Additional clinical trials have evaluated alternative TSPO-targeted PET ligands, including 18F-FEDAA1106 (NCT01031199), 18F-GEH120714 (NCT01738347), and 11C-PK11195 (NCT02207075, NCT04239820), with a focus on safety, biodistribution, and signal quantification in both relapsing-remitting and progressive MS populations (Table 1). Here, TSPO is linked to myeloid sarcoma.