cases of DFIs, especially in suspected instances with no overt clinical features, or in the diagnosis of osteomyelitis. Nuclear medicine imaging is currently used in the evaluation of DFIs; however, like all the imaging techniques now available, it has its limitations. Several radiopharmaceuticals presently available play useful roles in the management of DFIs, while new ones are being evaluated. Optical imaging techniques have recently demonstrated promising results in the evaluation of many infections including DFIs. Using the same molecule, a tracer can be labeled with a radioisotope or an optical imaging dye. This enables infections to be evaluated both pre- and intra-operatively when surgery is required in their management. In some cases, tracers have been simultaneously labeled with both a radioisotope and an optical imaging dye to produce a hybrid tracer. These new tracers potentially provide powerful and new opportunities in the management of DFIs. In this review, we briefly examine tracers that have been used in the evaluation of the infected diabetic foot. We then explore the potential of new imaging tracers currently under development for infection that may be useful in the management of DFIs.