Ultrasonic examination of the pancreas.

Gray scale scanners allow the demonstration of much more anatomical detail than was possible with the older type scanners. The initial step in the ultrasonic examination of the pancreas is display of the anatomical detail of the portal vasculature which provides a guidepost to the pancreas. Pancreatitis is characterized by a diffusely enlarged echo-free pancreas. Pancreatic pseudocyst is almost always an echo-free unilocular fluid collection. The size of a pancreatic pseudocyst can be measured so that progress can be assessed. Pseudocysts located in the region of the tail of the pancreas may be best demonstrated by scanning from the back over the left kidney. Pancreatic pseudocysts may be partly solid. Pancreatic carcinoma appears as a localized relatively echo-free, poorly defined solid mass which attenuates the ultrasound beam. Pancreatic carcinoma smaller than 2 cm in diameter are particularly difficult to diagnose by ultrasonic examination. Pancreatic carcinoma may be difficult to distinguish from chronic pancreatitis. Dilated bile ducts can be demonstrated and point to extrahepatic biliary obstruction. Serial ultrasonic scans have been suggested as a means of monitoring the response of pancreatic tumors to therapy. The relative diagnostic value of endoscopic retrograde cannulation of the pancreatic ducts and ultrasound has not as yet been established. Ultrasonic examination is easier to perform and less expensive than any other pancreatic imaging procedure other than the upper gastrointestinal barium examination.