Evaluation and localization of lymphatic drainage and sentinel lymph nodes in patients with head and neck melanomas by hybrid SPECT/CT lymphoscintigraphic imaging

In patients with head and neck tumors, preoperative lymphoscintigraphy can be used to map lymphatic drainage patterns and identify sentinel lymph nodes. However, it is very difficult to determine the exact locations of head and neck sentinel nodes on preoperative lymphoscintigraphy without the use of anatomic landmarks. Lymph nodes in the head and neck are grouped into 7 regions, or levels, on the basis of anatomic landmarks. In patients undergoing standard lymphoscintigraphy, obtaining lateral marker images that show important anatomic landmarks can help with the localization of sentinel nodes. However, technical problems often render marker images of little or no use. Hybrid SPECT/CT lymphoscintigraphic imaging facilitates the localization of sentinel nodes by reliably showing the relationships between sentinel nodes and important anatomic structures. After reading this article, the reader should understand the lymph node level classification system for head and neck melanomas, be able to describe the technique used for the imaging of sentinel nodes in the head and neck region, and be able to demonstrate how SPECT/CT lymphoscintigraphic imaging can enable precise sentinel node localization and thus help to ensure minimal dissection.