Pilot study on 18 F-FDG PET/CT for detection of inflammatory changes in blood-induced knee arthropathy in a rabbit model.

RATIONALE: 18 F-FDG-PET/CT has a potential role in the early detection of haemophilic arthritis, at a time when treatment may still avoid further joint degeneration. The purposes of this pilot study were to determine the ability of 18 F-FDG-PET/CT to detect inflammatory changes associated with blood-induced arthropathy in knees of a rabbit model. METHODS: Ten juvenile rabbits were imaged at baseline and weeks 5 and 17 post intraarticular autologous blood injections (ABI). Five rabbits in group 1 (G1) had ABI into the same knee joint every 2 weeks (total, eight injections). Five rabbits in group 2 (G2) had only two injections into the same knee, at weeks 5 and 17. Images were assessed visually and semi-quantitatively by measuring maximal standardized uptake values (SUVmax) and standardized uptake ratio (SUR = SUVmax in affected knee/SUVmax in non-affected knee). RESULTS: More rabbits in G1 than G2 presented with positive chronic inflammatory synovial scores at week 17. Mean iron staining scores in injected knees were greater for G1 than for G2 (P = 0.049). No increased uptake was identified in the injected knees in any of the rabbits at baseline or at week 5. At week 17, all G1 rabbits demonstrated increased uptake in their affected knees with higher mean SUVmax (1.5) than normal knees (1.0) (P < 0.02). None of the G2 rabbits showed asymmetric increased uptake. The SUR of G1 was higher at week 17 compared to baseline (P < 0.01) and week 5 (P < 0.01). The SUR at week 17 was higher for G1 than for G2 (1.13) rabbits (P < 0.01). CONCLUSION: 18 F-FDG-PET is able to detect the inflammatory changes associated with haemophilic arthropathy in this experimental model.