The differentiation among the Gastrointestinal Subepithelial Tumors (SETs) represents a clinical challenge. Endoscopic Ultrasound (EUS) alone may be ineffective in differentiating SETs subtypes, and tissue sampling of these lesions may be technically difficult. EUS Elastography (EUS-E) has been applied to many gastrointestinal diseases, providing a qualitative/semi-quantitative stiffness analysis, but only few studies have examined the role of EUS-E in the diagnosis of SETs. In addition, the use of contrast agents has improved the diagnostic performance of the EUS, especially in the differentiation between GISTs and other gastrointestinal SETs.

The aim of the study is to examine the performance of EUS-E and Contrast Enhanced-EUS (CE-EUS) in distinguishing among different gastrointestinal SETs subtypes. EUS patterns of different techniques will be compared to the final diagnosis gained by the analysis of histopatological specimens (surgical resection or EUS-FNB) or imaging/clinical follow-up.

Inclusion Criteria:

• Patients with GI SETs scheduled for EUS-FNB
• Patients with age > 18 but <85 years

Exclusion Criteria:

• Patients with GI SETs <15mm
• severe coagulopathy defined as abnormal prothrombin time (PT) or partial thromboplastin time (PTT) that does not normalize after administration of fresh frozen plasma
• severe cardiopulmonary diseases and severe chronic kidney disease defined as glomerular filtration rate (GFR) < 15 ml/min
• known allergic disposition to SonoVue®
• pregnancy

Patients with subepithelial gastrointestinal tumors