Advances in imaging techniques for Sjogren's disease.

Imaging of salivary glands (SG), particularly Salivary Glands Ultrasonography (SGUS) is increasingly used in patients with suspected Sjogren's disease (SD). SGUS is the first-line imaging modality. Numerous studies have highlighted this non-invasive, non-irradiating, and low-cost imaging modality. The OMERACT group has established a classification of SG structural damage based on B-mode findings, ranging from grade 0 (normal) to 3 (severe structural damage). SGUS abnormalities (≥ grade 2) have been reported in approximately 63 % of patients with SD. More recently, Hocevar et al. described a Doppler-based classification assessing SG parenchymal vascularization, graded from 0 (normal) to 3 (Doppler signals occupying the entire glandular surface) and could be used as a marker of disease activity and as a biomarker of response to therapy. Moreover, SGUS can be useful for looking for complications such as lymphoma. New ultrasound techniques are currently being developed, including elastography for assessing tissue stiffness, analysis of microvascularization using contrast-enhanced ultrasound with microbubbles, and analysis of minor salivary glands using the ultra-high frequency probe. The combination of several US modalities enhances both sensitivity and specificity of the technique, allowing for the development of a comprehensive multimodal imaging approach. Other imaging techniques can be performed for SD, such as MRI of the parotid glands, allowing analysis of the glandular parenchyma ("salt and pepper" appearance), and certain sequences (DWI-MR) should be performed when lymphoma or other tumors are suspected. 18-FDG PET-CT may be useful to detect systemic manifestations or complications in SD and new PET tracers are currently being developed.