Endoscopic ultrasound (EUS) combines ultrasound technology with endoscopy to better visualize the tissues of the digestive tract and adjacent anatomical structures inside the human body. This internal vantage point provides more detailed pictures of the GI tract, including the esophagus, stomach, small bowel and colon[i] as well as surrounding tissues and organs.
Now, physicians at Methodist Medical Center trained in the multidisciplinary field of endosonography are using this technology in a variety of applications to help them stage cancers such as esophageal, gastric, rectal and pancreatic cancers; diagnose diseases of internal organs; locate common bile duct stones; and evaluate masses in the submucosal lining of the GI tract or in enlarged stomach folds.
Endoscopic ultrasound is performed using either a probe, which is passed through the channel of a standard endoscope, or with an echoendoscope — a special endoscope with the ultrasound transducer located on its tip. With the transducer positioned in close proximity to the target tissue, EUS imagery better defines the layers of the GI wall as well as surrounding tissue and organs.[ii]
EUS has two primary advantages over conventional ultrasound and endoscopy. Conventional ultrasound is performed by placing a transducer against the skin to produce images of internal organs. With EUS, the transducer is endoscopically inserted into the body via the digestive tract. This puts the transducer closer to the area of interest to obtain higher resolution imagery.
The second advantage of EUS is that it allows physicians to see internal organs without making an incision. In conventional endoscopy, the gastroenterologist can only view the innermost lining of the digestive tract or its wall. The addition of ultrasound allows the endoscopist to see beyond that wall to visualize all five layers of the GI tract as well as surrounding tissue and organs. EUS works by transmitting high-frequency sound waves that are bounced off the body’s internal tissues; the echoes are then converted into a computerized picture called a sonogram.
From a clinical perspective, this means that an abnormality below the surface of the digestive tract wall — such as a growth that was detected at a prior endoscopy or under x-ray, or a suspicious mass on an internal organ — can be further evaluated under EUS, helping doctors better understand its nature and prescribe the best treatment option.
Because EUS can be used to visualize other organs outside the digestive tract, endoscopic ultrasound plays an important role in diagnosing diseases of the pancreas, bile duct, liver, spleen and gallbladder as well as assessing a variety of cancers. In addition, EUS is useful in therapeutic applications such as tissue sample collection, removal of cysts or aspiration of lymph nodes, making it an ideal, minimally invasive alternative to exploratory surgery.
If you or anyone you know is suffering symptoms of digestive internal organ disorders, they may benefit from endoscopic ultrasound examination.
[i] American Society for Gastrointestinal Endoscopy (ASGE). “Media Backgrounder, Endoscopic Procedures.”
[ii] American Society for Gastrointestinal Endoscopy (ASGE). “Technology Status Evaluation Report, EchoEndoscopes.” Gastrointestinal Endoscopy, 2007;66:435-442.