Lymphoscintigraphy

Lymphoscintigraphy is a nuclear medicine scan that allows doctors to study how lymph is transported through the lymphatic system. To do this, a small amount of a radiopharmaceutical is injected under the skin and images are taken at various intervals to track its path.

It can provide information when lymphoedema is suspected or when a better understanding of how the lymphatic drainage system functions is required. In people with lipoedema, it can be used to investigate whether there is also an associated lymphatic disorder, but it does not, on its own, confirm or rule out lipoedema.

What is a lymphoscintigraphy and what does it enable us to investigate?

A lymphoscintigraphy is a nuclear medicine scan; nuclear medicine is a speciality that uses small amounts of radioactive substances for diagnostic purposes to assess the functioning of organs and systems.

In this case, the lymphatic system is examined; this consists of a network of vessels and lymph nodes involved in collecting and transporting the fluid accumulated between tissues. This fluid, known as lymph, circulates through the lymphatic vessels before re-entering the bloodstream.

To track its path, a radiopharmaceutical is administered – that is, a medicine containing a very small amount of radioactive material which acts as a tracer. In lymphoscintigraphy of the arms or legs, it is usually administered via small injections under the skin.

A gamma camera detects the signal emitted by the tracer from outside the body and produces images as the tracer moves. In this way, the specialist can assess how it progresses through the lymphatic pathways and whether it reaches specific groups of lymph nodes as expected.

When it may be indicated

The test is mainly used when there is a suspicion that lymphatic drainage is not functioning properly and the patient’s medical history and physical examination require further information.

Not all cases of swelling require a lymphoscintigraphy. Whether it is indicated depends on what the medical team needs to clarify and whether the result can contribute to the diagnosis or to subsequent decisions.

Lymphoscintigraphy in the investigation of lymphoedema

Lymphoedema occurs when the lymphatic system is unable to transport lymph properly, leading to a persistent build-up of fluid and other changes in the tissues.

It can be primary, when it is related to abnormalities in the development or function of the lymphatic system, or secondary, when it occurs following damage to vessels or lymph nodes, for example after certain surgical procedures, cancer treatments, infections or other diseases.

Lymphoscintigraphy can help to determine whether there is a functional impairment in lymphatic transport and to better characterise how it is distributed.

It is not a mandatory test for all people with lymphoedema. In many cases, the diagnosis can be established through medical history and physical examination; imaging tests are used when they provide relevant additional information. The consensus of the International Society of Lymphology supports this clinical and individualised approach.

Lymphoscintigraphy in people with lipoedema

Lipedema is a chronic condition of the subcutaneous adipose tissue with a characteristic distribution and distinct clinical manifestations.

Its diagnosis is based primarily on symptoms and physical examination. Imaging tests may help to investigate alternative diagnoses or associated problems, but there is no single lymphoscintigraphy finding that can, on its own, confirm lipoedema.

In a person with lipoedema, lymphoscintigraphy may be considered when there is concern that there may also be impaired lymphatic drainage or associated lymphoedema.

In this context, the question is not ‘Is there lipoedema?’, but ‘How is the lymphatic system functioning as well?’. Therefore, a normal lymphoscintigraphy does not rule out lipoedema, nor does an abnormal result confirm it.

Lymphoscintigraphy and indocyanine green lymphography: what is the difference?

Although both techniques examine the lymphatic system, they use different principles and address different questions.

Lymphoscintigraphy is a branch of nuclear medicine. It uses a radiopharmaceutical and a gamma camera to track its transport through the lymphatic system and assess its progression towards the lymph nodes.

Indocyanine green (ICG) lymphography uses a fluorescent tracer and a special optical camera. It primarily visualises superficial lymphatic vessels and is particularly useful when specific pathways need to be localised, for example in certain microsurgical planning procedures.

Neither technique should be regarded simply as a more modern or more accurate version of the other. They can provide complementary information, and the choice between them depends on the clinical question.

How to prepare for a lymphoscintigraphy

The specific preparation required depends on the radiopharmaceutical and the nuclear medicine protocol. Before the test, it is important to inform the team if you are pregnant or might be pregnant, if you are breastfeeding, if you have had any previous reactions to radiopharmaceuticals or other medicines, and what treatments you are currently taking.

You should also mention any wounds, infections or significant inflammation in the area to be examined and, where available, provide reports from previous lymphatic tests.

If compression stockings, sleeves or other compression garments are used, the department must specify when to remove them and when they may be worn again. You should not alter the compression or stop taking medication on your own initiative.

Recommendations regarding food, drink, hydration or physical activity should follow the specific instructions provided by the Nuclear Medicine department.

How it is carried out and what you might feel

To begin with, the team confirms the area to be examined and explains how the various stages of the appointment will be organised.

The radiopharmaceutical is administered via one or more small injections under the skin. When the arms or legs are being examined, the injection sites are usually near the hand or foot, although the exact location depends on the protocol.

The injection may cause a stinging sensation or brief discomfort. Imaging then begins using the gamma camera, which is positioned close to the body and records the signal emitted by the tracer from outside the body.

The first images can be obtained shortly after the injections. Further images are taken later to check how the radiopharmaceutical has progressed.

In some studies, both limbs are examined even if the symptoms are more evident in just one. This comparison can help to identify differences in transport, although a symptom-free limb should not automatically be considered a perfect benchmark of normality.

Depending on the protocol, you may be asked to walk, move the limb or perform some gentle activity between image acquisitions. Muscle movement aids lymphatic transport and may form part of the examination itself.

During each scan, you must remain sufficiently still to obtain useful images. If you experience pain or find it difficult to maintain a certain position, please let the staff know so that adjustments can be made where possible.

Duration of the scan and what happens afterwards

The total duration varies from person to person. It depends on the region being examined, the protocol and the speed at which the tracer moves. For this reason, the appointment may involve several imaging phases separated by waiting periods.

Most people do not need a specific recovery period following the scan. Once the scan is complete, the Nuclear Medicine department will advise you on any temporary recommendations regarding hydration, breastfeeding or other radiation protection measures. These instructions depend on the specific radiopharmaceutical and the protocol used.

Limitations of lymphoscintigraphy

Lymphoscintigraphy primarily provides functional information on lymphatic transport, but does not show the entire anatomy of the vessels in great detail.

The result may vary depending on the radiopharmaceutical used, the injection sites, movement during the scan, the time elapsed between each image, and the interpretation protocol. Consequently, two scans carried out using different methodologies cannot always be directly compared. Nor does the test, on its own, identify the cause of lymphoedema or necessarily explain all the components of swelling.

In the case of lipoedema, its role is limited to investigating a possible associated lymphatic component. It does not allow the condition to be confirmed or ruled out.

Risks and special circumstances

The most common discomfort is associated with the small injections of the radiopharmaceutical and usually takes the form of a prick, a stinging sensation or local tenderness.

As a nuclear medicine scan, lymphoscintigraphy uses a small amount of radioactive material and involves exposure to ionising radiation. The activity administered must be justified on a case-by-case basis and kept as low as reasonably possible to obtain the necessary diagnostic information.

Reactions to the radiopharmaceutical or its components are possible. Before administration, the patient’s history of relevant hypersensitivity should be reviewed.

Pregnancy and breastfeeding

Pregnancy or the possibility of pregnancy must always be disclosed before the test.

Nuclear medicine examinations also involve exposure of the foetus to radiation; therefore, performing them during pregnancy requires a specific assessment of the benefits and the available alternatives. Breastfeeding must also be disclosed before the radiopharmaceutical is administered.

Recommendations regarding temporary cessation of breastfeeding and milk expression depend on the preparation used. Even amongst albumin nanocolloid products authorised in Spain, different timeframes apply; therefore, only the guidelines provided by the Nuclear Medicine department for the specific radiopharmaceutical being administered should be followed.

Lymphoscintigraphy and other tests of the lymphatic system

The choice of test depends on the information the medical team needs to obtain. Indocyanine green lymphography mainly allows the observation of superficial lymphatic vessels using fluorescence and can help to locate specific pathways.

Magnetic resonance lymphography can provide anatomical information about deeper tissues and structures without the use of ionising radiation. Ultrasound, including Doppler ultrasound, is useful when it is necessary to examine tissues or assess whether a venous disorder may be contributing to the swelling.

Measurements of the circumference or volume of a limb allow its progress to be monitored, but do not directly show how lymph is transported. These techniques address different questions and can be combined within the same diagnostic process.

Professionals involved

Lymphoscintigraphy falls within the field of Nuclear Medicine. At the Publio Cordón Memorial Hospital, the Nuclear Medicine Unit forms part of the Diagnostic Imaging Department and is headed by Dr Pedro Nespral Torres. The unit carries out functional studies using radiopharmaceuticals in accordance with radiation safety protocols and under specialist medical supervision.

When the test forms part of the assessment of lymphoedema, the Nuclear Medicine report must subsequently be integrated with the clinical evaluation carried out by the team treating the condition.

At Memorial, specialist care for lymphoedema is provided within the Department of Plastic and Reconstructive Surgery, which houses the Advanced Breast Reconstruction and Lymphoedema Unit. The department is headed by Dr Jaume Masià Ayala and includes, amongst other specialists, Dr José María Lasso and Dr Gemma Pons, who specialise in reconstructive surgery and surgery of the lymphatic system.

The referral for lymphoscintigraphy, the procedure itself and the subsequent use of the results are thus part of a coordinated clinical process: the test provides functional information, and the team responsible for the patient’s care integrates this with the physical examination and other tests to decide on the next steps.

Clinical guidance

Lymphoscintigraphy allows us to observe how a tracer is transported through the lymphatic system and provides information on the functioning of lymphatic drainage.

In people with suspected lymphoedema, it can help to confirm or characterise an abnormality when the clinical assessment requires further information. In people with lipoedema, it can be used to investigate whether there is also a lymphatic problem, but it does not diagnose lipoedema.

Its main value lies not in an isolated image, but in correlating the tracer’s path with the symptoms, the physical examination and the clinical question that prompted the investigation.

Medical information for general guidance

This information sheet is intended to help you understand what a lymphoscintigraphy is, how it is carried out, what you may experience during the examination, and what information it can provide about lymph flow.

This information is for general guidance only and is not a substitute for the assessment of a healthcare professional or the instructions provided by the Nuclear Medicine department.

The indication for the test, the radiopharmaceutical used, preparation, post-procedure recommendations and the interpretation of the results must be tailored to each person’s clinical situation and the centre’s protocol.