ARFI of pancreatic cystic lesions

Purpose: To prospectively evaluate the results of ARFI (Acoustic Radiation Force Impulse) ultrasound in the study of pancreatic cystic lesions using different analysis methods, compared with the final diagnosis (pathological or by MRI/EUS findings). Material and Methods: 38 patients with pancreatic cystic focal lesions were included in the study and underwent conventional US. For every patient 5 measurements with Virtual Touch Quantification ROI were performed. In order to distinguish mucinous (potentially malignant) from serous cystic lesions (mainly benign) the result “XXXX/0” was considered meaning simple liquids (reportable to water), and the accuracy of Virtual Touch Tissue Quantification in differentiating cystic-pancreatic lesions was calculated. To consider the lesion as containing complex fluids, (potentially mucinous), two different reading methods were applied: at least two numerical values when performing five measurements; prevalence of numerical values irrespective of the number of measurements. Sensitivity, specificity, positive and negative predictive value and accuracy were calculated for the differential diagnosis between mucinous versus non-mucinous cystic lesions. . Results: Sensitivity, specificity, PPV, NPV and accuracy in the group of cystic lesions by using the first reading method were respectively of: 68.8%, 77.3%, 68.8%, 77.3%, 73.7%. Sensitivity, specificity, PPV, NPV and accuracy in the group of cystic lesions by using the second reading method were respectively of 37.5%, 100%, 100%, 68.8%, 73.3%.. Conclusion: ARFI can be useful in non-invasive characterization of pancreatic cystic lesion during the conventional US examination.