Differential diagnosis of pancreatic diseases with an intraductal ultrasound system.

Forty patients with pancreatic diseases (11 cancer, 1 islet cell tumor, 12 mucin-producing tumor, 1 teratoma, and 15 chronic pancreatitis) were studied in vivo with ERP and were also scanned with an intraductal ultrasound (IDUS) probe at a frequency of 30 MHz inserted into the main pancreatic duct. The usefulness of in vivo IDUS was evaluated by comparison of images with the ERP findings. IDUS was of diagnostic value in 18 of the 40 patients; it distinguished between 4 malignant and 6 benign causes of localized stenosis revealed by ERP, provided parenchymal information in 2 cases with only displacement revealed by ERP (1 islet cell tumor and 1 teratoma), and determined the extent of tumor in 6 cases with main-duct-type mucin-producing tumor. Ten of 11 cancer, 4 of 12 mucin-producing tumor, 1 islet cell tumor, and 11 of 15 chronic pancreatitis (previously scanned in vivo), and 2 islet cell tumor (not scanned in vivo), were resected and scanned in vitro. Fifteen normal pancreases from autopsy subjects were also scanned in vitro. The IDUS images were then compared with corresponding histopathological sections from the 15 normal pancreases and 28 post-operative pancreatic specimens. Differential diagnosis of the pancreatic diseases by echo patterns was possible in all cases except those with intraductal papillary adenocarcinoma and adenoma.