Endoscopic ultrasound: Anatomy of the normal esophagus
- Frank G Gress, MD
Frank G Gress, MD
- Professor of Medicine
- Columbia University College of Physicians and Surgeons
Endoscopic ultrasound (EUS) is an endoscopic technique that provides highly accurate imaging of mucosal, submucosal, and periluminal structures. It is often used for the preoperative staging of gastrointestinal (GI) malignancies such as esophageal, gastric, pancreatic and rectal cancers for which it has an accuracy of 90, 88, and 90 percent, respectively, when performed with experienced hands [1-4].
EUS provides high-resolution imaging of the GI tract by its unique ability to differentiate the histologic layers of the GI tract wall [5-9]. The most commonly used echoendoscopes operate across a broad range of frequencies ranging from 5 to 20 MHz, with a variable depth of penetration and resolution. These echoendoscopes produce an image of the GI tract wall consisting of five sections or layers. A discussion of high frequency EUS with ranges >20 MHz revealing a nine-layer GI tract wall is covered elsewhere (see "High-frequency catheter endoscopic ultrasonography"). These layers correspond to the five distinct histologic layers of the gut wall:
●The innermost, medial layer (lumen) is known as the superficial mucosal layer
●The second layer corresponds to the lamina propria or deep mucosa
●The third layer is known as the submucosa
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