ARRS 2022 Abstracts

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E1905. Salivary Scintigraphy Technique and Spectrum of Imaging Findings
Authors
  1. Cory Gooch; Mayo Clinic
  2. Corrie Bach; Mayo Clinic
  3. Manoj Jain; Mayo Clinic
  4. Jason Young; Mayo Clinic
Background
Salivary gland scintigraphy is a noninvasive method to assess salivary gland function. Salivary gland epithelial cells uptake and concentrate univalent anions. Intravenous pertechnetate accumulates in parotid and submandibular glands and is excreted into saliva. An oral sialogogue stimulates the production and secretion of saliva. Salivary gland dysfunction can be seen with various conditions such as Sjogren’s syndrome and other autoimmune processes, post radiation therapy, or sialadenitis. Dynamic salivary gland imaging and time activity curve analysis before and after sialogogue administration may be used to determine the functional status of the major salivary glands.

Educational Goals / Teaching Points
The goal of this exhibit is to understand the role of salivary gland scintigraphy, imaging technique, and imaging findings in various salivary gland pathologies. Multiple cases demonstrating normal and abnormal findings will be presented. Imaging protocols will be discussed, which will include patient preparation instructions, radionuclide type, administered dose, site of injection, image acquisition parameters, citric acid administration, and image interpretation.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Patient preparation is too fast for 2 hours prior to the examination. Intravenous injection of 5–10 mCi Tc-99m sodium pertechnetate is administered and imaging begins immediately. Dynamic imaging is acquired during oral administration of citric acid and salivary gland time activity curves are generated. Normal salivary gland scintigraphy demonstrates prompt radionuclide uptake, which gradually increases over time. Following oral administration of a sialogogue, such as lemon juice, normal salivary glands should demonstrate 50% or more washout of radionuclide from the gland. Abnormal scintigraphic findings include focally increased or decreased uptake within the gland. Some dedifferentiated salivary gland tumors, if large enough, can be demonstrated as a photopenic defect within the gland. Other tumors, such as Warthin’s tumors and oncocytomas, which are derived from the epithelial cells of excretory ducts, may be demonstrated as a focus of increased radiotracer uptake with no washout because they lack communication with the ducts. Chronic inflammatory processes may demonstrate decreased uptake and/or secretion, with advanced disease lacking uptake all together. Prior studies have demonstrated good correlation of scintigraphic image findings with histopathologic grading of salivary gland dysfunction.

Conclusion
Salivary gland scintigraphy is a reliable and noninvasive method to assess salivary gland function and may help characterize parotid gland tumors. Providing salivary gland scintigraphy is valuable in quantifying gland dysfunction and imaging abnormalities may precede clinical manifestations. Radiologists should be aware of salivary gland scintigraphy techniques and imaging manifestations of pathologies.