Rheumatoid arthritis: Nuclear medicine state-of-the-art imaging

Abstract

Rheumatoid arthritis (RA) is an autoimmune disease, which is associated with systemic and chronic inflammation of the joints, resulting in synovitis and pannus formation. For several decades, the assessment of RA has been limited to conventional radiography, assisting in the diagnosis and monitoring of disease. Nevertheless, conventional radiography has poor sensitivity in the detection of the inflammatory process that happens in the initial stages of RA. In the past years, new drugs that significantly decrease the progression of RA have allowed a more efficient treatment. Nuclear Medicine provides functional assessment of physiological processes and therefore has significant potential for timely diagnosis and adequate follow-up of RA. Several single photon emission computed tomography (SPECT) and positron emission tomography (PET) radiopharmaceuticals have been developed and applied in this field. The use of hybrid imaging, which permits computed tomography (CT) and nuclear medicine data to be acquired and fused, has increased even more the diagnostic accuracy of Nuclear Medicine by providing anatomical localization in SPECT/CT and PET/CT studies. More recently, fusion of PET with magnetic resonance imaging (PET/MRI) was introduced in some centers and demonstrated great potential. In this article, we will review studies that have been published using Nuclear Medicine for RA and examine key topics in the area.

miR-375 regulates the canonical Wnt pathway through FZD8 silencing in arthritis synovial fibroblasts

“…The cause is not known, but it is quite likely that the unique physiological and anatomical features of diarthrodial joints may render those targets for RA [1,2]. The normal synovial membrane comprises an intimal lining of two or three layers of fibroblast-like and macrophage-like synoviocytes embedded in a dense extracellular matrix.…”

99Tc-MDP treatment for the therapy of rheumatoid arthritis, choroidal neovascularisation and Graves' ophthalmopathy

“…Although it can affect numerous tissues and organs, it primarily involves flexible joints (6) resulting in synovitis, pannus formation (7) and massive bone destruction with consequent inflammation, pain and disability (8), associated with higher mortality as compared to the general population (9,10 Similarly, Gong et al (13) reported that 0.01 µg/ml 99 Tc-MDP significantly inhibited RANKL-induced osteoclastogenesis with no cytotoxicity, and significantly abolished the appearance of multinucleated osteoclasts, inhibited the expression of the transcription factors c-Fos, nuclear factor of activated T cells and inflammatory factors, such as IL-6, TNF-α and IL-1β. Thus, 99 Tc-MDP has anti-osteoclastogenic activity on RANKL-induced osteoclast formation.…”

Liposomal Treatment of Experimental Arthritis Can Be Monitored Noninvasively with a Radiolabeled Anti–Fibroblast Activation Protein Antibody

“…Molecular imaging has already been proven successful in noninvasive and early response monitoring but, in most cases, is not specific for arthritis at a molecular level (11,13). Fibroblast activation protein (FAP) is a cell surface-bound, type II transmembrane glycoprotein belonging to the family of serine prolyl oligopeptidases.…”