PET imaging in multiple sclerosis

Positron emission tomography (PET) is a non-invasive technique for quantitative imaging of biochemical and physiological processes in animals and humans. PET uses probes labeled with a radioactive isotope, called PET tracers, which can bind to or be converted by a specific biological target and thus can be applied to detect and monitor different aspects of diseases. The number of applications of PET imaging in multiple sclerosis is still limited. Clinical studies using PET are basically focused on monitoring changes in glucose metabolism and the presence of activated microglia/macrophages in sclerotic lesions. In preclinical studies, PET imaging of targets for other processes, like demyelination and remyelination, has been investigated and may soon be translated to clinical applications. Moreover, more PET tracers that could be relevant for MS are available now, but have not been studied in this context yet. In this review, we summarize the PET imaging studies performed in multiple sclerosis up to now. In addition, we will identify potential applications of PET imaging of processes or targets that are of interest to MS research, but have yet remained largely unexplored.