Definition of lymphoscintigraphy
Lymphoscintigraphy is the technical name for the various procedures used to study the lymphatic system. In the context of breast cancer, lymphoscintigraphy is used to identify the sentinel lymph node. (The closest draining lymph node near a breast tumor).
A sentinel, is like an army guard posted to stand watch in the wilderness, on lookout for the enemy approaching. The sentinel soldier would see the enemy first.
A radioactive colloid (usually a bulky molecule containing sulfer, and the radioactive atom: Technetium 99m) is injected into the body, along with a blue dye, and the movements of the substance is tracked and mapped out using a Geiger counter attached to a computer.
When lymph nodes take up the substance they can be identified, and removed for biopsy examination. Scintigraphy, which tracks the flow of radioactive molecules through the body, is a more general term for the technique, while lymphoscintigraphy is a way of referring specifically to the technique of identifying the lymph nodes by tracking the flow of radioactive materials. Lymphoscintigraphy is therefore a specialized form of nuclear medicine that produces pictures (scintigrams) of the lymphatic system.
The lymphatic system is part of the body’s immune system response
The lymphatic system is the network of small channels in the body which cricultate a fluid called ‘lymph‘, and cells, called lymphocytes, throughout the body. The lymph ‘nodes‘ are spots along these channels which filter foreign bodies such as viruses, germs, and pollen. Usually with breast cancer treatment, a radio tracer is injected in many sites both around the breast tumor, but also in the chest and underarm regions. The process usually takes less than one hour to complete.
Sentinel lymph node dissection to check for breast cancer metastasis
Sentinel lymph node dissection is now commonly used to exam a patient for lymph node metastasis of breast cancer, bypassing the need for extensive surgical excision of the axillary nodes.
The sentinel lymph node is typically the first node to receive the lymph drainage from a breast tumor. Lymphoscintigraphy is used to identify the sentinel node and to help plan either a biopsy or surgery to assess the breast cancer stage as treatment begins. Based on the histological evaluation of harvested sentinel nodes, the breast cancer metastasis status of the whole axilla can be predicted with a high level of confidence. the disease status of the entire axilla can be predicted. Lymphoscintigraphy can also help determine any apparent points of blockage in the lymphatic system, such as a lymphedema.
Opinions remain varied as to whether or not lymphoscintigraphy is required before a sentinel node biopsy
Lymphoscintigraphy usually permits a less extensive surgery than a more traditional approach of ‘radical surgery‘ or axillary lymph node dissection. Often lymphoscintigraphy can be undertaken in the afternoon, allowing for surgery the very next day. However, opinions are mixed as to whether or not preoperative lymphoscintigraphy improves the rate of sentinel lymph nodes identification and reduces false-negative breast cancer identifications. Lymphoscintigraphy is not required in order to perform a sentinel lymph node biopsy.
Here are a couple Q&A for you to go over…
- What are some common uses of the procedure? Physicians perform lymphoscintigraphy to identify the sentinel lymph node, or the first node to receive the lymph drainage from a tumor. Plan a biopsy or surgery that will help assess the stage of cancer and create a treatment plan. And identify points of blockage in the lymphatic system, such as lymph flow in an arm or a leg, or lymphedema.
- How does the procedure work? With ordinary x-ray examinations, an image is made by passing x-rays through the patients body. In contrast, nuclear medicine procedures use a radioactive material, called a radio pharmaceutical or radio tracer, which is injected into the bloodstream, swallowed or inhaled as a gas. This radioactive material accumulates in the organ or area of your body being examined, where it gives off a small amount of energy in the form of gamma rays. Special cameras detect this energy, and which the help of a computer, creates picture offering details on both the structure and function of organs and tissues in your body.
- What are the limitations of lymphoscintigraphy? Nuclear medicine procedures can be time consuming. It can take several hours to days for the radio tracer to accumulate in the body part of interest and imaging may take up to several hours to perform, though in some cases, newer equipment is available that can substantially shorten the procedure time. The resolution structures of the body with nuclear medicine may not be as high as with other imaging techniques such as CT or MRI. However, nuclear medicine scans are more sensitive than other techniques for a variety of indications, and the functional information gained from nuclear medicine exams is often unobtainable by other imaging methods.
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