lymphoscintigraphy
Meaning of lymphoscintigraphy: A scan that follows a trace of radioactive material through lymph channels to map where fluid from a given area drains.
Definition of lymphoscintigraphy
Lymphoscintigraphy is an imaging test that maps the lymph system by injecting a small amount of radioactive tracer into tissue and following where it travels. A gamma camera detects the tracer as it moves along lymph channels and collects in lymph nodes. The test shows which node receives drainage first from a particular site, and whether lymph flow is delayed or blocked.
How is the test done?
A tiny volume of tracer, usually a radioactive substance bound to particles small enough to enter lymph channels, is injected just under the skin near the area of interest. Muscle movement and tissue pressure carry it into the vessels. Images are then taken over minutes to hours, and the tracer appears as bright spots where it accumulates. The radiation dose is small, and the injection site rather than the whole body carries most of it.
What is it used for?
| Purpose | What the scan shows |
|---|---|
| Sentinel node mapping | The first node draining a tumor |
| Swollen limb assessment | Whether lymph flow is blocked or slow |
| Planning surgery | Which drainage basin to explore |
| Fluid leak | An abnormal route taken by lymph |
Why does the first node matter so much?
Lymph from any patch of skin or tissue drains in a predictable order, reaching one node before the others. If tumor cells have started to spread through lymph channels, that first node is where they arrive first. Finding it with lymphoscintigraphy allows a surgeon to remove and examine only that node, a sentinel lymph node biopsy, instead of clearing the whole group. Clearing a whole group carries a lasting risk of lymphedema, persistent swelling of the limb caused by the loss of drainage routes. Drainage is not always where anatomy textbooks predict, particularly for tumors on the trunk, where lymph from one site may travel to more than one basin. Mapping each person individually is the point of the test.
Also known as
Used in a sentence
Lymphoscintigraphy identified a single sentinel node in the axilla.
Good to know
Lymph drainage does not always follow textbook anatomy, particularly for tumors on the trunk, which is why mapping is performed for the individual rather than assumed.
Word origin
Where “lymphoscintigraphy” comes from
Combines the Latin lympha, meaning clear water, with scintilla, a spark, and the Greek graphein, to write or record.