In MS, enhanced detection of TSPO in PET imaging studies is correlated with disease severity and clinical disability, indicating that microglial activation/neuroinflammation can be used as a general biomarker of MS disease progression (Banati et al., 2000; Politis et al., 2012a; Rissanen et al., 2014; Sucksdorff et al., 2020). Here, TSPO is linked to myeloid sarcoma.