Evaluation of upper gastrointestinal tumors with a new endoscopic ultrasound probe

During endoscopic ultrasonography (EUS), an ultrasound transducer is used to provide images of the gastrointestinal wall structure, which supplement endoscopic pictures of the mucosal surface. The technique is useful to evaluate the extent of malignant invasion of the intestinal wall and the location and histologic nature of intramural and extramurallesions.1-3 However, EUS entails certain problems. The endoscopic view is limited, especially in the esophagus, because of obliqueor side-viewing optics, so that most patients must undergo two separate examinations: conventional endoscopy and conventional EUS. Additionally, the large diameter and rigid tip of the EUS fiberscope make it difficult to pass through a malignant stricture, and considerable experience is required to learn to use the fiberscope and orient the ultrasound image. Recently, several types of ultrasound probes have been developed to overcome such problems, some of which are commercially available.4-7 These probe systems differ from conventional EUS systems in that the ultrasonic transducer is separate from the endoscope. Because they present some disadvantages, they are not widely used clinically. In this paper, we report both in vitro and in vivo (via the biopsy channel of an endoscope during conventional endoscopy) use of a new ultrasound probe.