A patient’s physician may order a sentinel node injection to identify the sentinel lymph node, or the first node to receive the lymph drainage from a tumor. The procedure may be ordered to plan a biopsy or surgery that will help assess the stage of cancer and create a treatment plan.

Small amounts of radioactive materials, called radiotracers, are typically injected intradermally and/or subcutaneously. The radiotracers enter into the lymphatic system and eventually end up in the major lymphatic beds. The radiotracer emits energy in the form of gamma rays. The gamma rays are detected by a tool the surgeon will use to locate the lymph nodes. This study is able to pinpoint activity in the body on a molecular level. As a result, a sentinel node injection procedure offers a great opportunity to identify a wide range of lymphatic diseases and disorders in its earliest stages.

A sentinel node injection procedure will require a very small amount of a radioactive tracer to be injected intradermally and/or subcutaneously around the tumor site or site of interest. The patient will be placed in a sitting or lying position depending on the location of the site to be evaluated. The entire procedure usually takes 15 to 20 minutes. 

Typically, the patient may change into a gown before the exam. However, in many cases, the patient will be allowed to wear their own clothing. You may be asked to leave your jewelry and other accessories at home or remove them prior to the exam. These objects may interfere with the procedure. Women should always tell their doctor and technologist if they may be pregnant, pregnant, or breastfeeding before the study. Your doctor will tell the patient how to prepare for their specific exam.