POS1394 ACCURACY AND PERFORMANCE OF A HANDHELD ULTRASOUND DEVICE TO ASSESS ARTICULAR AND PERIARTICULAR PATHOLOGIES IN PATIENTS WITH INFLAMMATORY ARTHRITIS
Authors: G. Corte, S. Bayat, K. Tascilar, L. Valor, L. Schuster, J. Knitza, G. Schett, A. Kleyer, D. Simon
Journal: Annals of the Rheumatic Diseases (2021)

Background: Handheld ultrasound (HHUS) devices have increasingly found their way into clinical practice due to several advantages (e.g. portability, significantly lower purchase cost). However, there is no evidence to date on the accuracy and performance of HHUS in patients with inflammatory arthritis (IA). Objectives: To assess accuracy and performance of a new HHUS machine in comparison to a conventional cart-based sonographic machine in patients with IA. Methods: Consecutive IA patients of our outpatient clinic with at least one tender and swollen joint in the 66/68 joint count were enrolled. US was performed on clinically affected joints with corresponding tendons/entheses using a cart-based sonographic device (“Samsung HS40”) and a HHUS device (“Butterfly iQ”) in standard scan positions. One blinded reader scored all images for the presence of following pathologic findings: erosions, bony enlargement, synovial hyperthrophy, joint effusion, bursitis, tenosynovitis and enthesitis. In addition, synovitis was graded (B Mode and power Doppler (PD)) by the 4-level EULAR-OMERACT scale [1]. To avoid bias by the blinded reader, who otherwise would have been tempted to identify pathological findings for each examined joint, we also included 67 joints of two healthy volunteers into the evaluation. We calculated the overall concordance and the concordance by type of joint and type of pathological finding between the two devices (percentage of observation pairs in which the same rating was given by both devices). The Cohen’s kappa coefficient (κ) with 95% bootstrap confidence intervals was used to assess the agreement between the two US devices. We also measured the time required for the US examination of one joint with both devices. Results: 32 patients (20 rheumatoid arthritis, 10 psoriatic arthritis, 1 gouty arthritis, 1 systemic lupus erythematosus) were included in this study. Mean age of patients was 58.2±13.7 years, 63% were females. In total 186 joints were examined. The overall raw concordance in B-mode between the two devices was 97 %, with an overall κappa for agreement of 0.90, 95% CI (0.89, 0.94). No significant differences were found in relation to type of joint or pathological finding examined. The PD-mode of the HHUS device did not detect any PD-signal, whereas the cart-based device detected a PD-signal in 61 joints (33%). The portable device did not offer any time saving compared to the cart-based device (mean time in seconds per examined region: 47 seconds for the HHUS device versus 46.3 seconds for the cart-based device). Conclusion: The HHUS device “Butterfly iQ” has been shown to be accurate in the assessment of structural joint damage and inflammation in patients with IA, but only in B-mode. Significant improvements are still needed to reliable demonstrate blood flow detection by PD mode. References: [1]D’Agostino, M.A., et al., RMD Open, 2017. 3(1): p. e000428. Table 1. Concordance between a handheld and a conventional cart-based US device in B-mode Agreement by site N joints (%) Concordance (%) Kappa 95%CI Overall 186 97 0.90 (0.89 to 0.94) Wrist 32 (17.2) 96 0.86 (0.77 to 0.93) Finger/toe joint (MCP, PIP, DIP, MTP) 114 (61.3) 97 0.92 (0.88 to 0.95) Elbows 11 (5.9) 95 0.87 (0.75 to 0.97) Shoulder 4 (2.2) 100 1.00 (NA to NA) * Knee 20 (10.7) 98 0.96 (0.90 to 1.00) Ankle 5 (2.7) 100 1.00 (NA to NA) * Agreement by pathological finding Joint effusion 95 0.81 (0.68 to 0.92) Synovitis 94 0.87 (0.79 to 0.93) Synovitis OMERACT grade (0– 3) 90 0.84 (0.76 to 0.91) Bone enlargement 98 0.88 (0.71 to 1.00) Erosion 98 0.89 (0.77 to 0.89) Tenosynovitis 98 0.83 (0.61 to 0.96) Entheseopathy 100 1.00 (NA to NA) * Bursitis 97 0.90 (0.89 to 0.94) * unreliable kappa statistics because of small number of shoulders/ankles examined and small number of entheseopathies Figure 1. Pathological US findings in MCP joints (1, 2, 3) and wrist (4) depicted by the two different ultrasound devices B-mode erosive (arrow) and synovial (asterisk) changes could be detected by both devices (1-2), while PD changes of different grades only by the conventional US device (3-4). Acknowledgements: This study was supported by the Deutsche Forschungsgemeinschaft (DFG- FOR2886 PANDORA and the CRC1181). Additional funding was received by the Bundesministerium für Bildung und Forschung (BMBF; project METARTHROS, MASCARA), the H2020 GA 810316 - 4D-Nanoscope ERC Synergy Project, the IMI funded project RTCure, the Emerging Fields Initiative MIRACLE of the Friedrich-Alexander-Universität Erlangen-Nürnberg, the Else Kröner-Memorial Scholarship (DS, no. 2019_EKMS.27) and Innovationsfond Lehre / FAU Erlangen-Nürnberg 2019. Disclosure of Interests: None declared