The study aimed to evaluate the use of positron emission tomography/computed tomography (PET/CT) with 68Ga-PRGD2 as the tracer for imaging of synovial angiogenesis in patients with rheumatoid arthritis (RA).Methods
Twenty untreated active patients with RA underwent 68Ga-PRGD2 PET/CT and 18F-FDG PET/CT before treatment; two patients with osteoarthritis served as controls. Among the 20 patients with RA, 12 repeated the evaluations after 3-month treatment. The image findings were correlated with core variables of disease activity, including the clinical disease activity index (cDAI).Results
Our findings demonstrated that 68Ga-PRGD2 specifically accumulated in the synovia with active inflammation rich in neovasculature with high-level αvβ3-integrin expression, but not in the 18F-FDG-avid inflammatory lymph nodes. In patients with intense 18F-FDG uptake in muscles caused by arthritic pain, we observed that 68Ga-PRGD2 PET/CT was better able to evaluate disease severity than 18F-FDG PET/CT. Both 68Ga-PRGD2 accumulation and 18F-FDG uptake changed in response to therapeutic intervention, whereas the changes of 68Ga-PRGD2, not 18F-FDG, significantly correlated with clinical measures of changes in the form of cDAI.Conclusions
This is the first integrin imaging study conducted in patients with RA that preliminarily indicates the effectiveness of the novel method for evaluating synovial angiogenesis.Clinical trial registration
This study has been registered online at NIH ClinicalTrial.gov (NCT01940926).