The purpose of this study are the evaluation of imaging ability of the main pancreaticduct, the lumens surrounding the pancreas, pancreatic cystic and solid lesions in t:heihtraductal ultrasound (IDUS). The subjects were pancreatic diseases (2 cancer, 13 mucin-producing tumor (3 main duct type and 10 branch type, 1 islet cell tumor, 8 chronic pancreatitis, 2 focal pancreatitis and 2 pancreatolithiasis) practiced by IDUS at a frequency of 30 MHz (CVIS Inc.) and 20MHz (ALOKA Co. Ltd.). IDUS was performed at one endoscopic examination in all cases, We examined the imaging limit of the IDUS at a frequency of 30 MHz and 20 MHz about the main pancreatic duct (MPD), intraductal tumor, pancreatic solid and cystic tumor, pancreatic parenchyma in the inflammatory diseases and the lumens (veins and the bileduct) surrounding the pancreas. The MPD were imaged as three layers in 23 of 28 cases by IDUS at a frequency of 30MHz and one high layer in 15 of 28 cases at 20 MHz. In the main duct type mucinproducing tumor, the intraductal tumor could be imaged less than 10 mm at a diameter by the IDUS at 30 MHz and more than 10 mm at a diameter by the IDUS at 20 MHz in detail. The tumor size imaged by IDUS at 20 MHz was less than 30 rnm at a diameter in the cysticlesions and less than 20 mm at a diameter in the solid lesions. The adequate frequency of IDUS was 20 MHz in the evaluation of the pancreatic parenchyma of chronic pancreatitis and pancreatolithiasis. In focal pancreatitis, the periductal fibrosis could not be imaged by IDUS at 20 MHz, but could be demonstrated by IDUS at 30 MHz in detail. IDUS at 20 MHO could image whole cross section of the splenic vein, the portal vein and supramesenteric vein in all cases. The adequate frequency was 20 MHO for the imaging of lesions in the head and uncinate process of the pancreas and in the body and tail of the Dancreas with dilated mail Dancreatic duct. In conclusion, we provided a basic idea for interpreting IDUS images. The adequate frequency should be selected for the proper diagnosis of pancreatic diseases in IDUS.
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