Overview of Lymphoscintigraphy
Lymphoscintigraphy is a type of medical image testing that helps map the lymphatic system – the part of your body that helps fight infections. This test has been used since the 1600s, starting with the discovery of the main parts of the lymphatic system. In the late 1700s, scientists described how lymph, a fluid in your body, drains from the breast. They found two main paths for this – the axillary lymph nodes (under your arm) and the internal mammary nodes (near your chest).
By the end of the 20th century, a new method was developed using special agents that make the lymph nodes show up more clearly on the scan. This helped doctors identify the “sentinel lymph node”. This is the first lymph node that fluid from a certain area of your body drains into. Currently, a substance called Technetium Tc 99m sulfur colloid is commonly used for this purpose. The goal is to find a substance that moves quickly to the lymph nodes and stays there for a long time to make the scan clearer.
Knowing the path of the lymph fluid is important, especially in cancer cases like skin or breast cancer. The sentinel lymph node is most likely to contain cancer cells if they have spread. By examining this node, doctors can decide if more treatments like radiation, chemotherapy, or surgery are needed. If there’s no cancer in the sentinel lymph node, other treatments may not be necessary.
Today, lymphoscintigraphy is a standard part of treatment when managing certain cases of breast cancer and skin cancer. It can also be used to evaluate lymphedema, a condition in which extra lymph fluid builds up in tissues and causes swelling.
Anatomy and Physiology of Lymphoscintigraphy
The lymphatic system works much like a drain, removing a fluid called lymph from our bodies. This fluid is very similar to plasma, the liquid part of our blood. An image of the system can be seen in a procedure called Lymphoscintigraphy.
The first understanding of how this system works goes all the way back to 1874. Since then, we’ve learned about different ‘zones’ of the skin which are connected to certain parts of the lymphatic system.
Four main areas of skin on your middle body generally have lymph draining to either the underarm or groin areas. However, if the skin is near the border of these zones, the drainage pattern can be less predictable, making it a little more complicated. Doctors often find that after a surgery, these patterns can change quite a bit.
Under normal circumstances, most of the lymph from the breast drains to the lymph nodes in the same-side underarm. About 3% of the breast lymph drains to the nodes along the breastbone, and a small portion drains to the nodes between the ribs. While this pattern isn’t usual, it’s less important clinically. There’s also a complex web of lymphatic vessels around the nipple area, which doctors use to locate a certain lymph node.
A type of skin cancer called malignant melanoma often occurs on the skin of the lower body parts and midbody. The lymph nodes in the same-side underarm drain the upper body parts, and those in the groin area drain the lower body parts. Even though the drainage system for this kind of skin cancer is pretty straightforward, doctors often discover unusual draining locations, like the center area of the midbody. Other unexpected drainage sites may be certain muscle areas.
Why do People Need Lymphoscintigraphy
Lymphoscintigraphy is a medical test used in various situations:
– It might be used along with other methods to assess the stage of breast cancer in a patient and plan the appropriate treatment.
– The procedure is used to find the ‘sentinel’ lymph node, which is the first lymph node that cancer would likely spread to from a primary tumor. This is particularly helpful for patients suffering from malignant melanoma, a serious type of skin cancer. The test helps in treatment planning.
– Lymphoscintigraphy is used to diagnose and evaluate disorders related to lymphatic flow such as chronic lymphedema. Lymphedema is a condition where there is swelling in the body’s tissue due to a blockage in the lymphatic system.
– This test might also be used to look at conditions like chylous ascites or chylothorax. Chylous ascites is when a type of digestive fluid called chyle collects in the abdomen. Chylothorax is a condition where this fluid accumulates in the chest.
– Finally, lymphoscintigraphy can be utilized when checking for specific types of gynecologic cancers.
When a Person Should Avoid Lymphoscintigraphy
Lymphoscintigraphy is a procedure that allows doctors to see how fluid is moving through your body’s lymphatic system. This is very useful in detecting diseases or blockages. However, not everyone is suitable for this procedure. In particular, people with conditions that affect their lymph nodes, known as “clinically positive nodal disease”, should not undergo this procedure because of potential risks.
On the other hand, some people may not be completely barred from lymphoscintigraphy, but should be cautious. For example, if someone is allergic to radioisotopes (a type of radioactive substance) or other materials used to prepare the radiotracer (a substance doctors use to see how fluid moves through the lymph system), they may want to consider other options. Pregnant women should also avoid the procedure, as any form of radiation can be harmful to the unborn baby. Lastly, if someone has significantly altered anatomy, perhaps due to a previous treatment or surgery, the procedure may not work as expected and should be reconsidered.
Equipment used for Lymphoscintigraphy
In order to carry out a lymphoscintigraphy – a special type of body imaging scan that shows your lymph system at work – some specific tools are needed. Here’s what these tools are and what they do:
* A Collimator: This is a special type of lens that focuses the gamma rays used in this scan. The specific type usually used is called a low-energy, all-purpose, parallel (LEAP) collimator.
* A Gamma Camera: This camera captures the gamma rays and creates the image of your lymph system. It’s like an X-ray machine, but for gamma rays.
* A Gamma Probe: This is a special tool that detects gamma rays during your surgery. It helps the surgeon see the radioactive material inside your body.
* A Radiotracer: This is a liquid that’s injected into your body, and it contains a small amount of radioactive material. The most commonly used radiotracer is called technetium Tc 99m sulfur colloid, but others are available too. Sometimes the radiotracer will be filtered through a 22-μ millipore filter to ensure its purity.
* A pH-balanced 1% lidocaine additive: Sometimes, this pain relief medicine can be added to the radiotracer. This is not always done, and it depends on the practices followed at the hospital or clinic.
Preparing for Lymphoscintigraphy
Before having a procedure called lymphoscintigraphy, your doctor will need to know your complete medical history. They will also review any previous imaging tests you’ve undergone. It’s important that your doctor knows if you are pregnant, so this will be confirmed and properly recorded. Your doctor will explain the reasons for the procedure, the potential risks and benefits, and any other options you may have. This is to make sure that you’re well informed before agreeing to the procedure.
During the discussion, your doctor will mention that you might feel some discomfort during the procedure, particularly when the radioactive dye (called a radiotracer) is injected. You will be asked to remove any jewelry or objects that could interfere with the imaging process. This is especially important for necklaces that could block the view of lymph nodes near your breasts. The area of your body where the radiotracer will be injected will also be checked, marked, and cleaned to prepare for the procedure.
When you’re having the lymphoscintigraphy performed, you will normally be asked to lie flat on your back or stomach on the examination table. If you’re having the lymphoscintigraphy to check for breast cancer, you may need to hold your arms in a certain position during the procedure, to imitate the position you would take during surgery.
How is Lymphoscintigraphy performed
Radiotracer activities are used in medical techniques and can differ based on the specific institution or hospital. Lymphoscintigraphy, which is a special type of imaging that looks at lymph nodes and vessels in the body, typically uses radiotracer activities between 0.1 and 10 mCi. These doses may be adjusted depending on when it is given in relation to a planned surgical procedure.
There are different ways to inject the radiotracer, including injecting it around the tumor (peritumoral), under the skin (intradermal), around the areolar (periareolar), or under the areola (subareolar). However, the choice of method typically doesn’t significantly influence how well the sentinel lymph node can be identified. A sentinel lymph node is the first lymph node that cancer cells are most likely to spread to from a primary tumor.
The techniques for these procedures may vary from institution to institution, however, there are some common practices:
* For examining skin cancer or other skin disorders, the radiotracer is usually injected under the skin around the location of the skin disease.
* When assessing breast cancer, a mix of deep and surface radiotracer injections can help avoid false-positive results. False positives occur when the test incorrectly shows that a certain condition or attribute is present.
* For patients with lymphedema (swelling in an arm or leg caused by a blockage in the lymphatic system), it’s usually preferred to inject both the affected limb and its healthy counterpart simultaneously.
After the radiotracer is injected, doctors perform imaging for 30 to 60 minutes. They focus on the direction they expect the lymph fluid to flow. If there’s intense activity at the injection site, they may need to reduce it using a lead shielding. Massage might be applied to the injection area to help distribute the radiotracer. To get images, they often use a Cobalt-57 source, and taking pictures from different angles may help to identify the lymph nodes.
Possible Complications of Lymphoscintigraphy
Lymphoscintigraphy is a mostly harmless procedure with few side effects. One problem that could occur is called radiopharmaceutical extravasation, but this just means that the medical substance used in the test accidentally leaks into the surrounding tissues – it doesn’t have any long-term effects. Sometimes, a person may have an allergic reaction to the tracer material used, but this is rare. The allergic reaction is more likely to be from the preparation materials, like a drug called lidocaine.
What Else Should I Know About Lymphoscintigraphy?
The sentinel lymph node, often the first node where cancer may spread, plays a key role in outlining treatment plans for patients diagnosed with breast cancer or skin cancer (melanoma). Whether or not this lymph node is infected with cancer can guide decisions about further treatment, including more intensive surgical options.
There are risks associated with the removal of lymph nodes in the armpit (or the axillary area), such as lymphedema (swelling caused by a blockage in the lymphatic system). This risk makes a procedure called lymphoscintigraphy even more valuable. This process allows doctors to examine single lymph nodes to detect disease. It also helps them use staining techniques in a more focused way, potentially improving the detection of cancer cells.
In the past, doctors often removed many lymph nodes in an attempt to control the spread of the disease. However, thorough studies have shown that removing more lymph nodes does not necessarily lead to longer survival. Therefore, the development of effective lymphoscintigraphy methods has become increasingly essential.
The use of the Sentinel lymph node identification and biopsy has also shown to be a useful tool for intermediate-thickness melanoma patients, as it has eliminated the need for lymph node removal in patients for whom such intervention would bring little benefit. In melanoma patients, removing additional lymph nodes following identification of cancer in the sentinel lymph node showed no significant increase in survival benefits.
