SP0050 Opportunities and challenges of imaging in primary sjÖgren’s
Authors: S. Jousse-Joulin
Journal: Annals of the Rheumatic Diseases (2018)

<h3></h3> Sjogren's syndrome (SS) is a chronic autoimmune inflammatory disorder of exocrine glands. Its diagnosis relies solely on a combination of clinical and laboratory findings. However, recent developments have shown that imaging techniques may have additional value in detecting salivary glands abnormalities in pSS. In general, sialography is considered to be the most reliable of the imaging methods. Salivary gland scintigraphy is very sensitive and especially useful in early stages of the disease. Nevertheless, both imaging techniques are used by only minority of rheumatologists for diagnosis of pSS because of the invasive character of sialography and the low specificity of scintigraphy. MRI has shown a good sensitivity and specificity to detect structural abnormalities in pSS but few centres have access to the specific know-how. A recent development is the increased interest in ultrasonography (US) as a tool to assess major salivary glands. Ultrasonography of the salivary glands (SGUS) appears to be an inexpensive commonly available noninvasive technique that does not cause complications and inconvenience to the patient, although the data are somewhat conflicting. Although, the recent but preliminary American classification criteria for Sjögren syndrome do not include salivary gland such imaging technique<sup>1</sup> this procedure has clearly demonstrated high impact on classification of Sjögren patients<sup>2–5</sup> and demonstrated good diagnostic properties.<sup>5</sup> A systematic literature review<sup>6</sup> has shown a paucity of data regarding the metric properties of ultrasound, making interpretation and comparison of studies difficult. In particular, there are limited data describing a standardised scanning method and standardised definitions of US gland pathologies. Even if we obtained truth validity, discrimination validity (reliability) is not yet validated. Therefore, although SG-US is an upcoming modality in rheumatology, it is not yet ready to make diagnostic or therapeutic decisions regarding salivary glands in daily routine practice. It should still considered to be a research tool, until we are able to demonstrate acceptable intra- and interobserver reliabilities. Preliminary work addressing these issues has been done so far by the USpSS study group consisting of both clinicians and ultrasonographers.<sup>6, 7</sup> More recently, a SG-US OMERACT task force group composed of international clinicians and ultrasonographers was created with the aim of developing a standardised scanning method using standardised definitions of gland pathology. A consensual Delphi process about definitions and scoring using B mode modality of SG-US was used and the intra and inter reliabilities between 18 sonographers showed good to excellent reliabilities (Light's kappa=0.81, Light's kappa=0.71 respectively) (article in preparation). Currently, there is an unmet need concerning the use of SGUS in the monitoring of patients. Even if it seems that structural damage are stable over time.<sup>8</sup> Another possible way to study SG in the disease course is to use Doppler. Doppler waveform analysis was found useful for detecting blood flow abnormalities in SG of patients with pSS compared to controls.<sup>9</sup> Given the importance of parotid and submandibular glands involvement in pSS, we believe that the vascularisation and B mode sonography should be evaluated routinely. A new US technique measuring the elasticity of SG parenchyma using elastography has recently emerged and could be implemented in the evaluation of SGUS pSS patients.<sup>10–12</sup> Some authors showed that stiffness of SG parenchyma was increased compared to healthy controls and suggested to adjunct this procedure to gray-scale ultrasonography for the clinical diagnosis of pSS. The last important challenge is to know if imaging techniques are capable to replace minor salivary glands biopsy. A recent study<sup>13</sup> has shown good agreement between SGUS and parotid gland and moderate with labial glands. In conclusion, US has nearly completed the 3 pillars of the OMERACT process (truth validity, discrimination validity and feasibility). The use of different imaging technique and particularly ultrasonography should be educated and it is now of importance to train the rheumatologists to this technique as proposed by The US EULAR courses. <h3>References</h3> [1] Shiboski CH, et al. <i>ARD</i> 2017. [2] De Vita S, et al. Clin Exp Rheumatol1992. [3] Goules AV, et al. Nat Rev Rheumatol2014. [4] Obinata K, et al. 2010. [5] Wernicke D, et al. J Rheumatol2008. [6] Jousse-Joulin S, et al. 2016. [7] Vitali C, et al. Arthritis Rheum2013. [8] Gazeau P, et al. Joint Bone Spine2018. [9] Jousse-Joulin S, et al. Biologics2007. [10] Hofauer B, et al. <i>Ultrasound Med Biol</i> 2016. [11] Zhang S, et al. <i>Ultrasound Med Biol</i> 2016. [12] Dejaco C, et al. <i>Ultrasound Med Biol</i> 2014. [13] Mossel E, et al. <i>ARD</i>2017. <h3>Disclosure of Interest</h3> None declared