Contrast harmonic EUS for the prediction of pancreatic neuroendocrine tumor aggressiveness (with videos)

Background and Aims: Contrast harmonic EUS (CH-EUS) has the ability to depict tumor microvasculature. Decreased microvascular density has been identified as a factor associated with tumor aggressiveness. We aimed to study the accuracy of CH-EUS for the prediction of pancreatic neuroendocrine tumor (PNET) aggressiveness. Methods: Between June 2009 and March 2015, all consecutive patients with histology-proven PNETs and CH-EUS examination were included. Nine endosonographers blindly analyzed all videos. CH-EUS tumor aggressiveness was defined as a heterogeneous enhancement at the early arterial phase. The final diagnosis of tumor aggressiveness was defined as follows: G3 tumors, morphologic and/or histologic findings of metastatic disease in G1/G2 tumors. Diagnostic values were calculated. Intratumoral microvascular density and fibrosis were assessed on pathologic specimens. Results: Eighty-one tumors were included, of which 26 were aggressive (32.1%). In CH-EUS 35 tumors (43.2%) had a heterogeneous enhancement. The overall accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CH-EUS for the diagnosis of tumor aggressiveness were 86%, 96%, 82%, 71%, and 98%, respectively. The interobserver agreement among the 9 endosonographers was good (k = .66). The intraobserver agreement was excellent for the junior (k = .83) and senior (k = .82) endosonographers. Heterogeneous tumors at CH-EUS corresponded to fewer vascular and more fibrotic tumors (P < .01). Conclusions: CH-EUS is accurate in the prediction of PNET aggressiveness and could be a decision-making element in their management.