TSPO and relapsing-remitting multiple sclerosis: Recently, it has been immunohistochemically demonstrated that lesions with a hyperintense rim on quantitative susceptibility mapping at MRI imaging from both secondary progressive MS (SPMS) and relapse-remitting MS (RRMS) patients demonstrate a higher level of innate immune activation as measured on TSPO-PET imaging (Kaunzner et al. 2019).