Current efforts have been centered on diagnosing the occult lymph node metastasis accurately by using image modalities, CT, MRI, US, and PET, so that appropriate therapy can be administered. However, their limitations of spatial resolution and visualization have prevented them to diagnose the subclinical lymph node metastases effectively. Sentinel lymph node biopsy allows identification of occult metastases more accurately and more effectively. This procedure has been introduced for oral carcinoma as same as for several solid malignancies. In this procedure, small gamma cameras have the potential to be used to facilitate the procedure. The advancing technology, including nuclear medicine, molecular imaging, and optical imaging, has the promise to provide greater information on biological and anatomical characterization of the diseases and treatment for this challenging field．
