TSPO and tropical spastic paraparesis: Advanced imaging studies support the presence of brain inflammation in HTLV-1.11C-PBR28, a PET tracer that binds to translocator protein (TSPO) on microglia and is used as a marker of neuroinflammation, showed increased cerebral, thalamic, and brainstem TPSO binding in patients with HAM with severe disease compared with those with milder disease.32