Ultrasonographic Evaluation of Salivary Glands for Sjogren's Syndrome: Diagnostic and Monitoring Insights
Summary
Salivary gland ultrasonography is a promising tool for the diagnosis and evaluation of disease activity and complications in Sjogren’s syndrome (SS). The scanning technique for salivary gland ultrasound examination relevant to SS is described in the article.
Abstract
Sjogren’s syndrome (SS) is a chronic autoimmune condition commonly affecting the exocrine glands, causing oral or ocular dryness and extraglandular manifestations including arthralgia, cytopenia, and lymphoma. The presence of autoantibodies against SSA/Ro, labial salivary gland biopsy, ocular staining, Schirmer’s test, or salivary flow assessment are included in the current classification criteria of SS. However, the availability and invasiveness of these procedures limit their widespread use in clinical settings. Salivary gland ultrasonography (SGUS) is a non-invasive imaging modality for the evaluation of the salivary gland parenchyma and is increasingly utilized to aid diagnosis and monitoring in SS.
This article presents the protocol of SGUS for image acquisition at the parotid and submandibular glands. The objective is to present a standardized, reproducible, and practical approach to diagnostic SGUS for SS in daily clinical settings. Major salivary glands are scanned in a stepwise approach, beginning at the angle of the mandible for the superficial lobe of the parotid gland, followed by the deep lobe below the ramus of the mandible. Submandibular areas are then scanned for the submandibular glands. The steps in obtaining salivary gland images at each anatomical site are explained in the accompanying video. The echogenicity and echotexture at the thyroid gland are taken as a reference. The homogeneity, the presence and distribution of hypoechoic areas within the glands, and the border of the salivary glands are examined. The sizes and features of intra-/peri-glandular lymph nodes are recorded. The most distinctive sonographic feature in SS is glandular heterogeneity with the presence of hypoechoic/hyperechoic areas within the glands.
In summary, while SGUS cannot diagnose SS on its own, it can supplement the current classification criteria of SS and guide the clinical decision for salivary gland biopsy to support the diagnosis of SS in patients with sicca syndrome or suspicious systemic features, combined with autoantibody testing.
Introduction
Sjogren’s syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration in exocrine glands, including the salivary and lacrimal glands. Xerostomia, keratoconjunctivitis sicca, and extraglandular manifestations, including arthralgia, cytopenia, and lymphoma, are described in patients with SS. SS can be divided into primary and secondary types, in which the latter occurs in association with other connective tissue diseases. In the 2016 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria for primary SS, anti-SSA/Ro positivity and lymphocytic infiltration in labial salivary gland biopsy contributed to the two major criteria, whereas Schirmer’s test, ocular staining score, and unstimulated salivary flow represented the rest of the minor criteria1. The criteria are summarized in Table 1. Labial biopsy is an invasive procedure with potential complications, including sampling error, sensory loss, and hematoma formation2. Ocular staining tests and salivary flow assessment require specialized settings and might not be widely available.
Salivary gland ultrasonography (SGUS) is a non-invasive imaging modality that provides a detailed examination of the superficial salivary gland structure, which is commonly affected in patients with SS. Lymphocytic infiltration and inflammation in the salivary glands often lead to fatty infiltration, fibrosis, and loss of parenchyma, resulting in parenchymal inhomogeneity detected in SGUS3. The Outcome Measures in Rheumatology Clinical Trials (OMERACT) working group derived an ultrasound scoring system from grades 0 to 3 to semi-quantify inhomogeneity and the presence of hypoechoic areas within the parotid or submandibular glands4. A cutoff of grade 2 or above in at least one gland was found to correlate with positive labial biopsies, sialometry, and positive autoantibodies5. It demonstrated excellent specificity and good sensitivity in fulfilling the 2016 ACR/EULAR classification criteria for primary SS when given similar weight as the minor criteria. This protocol presents a standardized and practical approach for diagnosing SGUS in SS in clinical settings.
Protocol
Representative Results
Discussion
Ultrasonography of the major salivary glands is a non-invasive and accessible imaging modality with high spatial resolution. The procedure of performing SGUS at the major salivary glands for patients with suspected SS is described in this article to facilitate reproducible and standardized examination. Parotid and submandibular glands are superficially located, which permits detailed examination by high-frequency ultrasound. SGUS is useful in evaluating various clinical conditions, including SS, sialadenitis, sialolithia…
Disclosures
The authors have nothing to disclose.
Acknowledgements
This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Materials
| Examination couch | / | Quantity: 1 | |
| High frequency linear transducer of at least 10 MHz | SL2325 18-6 MHz linear transducer | Quantity: 1 | |
| Ultrasound console | Esaote my lab seven | Quantity: 1 | |
| Ultrasound gel | / | Quantity: 1 |
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