Endoscopic ultrasound.

Indications and the clinical utility of endosonography have evolved as new technology, such as linear array echoendoscopes and EUS-guided fine needle aspiration, has emerged. The most noteworthy of the EUS applications are for cancer staging; including rectal, pancreatic, lung, and esophageal malignancies. There is little doubt that EUS is a powerful tool for cancer imaging, but its clinical impact in patient care and management has yet to be validated in prospective outcome studies. Other imaging modalities such as positron emission tomography (PET), dual-phased helical CT, and MR imaging technology will undoubtedly provide increasingly accurate diagnostic and staging information for gastrointestinal diseases. EUS imaging alone may assume a less significant role in relation to these noninvasive modalities in the future. EUS-guided FNA, as well as therapeutic EUS applications, will likely continue to expand in scope and play an important role in clinical medicine for many years to come.