POS1370 DOES WHOLE-BODY MRI AND ULTRASOUND SHOW A COMPARABLE INFLAMMATORY DISEASE BURDEN IN PATIENTS WITH RHEUMATOID ARTHRITIS AND PSORIATIC ARTHRITIS?
Authors: M. B. Axelsen, A. E. F. Hadsbjerg, L. Terslev, U. Møller Døhn, I. Eshed, D. Glinatsi, J. Møllenbach Møller, R. P. Poggenborg, M. Østergaard
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Whole-body magnetic resonance imaging MRI (WBMRI) allows assessment of multiple joints in patients with inflammatory arthritis. The use of WBMRI in clinical studies is growing and a scoring system for WBMRI peripheral arthritis and enthesitis has been developed and validated by OMERACT (MRI-WIPE)[1]. Ultrasound (US) is a widely used and validated method for examining both joints and entheses in patients with inflammatory arthritis [2]. <h3>Objectives:</h3> To describe the degree of inflammation found by WBMRI and US in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and healthy controls (HC). Further, to examine the discriminatory ability of WBMRI and US between patients with arthritis and HC. <h3>Methods:</h3> From a WBMRI cohort study of RA and PsA patients with clinically active disease, defined as ≥2 clinically swollen joints and ≥3 clinically tender joints and HC [3], 15 participants were included in a supplementary US protocol. The WBMRI protocol included T1-weighted and STIR coronal sequences of shoulders, hips, hands and ankles/feet, and sagittal sequences of knees, ankles, and feet. In total, 67 of 83 peripheral joints (distal interphalangeal joints (DIP) of hands and feet and proximal interphalangeal joints (PIP) of feet were excluded) and 33 peripheral entheses were scored using the OMERACT WBMRI scoring system. Inflammation was scored as synovitis and bone marrow edema (BME) for joints, and as BME and soft tissue inflammation (STI) for entheses [1]. US was performed in longitudinal plane of the glenohumeral, acromioclavicular, sternoclavicular, hip, wrist, MCP, PIP, knee, ankle, and metatarsophalangeal joints (MTPs). In total, 46 joints and 20 peripheral entheses were scored according to OMERACT US scoring system [2] for grey scale (GS) and colour Doppler (CD). Joints were scored 0-3 for WBMRI synovitis and BME scores, and US GS synovial hypertrophy. Each score was dichotomized as present/absent, with scores &gt;0 regarded as present. US CD was scored as present/absent with CD&gt;0 as sign of inflammation. Enthesitis was scored for presence/absence of WBMRI STI and BME, and for US presence of hypoechogenicity or thickened enthesis +/- CD. The sum of inflammation (0-2) for each of the two modalities was compared using descriptive statistics. <h3>Results:</h3> The median (min-max) age was 47 (39-53)/52(35-56)/36.5(33-40) for PsA/RA/HC. Average disease duration was 10 (0-24)/6 (3-22) years (min-max) for PsA/RA. Inflammation scores for joints and entheses are presented in Table 1. For patients, inflammation was most frequent in MTPs and wrists (67-100%); WBMRI also demonstrated frequent inflammation in ankles (50%). In RA patients, inflammation was frequent in MCPs and in PsA patients also in shoulders and SCJs, see Table 1. In Figure 1, inflammation scores for patients for WBMRI and US are presented. On patient level, the median (min-max) of total joint inflammation for RA/PsA were 11.5 (2-38)/11(7-29) for WBMRI and 11(4-38)/12(5-20) for US. The total inflammation joint scores for HC were 4(2-9)/0.5(0-8) for WBMRI/US; difference between HC and arthritis cohort was p=0.020/p=0.006 for WB-MRI/US, See Table 1. For enthesitis, the median (min-max) WBMRI enthesitis sum score was 1 (0-4)/ 3 (0-7) for HC/patients, p=0.23. The median (min-max) US enthesitis sum score for HC/patients was 0 (0-0)/ 2 (1-4), p=&lt;0.001. <h3>Conclusion:</h3> Despite clinically swollen and tender joints, the inflammatory burden was low and comparable as assessed by both WBMRI and US of peripheral joints and entheses. Inflammation was detected in some controls, but significantly less than in patients with arthritis. <h3>REFERENCES:</h3> [1] Krabbe, S et al, J Rheum, 2019;46:1215-21 [2] D'Agostino, M-A et al. RMD Open 2017;3:e000428 [3] Poulsen, AEF et al, J Rheum, 2021;48:198-206 <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>