Fig. 1

¹¹C-(R)-PK11195 PET scan. Coronal ¹¹C-(R)-PK11195 PET scans of two RA patients without apparent synovitis. Enhanced uptake of the macrophage-targeting PET tracer ¹¹C-(R)-PK11195 is visible as black hotspots (arrows). Interosseus muscles and nailbeds show normal background uptake