Echo-enhanced ultrasound is a newly available imaging modality for the evaluation of pancreatic lesions. Neoplasms of the pancreas tend to have a characteristic vascularization pattern. Adenocarcinomas are often hypovascularized as compared to the surrounding tissue. On the other hand, neuroendocrine tumors are hypervascularized lesions. Masses associated with pancreatitis have a different vascularization pattern depending on the degree of inflammation and necrosis. Cystadenomas frequently show many vessels along fibrotic strands. Data from prospective studies have demonstrated that based on these imaging criteria, the sensitivity and the specificity of echo-enhanced sonography in diagnosing the degree of differentiation of pancreatic masses are equal to, or greater than, 85% and 90%, respectively. In conclusion, pancreatic tumors have a different vascularization pattern in echo-enhanced ultrasound. These characteristics can be used with high a diagnostic accuracy for differentiation. planning and for the evaluation of the prognosis but this difficult with current imaging techniques, even when a combination of various diagnostic procedures is employed. Although histology or cytology obtained from fine needle biopsy or surgery is the standard of reference, especially in the differential diagnosis between pancreatitis-associated lesions and adenocarcinomas, needle biopsy can produce false results due to sampling error. Endoscopic retrograde (ERCP) and magnetic resonance cholangiopancreatography (MRCP) are the current imaging standards for the differential diagnosis of pancreatic lesions [1, 2, 3, 4, 5]. With conventional transabdominal ultrasound, there are no characteristic findings for the differentiation of pancreatic masses and its diagnostic accuracy is less than 70% [6, 7, 8, 9]. Echo-enhanced ultrasound has been proposed as a valuable technique for the differentiation of liver lesions [10, 11, 12, 13, 14, 15]. We and others have demonstrated that echo-enhanced ultrasound is a valuable imaging method to evaluate pancreatic tumors [16, 17, 18, 19, 20]. In this review, we present a practical approach for the use of echo-enhanced sonography in the differential diagnosis of pancreatic masses.
Peter Malfertheiner, Steffen Rickes, Klaus Minkemuller
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