Salivary Gland Scan Test: Purpose, Test Details & Results

Salivary gland scan tests have become invaluable in evaluating the health and function of the salivary glands, especially when symptoms or clinical findings suggest disease. Whether you’re experiencing persistent dry mouth, swelling, or are being evaluated for a tumor or autoimmune disorder, these tests can provide critical functional and anatomical information. In this article, we’ll explore why salivary gland scans are performed, what the test involves, and how the results are interpreted—helping you understand each step of the process.

Purpose of Salivary Gland Scan Test

Salivary gland scan tests are primarily used to assess the function and structure of the major salivary glands (parotid, submandibular, and sublingual glands). They play a crucial role in diagnosing a range of conditions, from autoimmune diseases like Sjögren’s syndrome to tumors and chronic infections. These scans help differentiate between various causes of gland dysfunction and guide further management.

Table 1: Key Purposes of Salivary Gland Scan Tests

Diagnostics for Autoimmune and Functional Disorders

Salivary gland scans are especially valuable in objectively assessing gland function in patients suspected of having Sjögren’s syndrome or other conditions causing dry mouth (xerostomia). Quantitative parameters, such as uptake rate and washout fraction, offer reproducible measures of how well the glands are working 2 6 9 10 11. This makes the test a cornerstone for diagnosing and monitoring autoimmune diseases affecting the salivary glands.

Tumor Evaluation

While not the first-line test for tumor detection, salivary gland scans can help differentiate between certain types of tumors. For instance, Warthin’s tumors often appear as “hot” (increased uptake), whereas metastatic or malignant tumors typically appear “cold” (reduced uptake) on scintigraphy scans 3 5 7. This functional imaging complements anatomical studies like ultrasound and CT.

Infection and Inflammation

In cases of infection or inflammation, scans can track changes in gland activity. Acute infections typically show hyperactive glands, while chronic conditions such as Sjögren’s syndrome display reduced or absent uptake 3 6 7. The scans are also useful in monitoring the response to medical therapies.

Monitoring and Follow-Up

Because these scans are non-invasive and reproducible, they are frequently used for serial assessments—tracking gland function over time and monitoring response to treatment or progression of disease 3 6 11.

Salivary Gland Scan Test Details

Undergoing a salivary gland scan is a straightforward process, but understanding the technical details can ease concerns and set expectations. Modern imaging techniques, including radionuclide scintigraphy and ultrasound, provide a comprehensive view of gland structure and function.

Table 2: Salivary Gland Scan Test Modalities

Scintigraphy: The Gold Standard for Functional Imaging

• How it works: Scintigraphy, typically using technetium-99m (Tc-99m) pertechnetate, is the most established test for salivary gland function.
• Procedure:
  • A small amount of radioactive tracer is injected into a vein.
  • Dynamic imaging captures the tracer’s uptake by the salivary glands over about 30 minutes.
  • After 15 minutes, a sialogogue (like lemon juice) is given to stimulate saliva flow, allowing assessment of glandular washout 2 3 6 7.
• Parameters Measured:
  • Uptake Rate: How quickly the gland accumulates the tracer.
  • Washout Fraction: How much tracer is expelled following stimulation, reflecting gland excretory function 2.

Ultrasound: The Structural Workhorse

• Role: Ultrasound is non-invasive and highly effective for identifying structural abnormalities, such as gland enlargement, tumors, or cysts 9 10 11 12.
• Advantages:
  • No radiation exposure.
  • Immediate bedside availability.
  • High sensitivity and specificity for conditions like Sjögren’s syndrome 9 10.
• Scoring: Semi-quantitative scoring systems are used to grade tissue homogeneity and detect hypoechoic (darker) areas consistent with disease 10 11.

SPECT/CT and PET/CT: Advanced Imaging

• SPECT/CT: Combines 3D nuclear imaging with CT for precise anatomical localization and quantification of gland function. Automated segmentation using AI is now possible, reducing analysis time and increasing reproducibility 8.
• PET/CT: Emerging techniques, such as using 68Ga-PSMA-11, offer even higher resolution and may reveal functional abnormalities missed by standard scintigraphy 4.

Safety and Patient Experience

• Minimal Risks: The radiation dose from scintigraphy is low and generally considered safe. Ultrasound involves no radiation.
• Comfort: The tests are non-invasive. Some patients may feel minor discomfort from the intravenous injection or the taste of lemon juice.
• Duration: Typical scan time is about 30–60 minutes, depending on the modality and protocol used 2 3 6 8.

Salivary Gland Scan Test Results & Follow-Up

Interpreting the results of a salivary gland scan involves integrating functional and structural findings. These results guide diagnosis, management, and monitoring of a wide range of diseases.

Table 3: Interpretation of Salivary Gland Scan Results

Understanding Functional Results

• Normal Function:
  • Normal uptake and prompt washout after stimulation indicate healthy gland function 2 6 10.
• Decreased Function:
  • Reduced uptake or poor washout is seen in chronic inflammatory conditions, such as Sjögren’s syndrome, or after radiation therapy 2 3 6 9 10.
• Increased Function:
  • Sometimes seen in acute inflammation, reflecting hyperactive glands with increased tracer accumulation 3 7.

Lesion Characterization

• “Hot” Lesions:
  • Localized increased uptake often points to Warthin’s tumors 3 5 7.
• “Cold” Lesions:
  • Areas with no or reduced uptake suggest malignancy, cysts, or abscesses. These findings may prompt further anatomical imaging or biopsy 3 5 7.

Serial Monitoring and Follow-Up

• Tracking Progression:
  • Repeat scans are valuable for monitoring disease progression, especially in autoimmune conditions. For example, stable or improving scores indicate good disease control, while worsening scores may prompt treatment escalation 6 11.
• Treatment Response:
  • Improvement in scan parameters after therapy (e.g., steroids, immunosuppression, or antibiotics for infection) can objectively confirm clinical benefit 3 6 11.

Integration with Other Tests

• Multimodal Approach:
  • Scintigraphy is often used together with ultrasound, MRI, or CT to provide a comprehensive view—functional imaging is complemented by detailed anatomical assessment 9 10 12.

Conclusion

Salivary gland scan tests are versatile, safe, and informative tools in modern medicine. They offer objective, quantitative evaluation of gland function and structure, supporting the diagnosis and management of a wide range of disorders, from autoimmune diseases to tumors.

Key Points:

• Salivary gland scan tests are used to assess gland function, detect tumors, monitor infections, and track disease progression 2 3 5 6 7 9 10 11 12.
• Scintigraphy remains the gold standard for functional imaging, while ultrasound excels at detecting structural abnormalities 2 3 6 7 8 9 10 11 12.
• Interpretation of results involves assessing uptake patterns (normal, decreased, increased, “hot,” or “cold”) to inform diagnosis and guide treatment 3 5 6 7 9 10 11.
• Serial scans and advanced imaging modalities such as SPECT/CT and PET/CT are enhancing the accuracy and utility of salivary gland imaging 4 8.
• Collaboration between imaging and clinical findings ensures optimal patient care and follow-up.

If you or someone you know is undergoing a salivary gland scan, understanding these principles can help you navigate the process with confidence and clarity.