Salivary Gland Scintigraphy

Salivary gland scintigraphy is a diagnostic nuclear medicine procedure that serves as a noninvasive examination method to check the function of the salivary glands. The procedure is based on indirect imaging of the salivary glands by detecting (using detectors to determine) the tissue that contributes to saliva secretion (saliva release). As a result of the different amount of saliva that can be secreted by each salivary gland, the parotid gland (parotid gland) and submandibular gland (submaxillary gland) can be imaged with particular precision.

Indications (areas of application)

  • Sialadenitis (salivary gland inflammation) – salivary gland scintigraphy can be used to diagnose both chronic and acute sialadenitis (salivary gland inflammation), which can be of viral or bacterial genesis (origin).
  • Rheumatic systemic diseases – salivary gland scintigraphy is used particularly frequently in diseases of rheumatic origin, as these are often accompanied by sicca symptomatology. Sicca symptomatology is understood as persistent dryness of the salivary glands, which can present as xerostomia (dry mouth) or dryness of the eye (conjunctivitis sicca). Sicca symptoms are often an expression of Sjögren’s syndrome, which is a collagenosis (autoimmune disease). Heerfordt’s syndrome, which is a chronic inflammation of the parotid gland and lacrimal gland, is also an indication for the use of the procedure.
  • Radioiodine therapy – therapeutic treatment with radioactive iodine can contribute to the destruction of the parenchyma (tissue) of the salivary glands. The damage caused by this can be detected with salivary gland scintigraphy.
  • Sialolithiasis (salivary stone disease) – in the area of the salivary glands can form salivary stones, which are associated, among other things, with a massively increased risk of inflammation.
  • Tumors – The detection of tumors of the salivary glands can be performed with salivary gland scintigraphy. Adenomas (benign tumor of the glandular tissue), carcinomas (malignant tumor of the skin and mucous membranes) but also metastases occur particularly frequently in this area.

Contraindications

Relative contraindications

  • Lactation phase (breastfeeding phase) – breastfeeding must be interrupted for 48 hours to prevent risk to the child.
  • Repeat examination – no repeat scintigraphy should be performed within three months due to radiation exposure.

Absolute contraindications

  • Gravidity (pregnancy)

Before the examination

  • Food abstinence – the patient should not have consumed food or fluids for at least one hour before the examination.
  • Application of the radiopharmaceutical – depending on age, height and weight, a defined amount of 99mTc-pertechnetate is administered via intravenous injection. The application is performed under camera control.

The procedure

Following the administration of the 99mTc pertechnetate, 30 minutes of imaging data are obtained. After another 20 minutes, the patient is administered lemon juice or ascorbic acid dissolved in water to stimulate salivary gland function. Increased salivary secretion causes massive excretion of the radiopharmaceutical. In the subsequent functional analysis of the measured values, the time-dependent function of the four major salivary glands is evaluated (assessed). For the evaluation of the measured values, it is of decisive importance that the patient moves as little as possible in order to be able to ensure adequate recording quality. On the basis of the examination, various parameters can be assessed so that a pathological (diseased) process can be detected and classified. In the presence of acute inflammation of the salivary glands, perfusion of these is increased, with enhanced uptake of the radiopharmaceutical. In contrast, however, the release of the pharmaceutical is reduced. If a chronic inflammatory process is present, a markedly reduced perfusion and pharmacon uptake can be observed, with the release of the radiopharmaceutical being reduced. In the case of sialolithiasis (salivary gland stone disease), on the other hand, all parameters are reduced.Also, a parenchymal disorder (tissue alteration) due to radioiodine therapy leads to a reduction of all measurement parameters. Although there are various methods for assessing the salivary glands that do not require radiation exposure, salivary gland scintigraphy is a useful assessment method for various pathological (pathological) processes because it is a non-invasive method that allows physiological (natural) imaging of gland parenchymal function. Because of this, the method is particularly suitable for carrying out progress controls during pharmacotherapy (drug therapy). Furthermore, it represents the gold standard in the evaluation of xerostomia (dryness of the oral cavity).

After the examination

No special measures are necessary after scintigraphy. The procedure is usually performed on an outpatient basis.

Possible complications

  • Intravenous application of radiopharmaceutical may result in local vascular and nerve lesions (injuries).
  • Radiation exposure from the radionuclide used is rather low. Nevertheless, the theoretical risk of radiation-induced late malignancy (leukemia or carcinoma) is increased, so that a risk-benefit assessment should be performed.
  • Allergy – allergic reactions to ingested food are possible. Based on this, a food allergy should be excluded in the medical history.