[Intraductal ultrasound in the pancreaticobiliary duct system]

The power of resolution of conventional imaging methods is too low for the diagnosis of very small pancreaticobiliary tumours. High-frequency ultrasound transducers (20 MHz), adapted to the dimensions of the pancreaticobiliary systems (2 mm diameter), make intraductal ultrasound examination possible during endoscopic retrograde cholangiopancreatography (ERCP). In a prospective study the invasiveness and diagnostic value of intraductal ultrasound (IDUS) was compared with ERCP, endosonography (ES) and computed tomography (CT).

During ERCP in 51 consecutive patients an intraductal ultrasound transducer was introduced into the pancreaticobiliary duct system, the results being compared with those obtained with the other imaging modalities and histopathological findings, if available.

IDUS of the pancreatic and bile duct systems is a rapid, simple and reliable method during ERCP and provides valuable additional information on periductal tissues. In the diagnosis of carcinoma of the pancreas its sensitivity was 75% (six of eight cases), that of ERCP 37% (3/8), ES 50% (4/8) and CT 37% (3/8). In the diagnosis of biliary tract tumour the sensitivity of the different modalities (in the above order) was 89% (8/9), 78% (7/9), 33% (3/9) and 33% (1/3). Specificity was 67% (2/3), 67% (2/3), 67% (2/3) and 33% (3/9); predictability 89%, 88%, 75% and 60%.

The use of small ultrasound catheter transistor system in the biliary and pancreatic ducts, introduced during ERCP, is technically simple and has few complications. It is a valuable addition to ERCP in the precise diagnosis of small pancreaticobiliary lesions.