The most common methods for staging esophageal cancer are endoscopic ultrasonography (EUS) and computed tomography (CT). EUS is well established in differentiating between early tumor stages and more advanced primary lesions. When combined with fine needle aspiration, EUS has become an important tool in assessing the regional lymph nodes, as well. EUS has its limitations, esophageal obstruction makes passage of the endoscope beyond the tumor nearly impossible and with a narrow field of evaluation, it is not useful for detecting metastatic disease. CT allows for assessment of local tumor invasion while simultaneously providing information regarding distant disease. Its usefulness locally, however, is limited. CT and EUS yield anatomic visualization. Fluorodeoxyglucose (FDG)-positron emission tomography (PET) can provide functional information and is an effective diagnostic modality in esophageal cancer. Its role in the management of esophageal cancer includes staging as well as potential utility in the evaluation of neoadjuvant therapy response and in follow-up after definitive therapy. FDG-PET will likely be more readily used in combination with anatomical imaging like CT to provide additional diagnostic information to aid radiation oncologists in target delineation and planning. In addition, FDG-PET has also been shown to have prognostic value that can be applied to patient management and aid in development of emerging therapies.