POS1270 USEFULNESS OF ULTRASOUND SHEAR WAVE ELASTOGRAPHY FOR IgG4-RELATED SIALADENITIS
Authors: K. Nishimura, A. Sahara, K. Yo, O. Iri, N. Nishimura, K. Mizukawa, K. Kadoba, H. Mukoyama, R. Saito, T. Yoshida, T. Nagamoto, D. Waki, H. Murabe, J. Saegusa
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> IgG4-related disease (IgG4RD) is a chronic and systemic disease that is characterised by multiple organ inflammation, elevated serum IgG4, and storiform fibrosis. IgG4RD often presents with organ enlargement and can affect the submandibular glands, lacrimal glands, orbits, pancreas, bile ducts, retroperitoneum, lungs, kidneys, aorta and pachymeninges [1]. One of the most commonly involved organs is the submandibular glands. However, methods for evaluating the severity and treatment response of IgG4-related sialadenitis have not been established. Ultrasound shear wave elastography (SWE) is a technique to quantify tissue elasticity using shear wave velocity (SWV), and is considered to be a useful noninvasive method for diagnosing fibrosis. Recently, SWE has been reported as a valid diagnostic method for primary Sjogren's syndrome (pSS) [2]. <h3>Objectives:</h3> The purpose of this study was to investigate whether ultrasound SWE evaluate disease activity of IgG4-related sialadenitis. <h3>Methods:</h3> We retrospectively investigated the submandibular gland sonographic features of IgG4RD patients who fulfilled the 2020 revised comprehensive diagnostic criteria for IgG4RD [3]. Submandibular gland ultrasonography was performed in Kurashiki Central Hospital from April 2016 to December 2022. We assessed sex, age, affected organs, disease duration, use of glucocorticoid and immunosuppressive agents, serum IgG/IgG4, and ultrasonographic findings. We choose patients with pSS as controls for ultrasound image. The volume of the submandibular gland was calculated using the following formula: Volume = (long diameter) x (transverse diameter) x (cranial-caudal diameter) x 0.52 [4]. Submandibular gland SWV was compared between IgG4RD and pSS patients. In addition, it was compared in IgG4RD patients with and without submandibular gland lesions. Submandibular gland SWV was compared before and after treatment among patients with IgG4-related sialadenitis. <h3>Results:</h3> Twenty-nine patients (18 males, 11 females) with IgG4RD and 35 patients (4 males, 31 females) with pSS underwent submandibular gland SWE. The median age [interquartile range (IQR)] of IgG4RD and pSS was 69 (64-77) and 67 (52.5-78), respectively. The median time (IQR) since IgG4RD diagnosis was 4 days (0-547). Of the IgG4RD patients, 4 were treated with glucocorticoid (maximum 10 mg/day of prednisolone equivalent) and 2 with immunosuppressive agents (azathioprine and methotrexate). PSS patients were all untreated. The submandibular gland was the most common organ affected in 19 patients with IgG4RD, followed by the lacrimal gland (n=8), aorta (n=7), retroperitoneum (n=7), pancreas (n=6), parotid gland (n=3), lungs (n=3), pituitary gland (n=1), bile duct (n=1), pachymeninges (n=1) and vertebra (n=1). Nineteen patients with IgG4RD showed multiple hypoechoic areas in the submandibular gland. The median SWV (IQR) of the submandibular gland was 1.88 (1.59-2.40) in the IgG4RD group and 1.59 (1.43-1.72) in the pSS group, which was significantly higher in the IgG4RD group (p &lt;0.001). The median SWV (IQR) of IgG4RD was 1.59 (1.50-1.70) in the group without sialadenitis and 2.06 (1.79-2.65) in the group with sialadenitis (p &lt; 0.05) (Figure 1A). Among patients treated with immunosuppressive therapy for IgG4RD, 7 patients were followed up for submandibular gland ultrasonography. The median observation period (IQR) was 408.5 days (81.25-630.25). Ultrasound-estimated submandibular gland volume was reduced from 2.4 cm<sup>3</sup> to 1.7 cm<sup>3</sup> and submandibular gland SWV was significantly decreased from 1.98 to 1.55 (p &lt; 0.05), respectively (Figure 1B). <h3>Conclusion:</h3> Submandibular gland SWV was significantly higher in IgG4RD than in pSS. Submandibular gland SWV was elevated in IgG4-related sialadenitis, and SWV was decreased by immunosuppressive treatment. Ultrasound SWE is a useful tool for evaluating the disease activity of IgG4-related sialadenitis. <h3>REFERENCES:</h3> [1] Perugino CA, et al. Nat Rev Rheumatol 2020;16(12):702-714. [2] Ma H, et al. Int J Rheum Dis. 2023;26(7):1314-1320. [3] Umehara H, Mod Rheumatol 2021;31(3):529-533. [4] Badea AF, et al. Med Ultrason 2013;15(3):173-9. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>