Added value of intravenous contrast-enhanced ultrasound for characterization of cystic pancreatic masses: a prospective study on 37 patients

The aim of this study was to evaluate the added value of contrast-enhanced ultrasound (CEUS) in the pancreatic cystic mass (PCM) diagnosis by using a qualitative and quantitative analysis in order to make a relevant characterization. Patients and method: Between December 2008 and November 2011, 37 patients with PCM discovered at ultrasound examination were prospectively followed. A qualitative and quantitative CEUS analysis was performed in order to differentiate etiologies of the PCM. In the quantitative analysis several parameters were followed: Peak Intensity (PI), Time to Peak (TTP), maximum ascending gradient (GRAD), Time to maximum gradient (TTG) and Area Under the Curve (AUC). Normalized ratios were also calculated. In all patients a definite cytological or histological diagnosis was obtained. Results: Thirty-seven patients were studied: 12 with pancreatitis-associated pseudocyst and 25 with cystic tumors (10 serous cystic adenoma, 5 mucinous cystic adenoma, 6 cystadenocarcinomas, 2 solid pseudopapillary tumors and 2 intraductal papillary mucinous neoplasms). There was a significant difference of the nAUC and nTTP between pseudocyst and cystic tumors, p=0.03 and p=0.01, respectively. A normalized TTP value above 7 sec was suggestive for the diagnosis of pseudocysts with 79.16 % accuracy. There was a significant difference of nTTP and nTTG between the benign and malignant lesions. nTTP < 9 sec and nTTG < 8.5 sec rules out malignant cysts in almost 90% of cases. Conclusion: The CEUS is useful in the diagnosis of PCM. The quantitative analysis of the enhancement of the cystic wall may discriminate the different types of the PCM.