Accumulation of 18F-labelled fluorodeoxyglucose (18F-FDG) in paws of DBA/1 mice with glucose-6-phosphate isomerase (G6PI)-induced arthritis. (a) Clinical polyarthritis is characterized by swelling and redness of paws. Enhanced glucose metabolism of inflamed tissue caused an increased uptake and subsequent enrichment of 18F-FDG in carpal and tarsal joints of arthritic mice, visualized by high-resolution positron emission tomography/computed tomography (PET/CT) imaging. Surface-rendering (SR) of data using an 8% injected dose per gram threshold allowed three-dimensional visualization of tissue with pathological increased glucose metabolism. (b) Quantification of accumulated 18F-FDG as a percentage of injected dose per gram (% ID/g) within 0 to 60 minutes after injection. 18F-FDG enrichment over time in left (L) and right (R) carpal and tarsal joints in an exemplary mouse before immunization with G6PI (black symbols) (that is, before pathological changes occurred) and increased 18F-FDG joint accumulation in the same animal at the stage of acute inflammatory G6PI-induced arthritis at day 15 after immunization (white symbols) are shown. (c) Repeated 18F-FDG PET/CT in vivo determination and quantification of disease severity in carpal (C) and tarsal (T) joints in the same mice 2 days before and 9, 15, and 22 days after arthritis induction (n = 5).