Sentinel Node Imaging

Sentinel Node imaging was introduced it served as a means to reduce the number of lymph nodes excised during surgery, thereby reducing the morbidity rate in women undergoing the procedure. The concept is to establish the path that cancerous cells may take along the lymphatic channels, allowing for metastic cells to travel to other organs.

Debate has often been raised as to whether there is a need for imaging or not. Surgeons have requested patients receive the injection and go right to surgery...

The proceeding example demonstrates a reason to image the patient, which is first and foremost to ensure the injection is good and the materials is traveling through the lymphatic channels. But secondary to determine where the radiopharmaceutical is traveling.

This patient presents with right breast cancer, pre-lumpectomy and lymph node dissection. The patient was positioned in a right oblique position and injected with 500 uCi Tc99m sulfa colloid with Lidocaine by subcutaneous injection to the right of the nipple. When the patient was placed under the camera it was noted that there were lymphatic tracks above and below the injection site.

On the next image a lead blocker was placed over the injection site and imaging was continued at 2 minute intervals.

Although the physician was confident in the location of the sentinel node in the right axilla, he wanted confirmation that the lower track was not going to a lymph node but as altered due to the patient's previous surgery in the lower portion of the right breast. The patient was placed in the right lateral position and the right axillary node is easily identified and the lower track appears to remain in the breast tissue. No lead placed over injection site.

To further define the activity in the right breast, the patient was placed in an oblique position with a wedge under the left shoulder and imaged from the right posterior oblique position. This view allows the breast to move away from the patient's torso to further show the activity below the injection site (blue dot at site of lead blocker) is confirmed to be in the breast tissue.

As the radiologist put it, this became an exercise in obliques to best find the view that would confirm the activity was indeed in the breast and not traveling to a lymph node.