Molecular imaging of rheumatoid arthritis: emerging markers, tools, and techniques
1 KU Leuven, Laboratory of Immunobiology, Rega Institute, Minderbroedersstraat 10, 3000 Leuven, Belgium
2 Department of Development and Regeneration; Rheumatology, KU Leuven, Skeletal Biology and Engineering Research Center, University Hospital Leuven, Herestraat 49, 3000 Leuven, Belgium
3 Department of Nuclear Medicine, UZ Brussel, Laarbeeklaan 101, 1090 Jette, Brussels, Belgium
4 In Vivo Cellular and Molecular Imaging Center, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Jette, Brussels, Belgium
Arthritis Research & Therapy 2014, 16:208 doi:10.1186/ar4542Published: 15 April 2014
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.