Lymphoscintigraphy is a specialized medical imaging technique that provides pictures of the lymphatic system. It is a type of nuclear medicine test, using a small amount of a radioactive substance, called a radiotracer, to visualize internal body structures and their functions. This method helps healthcare providers locate lymph nodes and observe the flow patterns of lymph fluid throughout the body. The images produced, known as scintigrams, can reveal conditions in their early stages.
Understanding Lymphoscintigraphy
Lymphoscintigraphy evaluates the lymphatic system, a network of vessels and nodes that transport lymph fluid and immune cells throughout the body. The procedure involves injecting a small amount of a radiotracer, such as technetium-99m-labeled nanocolloids, which emits gamma rays. These are detected by specialized cameras that create images of the lymphatic pathways.
This technique is useful in oncology for identifying the sentinel lymph node(s), which are the first lymph nodes to receive lymphatic drainage from a tumor. If cancer cells spread, they are most likely to travel to these nodes first. For breast cancer, lymphoscintigraphy helps determine if cancer cells have spread to the axillary lymph nodes, located in the underarm, or to the internal mammary chain. This information is important for staging cancer and guiding treatment decisions, such as whether an extensive surgical procedure like axillary lymph node dissection is needed.
The Procedure for Breast Cancer
The lymphoscintigraphy procedure for breast cancer typically occurs the afternoon before or the morning of surgery. It is an outpatient procedure, meaning patients usually go home the same day. Patients may be asked to change into a hospital gown and remove any jewelry that might interfere with imaging.
Before the radiotracer is injected, a healthcare provider will clean the skin with an antiseptic. A numbing medicine is often injected around the nipple area and sometimes near the tumor to minimize discomfort. Once numb, a small amount of the radiotracer, such as Technetium-99m, is injected into these sites. The injection may cause a brief stinging sensation or a feeling of warmth or cold as the substance circulates.
After the injection, patients are often asked to gently massage the area to help the tracer move into the lymphatic system. A waiting period follows, ranging from 30 minutes to an hour or more, allowing the radiotracer to travel through the lymphatic channels and accumulate in the lymph nodes. Imaging is then performed using a gamma camera, with the patient lying still on a table. The camera captures images as it hovers over or rotates around the breast and underarm region. The entire imaging process can take between 30 minutes to two hours, depending on the individual and protocol.
Interpreting the Findings
The images produced by lymphoscintigraphy provide a visual map of the lymphatic drainage from the breast. By tracking the radiotracer, healthcare providers identify the specific lymph nodes that are the first to receive lymph fluid from the tumor site. These are known as the sentinel lymph nodes. The images show where the radiotracer has accumulated, appearing as “hot spots” that indicate the location of these nodes.
Identifying the sentinel lymph node is an important step in breast cancer management. If the sentinel lymph node is free of cancer cells, it suggests the cancer has likely not spread to other lymph nodes, potentially allowing patients to avoid a more extensive surgery like axillary lymph node dissection. This less invasive approach can reduce the risk of complications like lymphedema, a condition involving swelling due to lymphatic system blockage. While lymphoscintigraphy identifies the sentinel node, it does not directly indicate the presence of cancer cells; a biopsy of the identified node is still needed to determine if cancer has spread.
Patient Considerations
Patients do not need to follow dietary restrictions or special preparations before a lymphoscintigraphy procedure. It is advisable to wear comfortable, loose-fitting clothing and leave jewelry at home, as metal objects can interfere with imaging. Patients should inform their healthcare provider about any current medications, vitamins, or supplements they are taking, as well as any possibility of pregnancy or if they are breastfeeding.
The procedure is generally well-tolerated, with minimal risks. The radioactive substance used is a very small amount and typically clears from the body within a day or two. While the injections may cause some temporary discomfort, such as a stinging or aching sensation, serious side effects like allergic reactions to the radiotracer are rare. After the procedure, most patients can resume normal activities immediately. Any post-procedure instructions will be provided by the healthcare team.