The use of ultrasound in the diagnosis of gastroenterological disease.

Ultrasound is high frequency mechanical vibration. As far as is presently known, there are no harmful effects of ultrasound at the energy levels used in currently available commercial ultrasonic scanners. Ultrasonic studies are independent of organ function, are painless, and require nor special preparation. Ultrasonic scanning is useful in the diagnosis of pancreatic disease, especially in the detection of complications of pancreatitis such as pancreatic abscess or pseudocyst, and in diagnosing pancreatic carcinoma. Gallstones and dilation of the biliary tree can be detected ultrasonically even when the patient is jaundiced. Primary liver tumors and hepatic metastases can often be demonstrated. Intraabdominal abscesses are better investigated by ultrasound than by any other means currently available. Ultrasonic scanning also provides a sensitive means of detecting ascites. Ultrasonic control of needle placement has been suggested for pancreatic and liver biopsy, for aspiration of intraabdominal fluid collections, and for percutaneous transhepatic cholangiography. Ultrasonic B-mode scans provide undistorted images of cross sections through the abdomen which can be used in radiotherapy planning to localize tumor masses and to place kidney shields accurately. Organ volumes can be estimated from a set of ultrasonic B-mode scans without any assumptions being made as to the shape of the organ.