Endoscopic ultrasound
Endoscopic ultrasound | |
---|---|
MeSH | D019160 |
Endoscopic ultrasound (EUS) or echo-endoscopy is a medical procedure in which
and colon. It can be used to visualize the walls of these organs, or to look at adjacent structures. Combined with Doppler imaging, nearby blood vessels can also be evaluated.Endoscopic ultrasonography is most commonly used in the upper digestive tract and in the respiratory system. The procedure is performed by
Digestive tract
Upper digestive tract
For endoscopic ultrasound of the upper
Endoscopic ultrasound is performed with the patient sedated. The endoscope is passed through the mouth and advanced through the esophagus to the suspicious area. From various positions between the esophagus and duodenum, organs within and outside the gastrointestinal tract can be imaged to see if they are abnormal, and they can be biopsied by a process called
The technique is highly sensitive for detection of pancreatic cancer (90–95% sensitivity), particularly in patients who are suspected to have a mass or present with jaundice[citation needed]. Its role in staging patients with pancreatic cancer is limited to local metastases; however, in combination with CT scan which provides information on regional metastases, it provides an excellent imaging modality for diagnosis and staging of pancreatic carcinoma.
Endoscopic ultrasound can also be used in conjunction with endoscopic retrograde cholangio pancreatography (ERCP). The ultrasound probe is used to locate gall stones which may have migrated into the common bile duct. This occurrence may cause obstruction of the drain shared by the liver and pancreas, which may lead to lower back pain, jaundice, and pancreatitis.[citation needed]
Lower digestive tract
Echo-endoscopy can also be used for imaging of the
Respiratory tract
An endoscopic ultrasound probe placed in the esophagus can also be used to visualize lymph nodes in the chest surrounding the airways (bronchi), which is important for the staging of lung cancer. Ultrasound can also be performed with an endoscopic probe inside the bronchi themselves, a technique known as endobronchial ultrasound.
Technical aspects
The quality of the image produced is directly proportional to the frequency used. Therefore, a high frequency produces a better image. However, high frequency ultrasound does not penetrate as well as lower frequency ultrasound so that the examination of the nearby organs may be more difficult.[citation needed]
See also
- Medical ultrasonography
Footnotes