REF016 - Salivary Gland Imaging

The purpose of this document is to assist clinicians in deciding on the appropriateness of the Nuclear Medicine procedure and to give guidance on the mechanism of referral.

Technetium-99m pertechnetate is taken up by salivary glands and secreted by the ductal epithelium. A salivary gland scan can provide physiological information about the ability of the salivary glands to accumulate the radiopharmaceutical and about the drainage of saliva^[1][2]

Rapid sequential images should show progressive concentration of activity within the salivary glands and the mouth. The thyroid is also visualised and the intensity of activity is generally similar to that in the salivary glands. During imaging, the salivary glands are stimulated to drain by giving the patient lemon juice. When the salivary ducts are patent, this causes prompt salivation and drainage of the glands into the mouth.

In the normal subject, the four salivary glands all accumulate the radiopharmaceutical at the same rate and drain rapidly following stimulation. When a duct is obstructed, the uptake by the gland may be normal or slower than normal and there is no fall of activity following stimulation.

The referrer may be any clinician holding a current valid medical qualification and currently employed in Secondary Care.

Referrals from Primary Care will be accepted if the investigation has been suggested by a Consultant Radiologist in a report from a previous investigation or following discussion with a Consultant Radiologist or Secondary Care Specialist. Details of such suggestions or discussions should be included on the request form.

Referring clinicians are reminded of the requirement to avoid unnecessary exposure to ionising radiation. The investigation may already have been requested at this hospital or elsewhere and clinicians are asked to be particularly vigilant to ensure that their request is not a double request.

Requests will only be accepted if the diagnostic question fulfills one of the referral criteria below. Appropriate clinical information must be supplied to allow the investigation to be justified. It is not acceptable to simply request the investigation without appropriate clinical information.

Requests will be returned to the referrer if:

• The diagnostic question is unclear.
• The diagnostic question cannot be answered by the investigation.
• Insufficient clinical information is supplied to justify the investigation.

Requests should be submitted on the orange stripe NUCLEAR MEDICINE (ISOTOPE SCAN) request form. Patient details, Investigation required and Reason for Test/Diagnostic Question should be fully and appropriately completed and the form signed.

Note the requirement for Patient Preparation below

Sufficient clinical information must be provided to justify the investigation proceeding.

Valid clinical indications are detailed below^[1]:

• Obstruction of the salivary glands without an obvious cause.
• Traumatic abnormalities and fistulas.
• Following surgery (e.g. stenosis operations, symptoms following subtotal parotidectomy, transposition of the duct orifice or surgical denervation to prevent drooling).
• Following irradiation or high dose 131I therapy.
• Salivary gland aplasia.
• Sjogren’s syndrome.
• Warthin’s tumour.
• As an alternative to sialography e.g. in patients with a sensitivity to radiographic contrast agent or in failure to cannulate the duct.

• Patients must fast for at least 2 h prior to the investigation. They may NOT be given perchlorate^[1].
• Anticholinergic medication should be stopped during 24 h prior to the examination^[1].
• The patient should not take any thyroid blocking agents for up to 48 hours prior to scanning.