Extra-articular findings with FDG-PET/CT in rheumatoid arthritis patients: more harm than benefit

Metabolic and molecular imaging in inflammatory arthritis

It is known that metabolic shifts and tissue remodelling precede the development of visible inflammation and structural organ damage in inflammatory rheumatic diseases such as the inflammatory arthritides. As such, visualising and measuring metabolic tissue activity could be useful to identify biomarkers of disease activity already in a very early phase. Recent advances in imaging have led to the development of so-called 'metabolic imaging' tools that can detect these changes in metabolism in an increasingly accurate manner and non-invasively.Nuclear imaging techniques such as 18F-D-glucose and fibroblast activation protein inhibitor-labelled positron emission tomography are increasingly used and have yielded impressing results in the visualisation (including whole-body staging) of inflammatory changes in both early and established arthritis. Furthermore, optical imaging-based bedside techniques such as multispectral optoacoustic tomography and fluorescence optical imaging are advancing our understanding of arthritis by identifying intra-articular metabolic changes that correlate with the onset of inflammation with high precision and without the need of ionising radiation.Metabolic imaging holds great potential for improving the management of patients with inflammatory arthritis by contributing to early disease interception and improving diagnostic accuracy, thereby paving the way for a more personalised approach to therapy strategies including preventive strategies. In this narrative review, we discuss state-of-the-art metabolic imaging methods used in the assessment of arthritis and inflammation, and we advocate for more extensive research endeavours to elucidate their full field of application in rheumatology.

Indications for diagnostic use of nuclear medicine in rheumatology: A mini-review

Nuclear medicine techniques allow important insights not only into oncologic, neurologic, and infectious conditions, but also for the assessment of rheumatic diseases. This review provides a brief, update on the potential role of nuclear imaging in rheumatology, especially on ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography for the diagnosis of giant cell arteritis and other large vessel arteritis according to international recommendations. Besides, the potential role of this and other nuclear imaging techniques for the rheumatologic practice are summarized. With ¹⁸F-fluoride as tracer for positron emission tomography, a new option for bone scintigraphy comes up, whereas the use of a semiquantitative sialoscintigraphy is no more supported for classification of Sjögren's syndrome according to current recommendations. Other techniques are used for different organ manifestations in systemic rheumatic diseases like for myocardial infarction and apoplectic insult.