Studying TSPO PET has confirmed the role that inflammation plays in lesion evolution, revealing that inflammation is present since the early stages of the disease, even before lesions can be identified on MRI [51]; more specifically, activated macrophages and microglia concentrate around MS lesions and also outside lesions in the NAWM and grey matter [50,51,52,53,55]. The gene discussed is TSPO; the disease is myeloid sarcoma.