FDG PET for rheumatoid arthritis: basic considerations and whole‐body PET/CT

Abstract

[(18) F]Fluorodeoxyglucose (FDG) is a tracer for glucose metabolism. Its distribution is not specific to cancer cells but is also observed in inflammatory tissue, including macrophages, capillaries, and fibroblasts. Rheumatoid arthritis (RA) is a systemic, chronic inflammation of the joints resulting in synovitis. The disease is characterized by fibrovascular proliferation leading to the formation of a pannus and causing high FDG uptake. Several clinical studies of RA have demonstrated that FDG uptake in affected joints reflects the disease activity of RA, with strong correlations between uptake and various clinical parameters having been noted. Furthermore, the use of FDG PET for the sensitive detection and monitoring of the response to RA therapy has been reported. FDG PET/computed tomography (CT) enables the detailed evaluation of disease in large joints throughout the whole body, which is a unique advantage of PET/CT. FDG PET/CT can also be used to detect high-risk disease complications, such as atlanto-axial joint involvement, at an early stage. The possible contribution of FDG PET to the management of patients with RA remains to be studied in detail.

In Vivo Imaging of Cell Proliferation Enables the Detection of the Extent of Experimental Rheumatoid Arthritis by 3′-Deoxy-3′-18F-Fluorothymidine and Small-Animal PET

“…Despite the different targets of these tracers, the 18 F-FDG uptake in arthritic ankles is comparable to the 11 C-(R)-PK11195 uptake (18,39). In contrast to 11 C-(R)-PK11195, 18 F-FLT and 18 F-FDG are not specific for detecting inflammation (12,18,39). Comparative studies will show whether enhanced cell proliferation ( 18 F-FLT PET) in arthritic ankles is evident before enhanced glucose metabolism ( 18 F-FDG PET).…”

“…18 F-FLT targets cell proliferation and 18 F-FDG glucose metabolism of resident and infiltrating leukocytes, whereas 11 C-(R)-PK11195 targets peripheral benzodiazepine receptors that are mainly expressed in macrophages and monocytes and not in resident cells (12,19,38). Despite the different targets of these tracers, the 18 F-FDG uptake in arthritic ankles is comparable to the 11 C-(R)-PK11195 uptake (18,39).…”

“…to investigate the extent of RA progression (12,18,19,38,39). 18 F-FLT targets cell proliferation and 18 F-FDG glucose metabolism of resident and infiltrating leukocytes, whereas 11 C-(R)-PK11195 targets peripheral benzodiazepine receptors that are mainly expressed in macrophages and monocytes and not in resident cells (12,19,38).…”

“…Thus, early diagnosis of RA, before the onset of joint destruction, is of special importance. Noninvasive molecular imaging using dedicated, highly sensitive PET systems with high spatial resolution and with specific radiolabeled biomarkers is often better than conventional radiography, CT, MR imaging, power Doppler ultrasonography, and quantitative ultrasonography for identifying the extent of the disease (8)(9)(10)(11)(12)(13)(14).…”

Immuno-PET and Immuno-SPECT of Rheumatoid Arthritis with Radiolabeled Anti–Fibroblast Activation Protein Antibody Correlates with Severity of Arthritis

“…Radionuclide imaging in RA has been mainly focused on 18 F-FDG PET/CT imaging (25), but also radiolabeled peptides such as IL1-ra, annexin-V, and small molecules such as folate, PK11195, and matrix metalloproteinase-and E-selectin-targeting molecules have been investigated both clinically or preclinically (26). In addition, radiolabeled antibodies such as anti-CD20 (rituximab) and anti-TNFa (infliximab) have been studied.…”