Figure 6: TSPO PET imaging in neuroinflammation. (A) 11C-PK11195 PET in patients with Alzheimer’s disease shows increased uptake suggestive of microglia activation in the entorhinal, temporoparietal and cingulate cortex. (B) 11C-PK11195 PET in a patient with acute ischemic stroke. Coregistered T1-weighted MRI and PET demonstrated 11C-PK11195 enhancement surrounding the infarct seen on MRI on day 5, while considerable overlap between MRI and PET was found on day 13. (C) Chronic microglia activation following TBI as evaluated by 11C-PK11195 PET, where increased uptake in the thalami of all TBI subjects is seen compared to control individuals. (D) In a patient with MS, focally increased uptake of the TSPO PET agent 11C-PBR28 is seen in gadolinium enhancing and FLAIR hyperintense MRI lesions (arrows). (Modified from Cagnin et al. [90] Gerhard et al. [93], Ramlackhansingh et al. [92], and Oh et al. [124] with permission.)