Value of 99mTc-IgG scintigraphy in the prediction of joint destruction in patients with rheumatoid arthritis of recent onset

Molecular imaging of rheumatoid arthritis: emerging markers, tools, and techniques

Early diagnosis and effective monitoring of rheumatoid arthritis (RA) are important for a positive outcome. Instant treatment often results in faster reduction of inflammation and, as a consequence, less structural damage. Anatomical imaging techniques have been in use for a long time, facilitating diagnosis and monitoring of RA. However, mere imaging of anatomical structures provides little information on the processes preceding changes in synovial tissue, cartilage, and bone. Molecular imaging might facilitate more effective diagnosis and monitoring in addition to providing new information on the disease pathogenesis. A limiting factor in the development of new molecular imaging techniques is the availability of suitable probes. Here, we review which cells and molecules can be targeted in the RA joint and discuss the advances that have been made in imaging of arthritis with a focus on such molecular targets as folate receptor, F4/80, macrophage mannose receptor, E-selectin, intercellular adhesion molecule-1, phosphatidylserine, and matrix metalloproteinases. In addition, we discuss a new tool that is being introduced in the field, namely the use of nanobodies as tracers. Finally, we describe additional molecules displaying specific features in joint inflammation and propose these as potential new molecular imaging targets, more specifically receptor activator of nuclear factor κB and its ligand, chemokine receptors, vascular cell adhesion molecule-1, αVβ₃ integrin, P2X7 receptor, suppression of tumorigenicity 2, dendritic cell-specific transmembrane protein, and osteoclast-stimulatory transmembrane protein.

Technetium-99m labelled human immunoglobulin scintigraphy predicts rheumatoid arthritis in patients with arthralgia

The ability of 99mTc-IgG scintigraphy to predict the development of rheumatoid arthritis (RA) in 47 patients with arthralgia was investigated. 99mTc-IgG scintigraphy and the serum test for rheumatoid factor (RF), measured at the beginning of a year long study, were compared for their ability to predict RA. During the study 8 patients developed RA. The specificity and positive predictive values of RF in predicting RA were 79% and 50% respectively; and for 99mTc-IgG scintigraphy 97% and 88%. The sensitivity and negative predictive values of RF were 100% and of 99mTc-IgG-scintigraphy 88% and 97% respectively. In conclusion, 99mTc-IgG scintigraphy has additional value to RF with respect to the prediction of the development of RA in patients with arthralgia.