REF019 - Lymphoscintigraphy

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

Lymphatic system and lymph node imaging is performed by injecting small quantities of technetium-99m labelled nanocolloid subcutaneously in the tissues drained by the lymphatic system which is being investigated. The radiopharmaceutical is removed from the interstitial fluid by the lymphatics and travels along the normal lymphatic channels before lodging in normal regional or secondary lymph nodes. The investigation demonstrates, therefore, the normal lymphonodular function and anatomy of the lymphatics.

Lymphatic and lymph node imaging of the lower limbs is useful in assessing the patency of lymphatic drainage following traumatic injury and in assessing suspected lymphoedema. Lymphoedema may be bilateral caused by congenital absence of lymphatics (Millroy's Disease) or unilateral. In cases of traumatic injury or lymphoedema, the initial clinical indication is usually unexplained swelling.

Imaging is needed at various times following administration of the radiopharmaceutical to assess passage through the lymphatic system. By 4 to 6 hours, the lymphatic ducts should have been visualised. In some cases, however, lymphatic transportation is slow and it may be necessary to undertake late imaging on the day following administration.

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 fulfils one of the referral criteria detailed in the following section titled 'Referral Criteria'. 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:

1. The diagnostic question is unclear.
2. The diagnostic question cannot be answered by the investigation.
3. 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.

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

The clinical indications are detailed below.

There is no specific patient preparation.