Lymphoscintigraphy is a medical imaging study in which images of the lymphatic system are obtained with the assistance of a radioactive tracer material. These studies are used for a number of different purposes, and are performed in a nuclear imaging suite by a technician who has received training in nuclear imaging. The resulting images, known as scintigrams, can be used to develop a treatment plan for the patient or to provide more information about how effectively a course of treatment is working.
In this procedure, radioactive material is injected into the area of interest. This material gives off gamma rays which are picked up by a gamma camera positioned near the patient. As they move through the lymphatic system, the camera can follow the release of radiation, creating a map of the lymphatic system in a series of images. The patient will express the small amount of radioactive material naturally.
One common reason to use lymphoscintigraphy is to identify the sentinel node near a tumor. The sentinel node is the lymph node which is first in line for lymph which drains from the tumor. Using lymphoscintigraphy, a doctor can identify this node and use this information during surgery to biopsy the node or remove the node altogether so that it can be checked for traces of the cancer. The sentinel node biopsy can reveal important information about whether or not the cancer has spread, and how far.
Another reason to use lymphoscintigraphy is in a test for lymph obstruction, such as that seen in lymphedema and lymphoma. In this case, the area of suspected obstruction will be injected with the tracer, and the lymphoscintigraphy will be used to identify the point of obstruction, if one is present. This information can be used to make decisions about a treatment plan or to collect information which will help a doctor arrive at a diagnosis.
There are some risks to this procedure. It is not recommended for pregnant women and breastfeeding mothers, as the baby could be exposed to radiation. While the radiation exposure from a single lymphoscintigraphy procedure is not a cause for concern, a doctor may be concerned about cumulative exposure over a lifetime, which can become an issue for patients undergoing cancer treatment or patients who have a history of radiation exposure for other reasons.
When a lymphoscintigraphy study is recommended, a patient should ask why the test is being ordered, what the possible outcomes might be, and whether or not any special precautions need to be observed.