Ab0308 quantification of sarcopenia in patients with rheumatoid arthritis by measuring the cross-sectional area of the thigh muscles with magnetic resonance imaging

Background Sarcopenia is a prevalent condition in patients suffering from rheumatoid arthritis (RA), estimated to affect 31% of them. Magnetic resonance imaging (MRI) allows the measurement of cross-sectional area (CSA) and volume of a muscle and the visualization of its morphological features and their distribution. Quality deterioration of the muscle, characterised by the presence of adipose tissue (defined as myosteatosis) and of fibrous connective tissue (defined as myofibrosis), is best diagnosed with MRI. Objectives To determine the utility of CSA measurements on MRI, at the level of the thigh muscles, to estimate muscle mass in discriminating RA patients with sarcopenia from those without. Methods Consecutive female RA patients were enrolled for this cross-sectional study. Patients were assessed for disease activity, radiological damage, handgrip strength, physical performance and for the presence of sarcopenia, identified in accordance with the EWGSOP2 criteria. A 1.5T MRI machine was used to scan the thigh muscles. A dimensional region growth algorithm (HorosTM) was used to semiautomatically segment the muscles cross-sectional areas (CSAs, in cm2) on MR images located 25 cm above the knee joint (MRI-CSA-25) (Figure 1). The MRI-CSA-25 was obtained by summing the areas of the individual muscles. MRI-CSA-25 was correlated (Pearson’s r) with the other variables, and its optimal cut-off point (Youden index) for sarcopenia diagnosis was identified in relation to the EWGSOP2 criteria. Results 32 RA female patients were studied, 34.4% diagnosed as sarcopenic. The mean MRI-CSA-25 was 151.00 cm2 for patient with sarcopenia, 275.57 cm2 for patient without sarcopenia (p <0.001). MRI-CSA-25 correlated significantly with measures of physical performance, and disease activity, but not with radiological damage or age. The MRI-CSA-25 optimal cut-off point in discriminating sarcopenic patients was identified at 182 cm2 (AUC-ROC = 0.894). Conclusion MRI-CSA-25 can differentiate sarcopenic versus non-sarcopenic RA patients, representing an imaging biomarker of this condition. References [1]Salaffi F et al. Clin Rev Allergy Immunol. https://doi.org/doi: 10.1007/s12016-022-08943-z. [2]Salaffi F et al. Radiol Med 2022; 127:1277-1291. https://doi.org/10.1007/s11547-022-01560-y. Acknowledgements: NIL. Disclosure of Interests None Declared.