Pos1372 Contrast-Enhanced Ultrasound as a Valuable Tool to Detect Minimal Inflammation in Ra Patients in Persistent Remission

Background: Remission is nowadays an attainable target for most rheumatoid arthritis (RA) patients, but there is a lack of accurate remission markers for selecting patients for treatment taper. Although ultrasound (US) proved to detect minimal disease activity even in patients classified in clinical remission, other methods, such as contrast-enhanced ultrasound (CEUS), might be more sensitive and thus candidates to act as "true" remission markers in clinical practice. Objectives: To test CEUS as a useful tool to detect minimal inflammation in RA patients in sustained clinical remission and correlate it with disease activity scores, greyscale US (GSUS), power Doppler US (PDUS), and Global OMERACT-EULAR synovitis score (GLOESS). Methods: Thirty-two RA patients in persistent (> six months) remission (Disease Activity Score (DAS28) 4v ESR or Boolean remission), 10 RA patients with active disease (moderate or high DAS28 4v ESR), and 10 age and sex-matched healthy controls were recruited and clinically evaluated (joint counts, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and patient-reported outcomes (PROs) and by US of 28 joints). GSUS, PDUS, and GLOESS total scores were calculated. The joints with higher synovitis score were selected to perform CEUS. CEUS videos were recorded in DICOM format and scored blindly using the semiquantitative International Arthritis Contrast Ultrasound Score (IACUS). CEUS quantification was performed using a dedicated software, allowing the calculation of time-intensity curves (TIC). From the TIC, the signal intensity maximum (SiMax) and minimum (SiMin) were collected, and the signal intensity ratio was calculated (SiR=SiMax/SiMin). Results: At the time of the US evaluation, of the 32 screened patients in persistent clinical remission, 24 were still in remission, 5 in low, and 3 in moderate disease activity. Remission and low disease activity were merged into one group (RL, n=29), and the moderate disease activity group that came from the persistent remission cohort (n=3) was assessed together with the moderate and high disease activity group (MH, n=13). Healthy and RL groups had similar total scores of GSUS, PDUS, and GLOESS. MH groups had higher scores of GSUS, PDUS, and GLOESS compared to healthy and RL groups, with statistically significant differences in all scores when comparing with healthy but only in PDUS when comparing with RL (Table 1). Ninety-five joints were selected for CEUS examination, 20 from healthy controls. We detected more microvascularisation with the IACUS CEUS score than with PDUS: 25 vs 5% in the healthy controls, 54 vs 15% in the RL group and 90 vs 52% in the MH group (p-value <0.001) (Table 2). The Spearman's correlation between CEUS quantification of single joints (using the SiR) and the other single joint US scores were 0.655 (moderate to strong), 0.509 (moderate), 0.289 (weak), and 0.286 (weak), respectively for IACUS CEUS, PDUS, GLOESS, and GSUS. Conclusion: For most RA patients in persistent clinical remission, conventional US may also fail to detect microvascularisation potentially related to the subclinical disease. CEUS may be a useful tool to identify in clinical practice RA patients in "true" remission. REFERENCES: NIL. Acknowledgements: Neurology Department of Hospital de Santa Maria for allowing to use the equipment and space for the ultrasound procedures. Nurse staff of Rheumatology Department of Hospital de Santa Maria and Centro de Investigação Clínica of Hospital de Santa Maria. Disclosure of Interests: Joaquim Polido-Pereira Abbvie, Lilly and Pfizer., Pharmakern, Abbvie and MSD., Manuel Silvério-António Menarini and Theramex., Nikita Khmelinskii: None declared, Marta Arese: None declared, Rui Lourenço Teixeira: None declared, Elsa Vieira-Sousa: None declared, Maria-Antonietta D'Agostino: None declared, Joao Eurico Fonseca: None declared