Quantification of 18F-labelled fluorodeoxyglucose (18F-FDG) joint uptake in progressive arthritis. Inflammatory metabolic effects of arthritis differing from 18F-FDG accumulation in normal joint tissue are seen above an arbitrary baseline of 2% of injected dose per gram. (a) Onset of clinical arthritis at day 9 resulted in a significant increase of 18F-FDG signalling in the fore limb carpal joints with a maximum at day 13 and a subsequent decreased 18F-FDG uptake in parallel to declining inflammation at days 21 and 35 (n = 6 to 9 per time point). (b) Hind limb arthritis progression reflected by 18F-FDG signalling in the tarsal joint, coinciding with carpal joint signalling. % ID/g, percentage of injected dose per gram. *P < 0.05; **P < 0.01; ***P < 0.001.