Pancreatic multicenter ultrasound study (PAMUS).

Aim: To describe the typical CEUS pattern of pancreatic lesions and to evaluate the diagnostic accuracy of Contrast-enhanced ultrasound (CEUS) in their characterization.

Materials And Methods: All US and CEUS examinations of focal pancreatic masses performed in six centers during a period of five years were reviewed. Inclusion criteria were: focal pancreatic mass pathologically proved, visible at ultrasound (US) and studied with CEUS. All lesions were then evaluated for size, aspect and enhancement pattern. Sensitivity, specificity, positive and negative predictive values with 95% CIs were calculated to define diagnostic accuracy of CEUS in respect to pathology. Diagnostic confidence of US and CEUS, discerning between benign and malignant lesions, were represented by using ROC (receiver operating characteristics) curves. Agreement was evaluated by means of k statistics.

Results: 1439 pancreatic lesions were included. At CEUS the lesions were divided into solid (89%) and cystic (12%) masses and classified into six and eight categories, respectively. Among the solid lesions, adenocarcinomas were characterized with an accuracy of 87.8%. Among the cystic lesions, cystic tumors were diagnosed with an accuracy of 97.1%. ROC curve area increased from 0.637 for US to 0.877 for CEUS (p<0.0001). Inter-observer agreement was slightly higher for solid (k=0.78) than cystic (k=0.62) lesions. In none of the centers side effects were reported.

Conclusion: CEUS is accurate in the characterization of pancreatic lesions. CEUS should be considered as a complementary imaging method for pancreatic lesions characterization.