ENDOSCOPIC ULTRASONOGRAPHY OF THE UPPER GASTROINTESTINAL-TRACT

EUS unites two established imaging techniques and extends the range of observation into and beyond the wall of the GI tract. The close proximity of the sonographic probe to the region of interest combined with high ultra-sonic frequencies of between 7.5 and 12 MHz yields images of high resolution. EUS is used in the staging of benign and malignant neoplastic disorders of the oesophagus, stomach, pancreas and extrahepatic bile ducts. It helps to establish operability, to plan surgical approach, to follow response to therapy and to search for recurrence. The predictive value in defining the T and N stages of oesophageal carcinoma lies between 80 and 90% and 65 and 85%, respectively. It is clearly superior to CT in tumour stages T1 and T2. In gastric cancer, resectability based on the TNM staging system can be correctly assessed by EUS in 85% of cases and EUS detection and staging of early gastric cancer reaches an accuracy of 90%. The EUS accuracy rate for resectability of pancreatic carcinoma is 83% and tumour infiltration into the portal and splenic vein can be correctly determined by EUS in 94% and 67%, respectively. A reliable EUS differentiation between chronic pancreatitis and pancreatic carcinoma based on the echo pattern and outer margins is not possible. The development of EUS-guided needle biopsy should improve the specificity of EUS in this regard. Experience to date suggests as well that EUS will assume an important place in the staging of bile duct tumours. EUS has expanded our endoscopic and sonographic capabilities and it is to be hoped that further technical improvement, e.g. the construction of forward-viewing endoscopes combined with radial scanning devices, will contribute to a widespread use of this technique by gastroenterologists. © 1991.