Linear Endoscopic Ultrasound

Abstract

The widespread acceptance of endoscopic ultrasound (EUS) has largely been due to the emergence of the linear array echoendoscope. Once endosonographers familiarized themselves with images obtained from the radial echoendoscope with correlative gastrointestinal and extraintestinal anatomy, they reached a certain plateau. Elegant descriptions of lesions and superior staging abilities were soon met by the obvious reality of the need for tissue acquisition. The rapid refinement of the linear array echoendoscope, both in endoscope design and imaging resolution coupled with an improvement in the size of the accessory channels quickly brought this technology to the forefront. This chapter reviews the basic endoscope design of the linear array echoendoscope. The dogma for learning EUS is the need for a systematic approach guided by a ``station approach.{''} We describe the basic techniques used to acquire the necessary images when performing a linear examination. As one masters these maneuvers, performing fine needle aspiration and other therapeutic interventions will seem secondary. The second half of this chapter explores the literature, namely asking the question, does the instrument matter and how useful is the linear array endoscope in comparison with the mechanical radial instrument for evaluating esophageal cancer, gastric cancer, pancreatic disorders, suspected common bile duct stones, and lastly rectal cancer. The linear array echoendoscope is an extremely powerful instrument and the benefits derived from using this instrument will be well worth the energy expended in mastering some basic concepts and techniques.