The intent of this study is to compare the performance of the CLA-EUS versus the FV-EUS in the performance of EUS-FNA of patients with solid lesions of the GI tract and of adjacent organs, with the aim of establishing for which lesions and from which location the capability of the FV-EUS will be superior, equal or, inferior to the CLA-EUS

Recently, a forward viewing linear echoendoscope (FV-EUS) has been developed with the aim of potentially expanding the therapeutic applications of EUS. This prototype is a modification of the CLA scope and it is characterized primarily by a shifting of the orientation of the endoscopic and US views from oblique to forward. The US transducer is located adjacent to the working channel, at the endoscope tip, to display a forward-viewing image along to a scanning plane that is parallel to the insertion direction with a 90° scanning range. It has a 3.7 mm working channel without elevator, which allows exit of the FNA needle or any other accessory used parallel to the longitudinal axis of the scope.

Preliminary experiences with this scope have reported potential advantages over the conventional linear scope (CLA-EUS) for pseudocysts drainage and for hilar biliary strictures. Moreover, a large experience still unpublished from the Catholic University, Rome, Italy in the use of the FV-EUS for FNA of solid and cystic lesions throughout the GI tract has shown the FV-EUS to be highly effective with a performance that seems at least comparable to that of the CLA-EUS. To date, however, no data comparing the performance of both scopes for FNA of target lesions are available to better clarify the advantages and disadvantages of one scope over the other.

We designed a randomized comparative trial in which patients will be randomized to undergo examination with CLA-EUS or with FV-EUS. In case of failure of: (i) visualization of the presumed lesion; (ii) failure in performing the FNA with the scope used based on randomization, a second attempt will be made using the other scope.

Inclusion Criteria:

1. Presence of a solid lesion in the GI tract or in one of the adjacent organs identified at abdominal US, CT, MRI/MRCP that needs to be samples with EUS-FNA because unresectable or because tissue characterization is needed to decide further treatment modalities
2. Age greater than 18.
3. Absence of histological or cytological confirmation of malignancy.
4. Informed consent obtained.

Exclusion Criteria:

1. Patients with active coagulopathy that cannot be corrected after administration of plasma.
2. Resectable lesions that does not need tissue characterization to decide treatment modalities.
3. Pregnancy.
4. Patients who cannot give inform consent.