Differentiation of cystic pancreatic neoplasms and pseudocysts by conventional and echo-enhanced ultrasound.

Abstract

Echo-enhanced sonography is a non-invasive and increasingly used procedure for the differentiation of pancreatic tumors. However, the diagnostic accuracy of this procedure compared to conventional ultrasound for the differential diagnosis of cystic pancreatic neoplasms from pseudocysts has never been investigated in a prospective study. Thirty-one patients with a cystic pancreatic lesion at the conventional ultrasound (mean age 57 years, range 36-82 years) were included in the study. Sonography was performed by an experienced examiner who was unaware of the patients' clinical diagnosis. The exact diagnosis was based on histological evidence from biopsy examination (surgical or transabdominal fine needle biopsy for all cystic neoplasms and five pseudocysts), or a follow-up of at least 18 months (four pseudocysts). Of the 31 patients, 19 had cystadenomas, three had cystadenocarcinomas, and nine had pseudocysts. Only 27% of the cystadenomas and 67% of the pseudocysts could be correctly classified by conventional ultrasound. Conversely, 95% of the cystadenomas (P = 0.0001) and all pseudocysts were diagnosed correctly by echo-enhanced sonography. The sensitivity of echo-enhanced sonography with respect to diagnosing cystadenoma was 95% and its specificity was 92%. The corresponding values for pseudocysts were both 100%. Echo-enhanced sonography has a high sensitivity and specificity in the differential diagnosis of cystic pancreatic tumors. With this procedure the differentiation of cystadenomas and pseudocysts can be improved. However, histology is the standard of reference.