Contrast enhanced endoscopic ultrasound and detective flow imaging for characterization of gastric neuroendocrine neoplasms

Gastric neuroendocrine neoplasms (GNENs) are rare tumors classified into three types: Type I, the most common typically indolent, is associated with chronic atrophic gastritis (CAG) and hypergastrinemia; type II arises in the setting of Zollinger–Ellison syndrome; type III is sporadic and often aggressive with highmetastatic potential [1]. The European Neuroendocrine Tumor Society guidelines underscore the pivotal role of endoscopic ultrasound (EUS) for GNENs > 1 cm (regardless of the type) and for all type III, providing the precise assessment of lesion size, depth of invasion and presence of locoregional lymph nodes. GNENs typically appear as hypoechoic, well-defined, intramural lesions located in the second or third echo layer [2, 3]. Ancillary techniques such as contrastenhanced EUS (CH-EUS) and detective flow imaging (DFI) enhance B-mode EUS diagnostic capability. CH-EUS allows the real-time evaluation of vascular perfusion after injection of the contrast agent, showing a typical hyperenhancement in the arterial phase followed by early wash-out in low-grade lesions as highlighted for pancreatic NENs [4]. DFI is a novel modality that visualizes low-velocity microvascular flow with higher spatial and temporal resolution than conventional color Doppler