[15] Combined PET/CT images confirmed the localization of the tracer in thickened synovia in knee joints.[15] Therefore, pre-treatment with rituximab is necessary for saturating the peripheral binding sites, and visualization of the CD20-antigen expression could provide a tool to localize sites of inflammation and could be of additive value in the treatment follow-up of RA patients. In one study, Minamimoto et al.[52] examined an RA patient who complained of cervical lymphadenopathy at 66 months after initiation of methotrexate (MTX) treatment for RA. PET/CT imaging showed an FDG-avid lesion at bilateral tonsils, bilateral supraclavicular fossa, bilateral axillary nodes and left inguinal

region. Diffuse large B cell lymphoma (DLBCL) was proven from the biopsy tissue of the FDG-avid lesion at the right supraclavicular fossa. In another patient with a 10-year history of RA, splenomegaly, liver tumor and left renal tumor were identified on Ganetespib CT examination. After a week’s withdrawal of MTX, these lesions shrank, Roxadustat but rapid regrowth occurred when MTX therapy was restarted. PET/CT imaging showed FDG-avid foci at the right inguinal region, para-aortic region, bilateral adrenal glands and liver.[52] These findings showed the usage of FDG PET/CT for diagnosis and follow-up of patients with MTX-related malignancies.

The mean of aortic maximum 18F-FDG target-to-background ratios (TBRmax) in the whole aorta was significantly higher in RA patients in comparison with cardiovascular disease (CVD) patients.[44] Similarly, there was a marked rightward shift in the distribution of TBRmax at baseline in RA patients compared with CVD patients, and RA patients had a higher proportion of hot slices within the aorta than were found in CVD patients.[44] However, find more after anti-TNF therapy (adalimumab, etanercept), PET/CT images showed a strong reduction in mean aortic TBRmax and reduced proportion of hot slices.[44] Similarly, 18F-FDG PET/CT imaging on RA patients showed distinct areas

of extra-articular soft tissue FDG uptake, such as axillary lymph nodes, epitrochlear lymph node, cervical lymph nodes, inguinal nodes, thyroid gland and subcutaneous (possibly rheumatoid) nodules.[24, 42, 43, 53-57] In addition, PET/CT imaging can find RA-complicated diseases such as interstitial pneumonia,[58] multiple extra-articular synovial cysts,[59] rheumatoid lung disease[60, 61] and atlanto-axial osteoarthritis.[62] Collectively, these data suggest that FDG PET/CT is not only able to find RA-complicated tumors, but also has the potential to detect RA-complicated inflammatory diseases. Positron emission tomography/computed tomography has become a valuable ancillary tool for evaluating RA. This technique can visualize the degree of disease activity or ‘burden of inflammation’. It may be helpful for the assessment of the extent of RA throughout the whole body, including high-risk lesions such as those in the atlanto-axial joint.