The value of MRI for detecting subclinical joint inflammation in clinically suspect arthralgia

Abstract

In the last decade, much research has focused on the development of rheumatoid arthritis (RA) and the symptomatic phase preceding the onset of clinical arthritis. Observational studies on imaging have revealed that subclinical joint inflammation in patients with arthralgia at risk for RA precedes and predicts the onset of clinically apparent arthritis. Moreover, the results of two placebo-controlled randomised proof-of-concept trials in patients with arthralgia and MRI-detected subclinical inflammation studies will soon be available. The initial results are encouraging and suggest a beneficial effect of DMARD treatment on subclinical inflammation. Since this may increase the necessity to detect subclinical joint inflammation in persons with arthralgia that are at risk for RA, we will here review what has been learnt about subclinical inflammation in at-risk individuals by means of imaging. We will focus on MRI as this method has the best sensitivity and reproducibility. We evaluate the prognostic value of MRI-detected subclinical inflammation and assess the lessons learnt from MRIs about the tissues that are inflamed early on and are associated with the clinical phenotype in arthralgia at risk for RA, for example, subclinical tenosynovitis underlying pain and impaired hand function. Finally, because long scan times and the need for intravenous-contrast agent contribute to high costs and limited feasibility of current MRI protocols, we discuss progress that is being made in the field of MRI and that can result in a future-proof way of imaging that is useful for assessment of joint inflammation on a large scale, also in a society with social distancing due to COVID-19 restrictions.

Keywords: arthritis, rheumatoid; magnetic resonance imaging; synovitis.

Figure 1

Positive predictive values for RA development in 2 years depending on different MRI features (adapted from Matthijssen et al (2019)). Legend: 5 categories: 1: no locations with subclinical inflammation, no MCP extensor tenosynovitis, 2: 1–2 locations with subclinical inflammation, no MCP extensor tenosynovitis, 3: 3 or more locations with subclinical inflammation, no MCP extensor tenosynovitis, 4: 1–2 locations with subclinical inflammation and MCP extensor tenosynovitis, 5: 3 or more locations and MCP extensor tenosynovitis. RA, rheumatoid arthritis; MCP, metacarpophalangeal.

Figure 2

Example of synovitis and tenosynovitis in the MCP joints and flexor tendons depicted with a modified Dixon sequence and conventional sequence on a 1.5 T extremity MRI scanner of one patient. Legend: left; water-only axial reconstruction of a modified Dixon sequence. Right; axial T2 weighted image of a 1.5 T extremity MRI scanner with contrast agent. Images are made in the same patient. MCP 3 and 4 are scored for synovitis. Tenosynovitis is scored in the flexor tendons of fingers 2, 3 and 4. MCP, metacarpophalangeal.

Figure 3

Example of synovitis in the metacarpophalangeal joint in a modified Dixon MRI sequence and ultrasound image of one patient on the same day. Legend: Left; water-only axial reconstruction of a modified Dixon sequence. Synovitis is depicted in MCP 2 and 3. Right; ultrasound image of the right MCP3, scored for grayscale and PD. MCP, metacarpophalangeal; PD, power Doppler.

Figure 4

Research agenda for the implementation of MRI in patients with CSA. CSA, clinically suspect arthralgia; mDixon, modified Dixon; AI, artificial intelligence.