To investigate the feasibility of ⁹⁹Tc^m-hydrazinonicotinamide-(poly-(ethylene glycol))₄-E[(poly-(ethylene glycol))4-c((Arg-Gly-Asp)fK)]₂ (3PRGD₂) in the early diagnosis of rheumatoid arthritis (RA).

Sixty female Wistar rats were divided into control group (n=10; injected with saline of 0.3 ml/piece) and collagen-induced arthritis (CIA) group (n=50; injected with type Ⅱ collagen emulsion of 0.3 ml/piece). Rats in 2 groups were subjected to ⁹⁹Tc^m-3PRGD₂ planar imaging before modeling, 25 and 45 d after modeling. The changes of the target/non-target ratio (T/NT) of the lesion joint and mediastinum before and after modeling were measured and analyzed in CIA rats, and compared with rats in control group. Pathological examination was conducted. Repeated measures analysis of variance and independent-sample t test were used to analyze the data.

Thirty-two rats in CIA group were successfully established, and obvious synovitis and synovial thickening, neovascularization were observed in the images. The T/NT of diseased joints in CIA group before modeling, 25 and 45 d after modeling were 0.158±0.023, 0.402±0.144, and 0.705±0.163 (F=286.924, P<0.01). The T/NT of diseased joints at 25 and 45 d after modeling were significantly different from those of control group (0.160±0.028 and 0.158±0.032;t values: -10.484 and -20.917, both P<0.01). Immunohistochemistry results showed positive expressions of vascular endothelial growth factor, α_vβ₃ and tumor necrosis factor-α in the synovial tissue in of diseased joints in rats of CIA group.

⁹⁹Tc^m-3PRGD₂ has high sensitivity for joint synovial neovascularization in rat rheumatoid arthritis models and is expected to be used for early diagnosis of RA.

Arthritis, rheumatoid; Neovascularization, pathologic; Radionuclide imaging; Arginine-glycine-aspartic acid; Rats