Background/Purpose:

Patients with aggressive RA develop early structural damage. As persistent inflammation is associated with bone erosions, assessing inflammatory activity may be key in treatment decision-making to slow or prevent further damage. This study aimed to determine the impact of inflammation on US and changes in erosions on MRI in early RA.

Methods: Patients with RA (ACR criteria, treatment naïve, symptom duration <2 years) were recruited and treated as per standard of care. The 2^nd-5^th metatarsophalangeal joints (MTPJs) were imaged using US (Esaote MyLab70) at study entry, 6 weeks, 3-, 6- and 12-months follow-up. MTPJs were semi-quantitatively graded for synovial thickening (ST) and power Doppler (PD) (0-3, 3=severe inflammation). The most clinically symptomatic foot at baseline was imaged using a 1.0T peripheral MRI (GE Medical) at baseline, 12-months, and at a 24-49 months follow-up. MRI erosions were semi-quantitatively graded using the OMERACT-RAMRIS system (grade 0-10) for the metatarsal heads and phalanx bases. We characterized the number of MTPJs with low (grade <2) or high (grade ≥2) ST or PD during the majority of the first 12 months, and the number of erosions that were unchanged, improved or worsened by grade ≥1 over the follow-up.

Results: Forty-one patients were included [n=33 female, mean (SD) age=51.6 (10.3) years]. Of 32 patients with follow-up MRIs, total erosion score decreased (improved erosions) in 17 patients and increased (worsened) in 18. Ten patients had a simultaneous improvement and worsening of erosions in different MTPJs. At baseline, 12- and ≥24-months, 299, 308 and 242 metatarsal heads and phalanx bases were graded on MRI. Approximately 40% of joints had a grade ≥1 erosion at each visit, and 5-7% had grade ≥2 erosions. Of all baseline erosions, 28% improved and 27% worsened after 12-months; 40% improved and 29% worsened from baseline to post-24 months. Most changes were by grade 1, and the largest change was by grade 2. Joints with persistently low ST scores had more frequent erosion healing and fewer worsened erosions than joints with persistently high ST (Table 1). MTPJs with persistently high ST had more erosions that worsened than improved after 12 months, but approximately the same number had improved and worsened erosions after ≥24 months. Persistently high PD and erosion progression occurred very infrequently. Six patients were not treated with DMARDs or biologics throughout the study duration. Four of these patients had persistently high ST, of whom 3 had worsened total erosion scores.

Conclusion: Our findings suggested that more erosions worsened in joints with persistent severe inflammation than joints with low inflammation in early RA. The value of US inflammation for predicting erosion progression warrants further investigation, especially in populations with greater disease activity.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-role-of-inflammation-in-the-evolution-of-mri-erosions-in-the-feet-of-patients-with-early-ra/