Sentinel Node Mapping

This technique illustrates how imaging may be able to reduce the need for extensive diagnostic surgery. When patients are being diagnosed with breast cancer it has been standard practice to surgically remove all of the lymph nodes under the arm to determine if the cancer has spread beyond the breast and what treatment is appropriate. Removing all the lymph nodes can result in long-term complications and discomfort for the patient from bad arm swelling called lymphedema (a condition where excess lymph fluid collects in tissues and causes swelling). Trials are underway now; however, to test an alternative, less damaging procedure in which imaging plays an important role.

In this alternative procedure, called sentinel node mapping, only the sentinel node (the first lymph node to which breast cancer is likely to spread) is removed rather than all the lymph nodes. In order to identify the sentinel node, the doctors inject either a blue dye or a relatively non-toxic radioactive substance and see which lymph node it reaches first. This lymph node is the sentinel node, and is surgically removed.

This has been done since the 1990s at many centers. It is becoming more common outside of assessment of breast tumor spread.