Introduction

Lymphoedema occurs when the lymphatic system is unable to properly drain the protein-rich fluid in the body; the affected area swells visibly. It affects more than 200,000 people in the UK.¹ affects limbs like the arms and legs, or uncommon areas like the chest wall, abdomen, neck, and genitals. When the lymphatic system is impaired, two types of damaged lymph drainage can be recognised, primary and secondary lymphoedema.¹

Primary lymphoedema 

This congenital or genetic malfunction may occur early in life. When your lymphatic system gets overwhelmed, it can determine how severely the lymphatic system is affected, known as primary lymphoedema. There are no clear external causes, as it is inherited.²

Secondary lymphoedema

Secondary Lymphoedema is much more common. This can occur in any cancers that involve lymph node removal or radiation, for example, breast cancer, genital cancers and skin cancers.² Other causes include injuries, infection and chronic vein injuries. This happens later in life or when there is severe trauma to the lymph vessels.²

Some symptoms may include:

• Swelling
• Heaviness or tightness in the affected area
• Fibrosis (Thickened or hardened skin)
• Frequent infections (like cellulitis) 
• Discomfort or aching in the swollen area
• Restrained movement
• Sepsis

If left alone, symptoms may worsen. It can affect your daily life and your mentality. It will be difficult to live independently. You will feel frustrated because of the constant discomfort, anxiety due to emotional distress, and insecurity, as the swelling is not visually appealing.¹

This picture is an example of Lymphoedema in the leg. ¹ The skin would feel quite hard, and it would be difficult to walk because of the chronic discomfort and the restricted motion, like walking or wiggling your toes.

Importance of accurate diagnosis for treatment planning

To choose the most effective treatment, doctors will look into what kind of lymphoedema, how severe it is and what the underlying causes are. An accurate diagnosis ensures a treatment plan that is safe, specific and effective.

Introduction to imaging as A key diagnostic tool

Imaging technology will help understand the extent of the condition, other than medical history and physical examinations. The internal view of the lymphatic system will confirm the diagnosis, assess the flow of lymph fluid, identify the location, treatment, and track progress. Early imaging leads to better outcomes.

Why imaging is needed in lymphoedema

Imaging helps differentiate the lymphoedema from other causes. Conditions like lipedema, chronic venous insufficiency, and deep vein thrombosis are similar but need different treatments. To distinguish the difference, doctors rely on imaging to confirm their diagnosis, in addition to information such as physical signs and family history.³ Imaging will evaluate any underlying anatomical conditions to give a more confident diagnosis. Clinicians will stage the condition

The lymphatic system needs to be assessed to find out its structure and its functions. Different tests have specific techniques to determine the stages of the disease. Tests will give doctors a detailed insight into any anatomical abnormalities for diagnosis, predicting outcomes, and reaction to the treatment over time.³ Ongoing monitoring is needed.

There are alternative, conventional choices like exercise therapy and manual lymphatic drainage to stimulate the lymphatic system. Advanced approaches, like lymphatic bypass surgery to be more accurate. Healthcare providers tailor each treatment to the patient's needs so the disease can progress functionally. It will support the patient’s needs for long-term management.¹

Lymphoscintigraphy

This diagnostic technique is a nuclear medicine scan, called Lymphoscintigraphy. The technique is used to evaluate the condition of the lymphatic system. It has a radiotracer to track lymph flow. Nuclear medicine can examine the early stages of the disease and determine if your body is adapting to the treatment. It is a non-invasive treatment, except for the potential injection of the radiotracer, inhalation of gas, or swallowing it.⁴

How it works

The lymphatic system is made up of small channels that carry the lymph fluid throughout the body. The radiotracer can detect fluid and gather molecular information through gamma rays. A special camera projects the image of gamma rays to envision the flow through the vessels. The data produced could be the lymphatic blockages, fluid leaking into the skin, and damaged lymph nodes. The doctor can determine if the patient has lymphoedema and how far along the condition is. Any functional irregularities are easily found, and the doctors have a visual of the tracer’s movement over time. This test is low risk, involves little radiation exposure, and usually takes up to two hours.⁴

Limitations

The image it produces is not clear, meaning low spatial resolution. The function of the lymph can be determined because of its sensitivity, but smaller notes of the structure are not as detailed.⁴ It takes time to create an image and may take days to get the right area.

The radiation exposure is usually safe. To certain people, like pregnant women or children, it has a higher risk even at low levels. This applies to people who have had multiple screenings over time.⁴

Best used for

• Accurately diagnosing the functional aspect of the lymphatic flow throughout the body and determining if it is dysfunctional
• Assist in planning surgeries because of the pathway of lymph vessels for lymphoedema

Magnetic resonance imaging (MRI)

An MRI is a high-resolution, non-invasive technique to generate an image of the soft tissues. It uses magnetic fields and radio waves. The detailed images will pinpoint the dilated lymphatic channels and how much fat is stored throughout the limb. ⁵ 

How it works: MR Lymphangiography

A different type of MRI, MR Lymphangiography, scans the lymphatic system specifically. It can use a contrast agent, a special dye to find the lymphatic vessels more clearly, or without contrast. Contrast can help track the flow of fluid and damaged areas. Without contrast, it highlights the tissue structure and fluid analysis, and may be safer for people with allergies to the constant agents. ⁶ 

It assesses the fluid mass, fibrosis and distinguishes other types of swelling. Any small changes in the skin and tissue will be detected as it specialises in soft tissue contrast. The screening process can be repeated as many times because there is no radiation to detect any potential growths and thick, fatty tissues. It is safer.

Limitations

An MRI is highly requested because of its high definition image, but it is not widely available because MRI machines require a special facility, making it expensive. The machines are costly to operate, patients may not be able to afford a test, and patients need approval from their insurance. The machine is motion sensitive because it is enclosed, and patients will be uncomfortable due to the space. If the patient has any metal, they are ineligible because the MRI uses powerful magnets.⁴

Best used for

• Structural analysis
• Pre-surgical planning
• Differentiating lymphedema from other oedema types

Ultrasound

Ultrasounds are widely accessible. It uses sound waves for real-time imaging of the skin and underlying tissues, for support and diagnosis. The scan does not show the lymphatic vessels; it only examines the changes caused by lymphoedema.⁷

How it works

Doctors measure the skin, subcutaneous thickness, and any fluid buildup. It differentiates lymphoedema from other conditions. It can detect the fluid density and fluid accumulation. It is safe for repeated use because there is no radiation. Ultrasounds are portable, low-cost, and require little setup; even general practices have them. It tracks treatments and detects early signs of tissue changes, by eye or by touch. This helps doctors find the right therapy and monitor the response.⁷

Limitations

The results vary because of the technician's experiences, making it operator-dependent. This may affect the accuracy of the results. Ultrasounds cannot show a visualisation of the lymphatic vessels directly. Only the changes of the lymphatic system.⁸

Best used for

• Monitoring treatment, especially in early lymphoedema
• Differentiating between soft tissue changes (e.g., lipedema vs lymphedema)⁸

Comparing imaging techniques

Diagnosing and monitoring lymphoedema uses different imaging techniques, which can go hand in hand with one another, but some have specific advantages. A doctor’s decision on the appropriate screening determines the patients' well-being and end goal.

Lymphoscintigraphy is best for its function on the lymphatic system, and if there are any abnormalities. The downside would be the exposure to small amounts of radiation and the detail of the image. It is average in terms of cost and accessibility.

An MRI is great for structure and some functions, especially MR lymphangiography. It has a detailed resolution to reveal the soft tissues and their problems like fluid buildup, fibrosis and changes in lymph vessels. There is no radiation, and it can differentiate causes. Unfortunately, it takes time, money to implement, and is less accessible.

Ultrasound will be best for structure, cost and accessibility. It shows the image in real-time and has no radiation exposure. It only monitors changes in fluid, the thickness of skin and fibrosis. It will not be beneficial long-term since the results will not be fully understood with the lack of images of the lymphatic vessels.

Summary

Lymphoscintigraphy, MRI, and ultrasound each provide unique insights into lymphedema, and can work together most of the time to give an accurate diagnosis..

With a consultation,  the doctor will diagnose the patient with the results from the diagnostic imaging tools. It is up to the patient whether they will move forward with the plan, look at the stages they will go through, and if they want to go through with the treatment with constant monitoring.

Using different imaging techniques offers the most comprehensive evaluation.

FAQs

Q: Which imaging test is best for early lymphedema?

A: Lymphoscintigraphy is best for early detection

Q: Is MRI better than lymphoscintigraphy?

A: MRIs will give a more detailed anatomy of the lymphatic system. Lymphoscintigraphy will assess the flow. Ideally, they can be done together. However, lymphoscintigraphy will be best functionally.

Q: Are these tests painful?

A: No. Lymphoscintigraphy will cause mild discomfort because of the radiotracer. MRI requires you to lie down, but it may be loud. Ultrasounds are the most comfortable and non-invasive.