Endoscopic Ultrasonography (EUS) is a technique That combines direct vision of digestive endoscopy with ultrasound. In practice , During the same procedures you can perform a traditional endoscopy and an intracavitary ultrasound . The idea to apply a small ultrasound probe at the tip of a gastroscope was in the early 80s of Prof. Di Magno, an expert in pancreatic diseases, to better visualize this organ difficult to explore with traditional ultrasound . The first prototypes, used later for many years afterwards, were radial scan instruments with sound waves generated by mechanical probes, performing scans at 360 ° with an axis perpendicular to the instrument. In practice it is possible to obtain images with sections similar to those of Computed Tomography with the advantage of bringing the probe very close to the organs to be studied and then with a higher resolving power. This allows therefore to view better the pancreas, the gallbladder and bile ducts, the liver, the mediastinum, the perineum and some vascular structures, and, to have a detail on gastrointestinal wall unsurpassed by most other modern radiologic methods (CT and MRI). Because of these characteristics EUS has become the most accurate method for the study and preoperative locoregional staging of tumors of the intestinal wall (esophagus , stomach , duodenum , and rectum) and for the identification and preoperative staging of pancreatic tumors. It’s also one of the most accurate methods for the study of the bile ducts and gallbladder in particular for the identification of the biliary stones. More recently, in additions, an important role in the staging of lung cancer has emerged. The most recent development of electronic probes has allowed the entry on the market of new generation tools with improved imaging and the possibility of further top applications : such doppler, elastography, harmonic tissue imaging and the use of contrast media. However, certainly the more relevant innovation has been the application of linear scanning probes placed on the same axis of the instrument. These probes allow us to follow the route of accessories that exit from the operating channel of instruments such as needles, thus allowing tissue withdrawal from gastrointestinal wall or extraparietal organs. Moreover, the characteristics of new instruments with larger working channel are giving impetus to interventional procedures: such as extraluminal drainage of fluid collections or bile ducts drainage in the event of ERCP failure. Probably the major limitation of the method is the difficulty and the long training required to become experts in the technique and to be able to maximize their benefits. Specific training of the nursing staff is also necessary .
• locoregional staging of digestive tract tumors ( esophageal carcinoma , gastric carcinoma and lymphoma , rectal cancer ). From the staging of these tumors depend both the prognosis, both therapeutic choices . After excluding the presence of distant metastases (M) performing EUS allows accurate assessment of parietal extension of the tumor (T). The visualization of the structures that surround the digestive tract also allows you to suspect the presence of metastases to regional lymph nodes (N) and carry out a cytological confirmation of this obtaining tissue (FNA). This assessment can also be useful for testing the down- staging after neoadjuvant therapy. The refinement of the staging of digestive neoplasms allows you to address each patient to the most appropriate therapy , be it endoscopic , surgical , oncology or palliative care; this results in the execution of surgery only in patients with operable neoplasms (minimizing the thoracolumbar / exploratory laparotomy , for the presence of tumors too extensive to obtain a radical resection ), whilst reserving palliative care or oncology in more advanced cases.
• differential diagnosis of subepithelial lesions of the digestive tract . On the basis of sonographic appearance and the parietal layer of origin , you can assume the type of tumor under examination ( leiomyoma , stromal tumors , neuroendocrine tumor , lipoma , ectopic pancreas , cysts, varicose veins ); in doubtful cases the evaluation of the Doppler signal and performing the FNA allows you to get a more accurate differential diagnosis.
• differential diagnosis of solid pancreatic lesions (carcinoma , focal chronic pancreatitis , neuroendocrine tumors , lymphoma, metastasis). Using ultrasound evaluation and cytological confirmation (FNA) ; locoregional staging (after excluding distant metastases) in the case of malignant tumors, to undertake a choice between surgery and palliation .
• differential diagnosis of pancreatic cystic lesions ( serous cystadenoma , mucinous cystadenoma , cystadenocarcinoma , intraductal papillary mucinous tumor , neuroendocrine tumors , or metastases with liquid component , pseudocysts ) by ultrasound evaluation, cytology and biochemistry of cystic fluid analysis ; subsequent evaluation of the indications for surgery, endoscopic (drainage of pseudocysts ) or just follow up.
• research of early changes associated with chronic pancreatitis
• search of bile duct stones of even small dimensions , especially in the case where , in the light of the framework clinical, laboratory and trans-abdominal ultrasound, the probability of such pathology appears not sufficiently high to justify the immediate execution of an ERCP ( from only perform therapeutic purposes ) .
• diagnosis and locoregional staging of neoplasms of the extrahepatic biliary, with the possibility of a FNA confirmation , especially after brushing transpapillary not diagnostic .
• staging of non-small cell lung cancer. The display and the ability to perform FNA of mediastinal lymph nodes (also stations can not be reached by bronchoscopy ) is making EUS an indispensable tool for determining treatment decisions to be taken, even after neoadjuvant radio-chemotherapy. The easy approach to the mediastinum makes EUS FNA also useful in the study of other kinds of lymphadenopathy (TB, sarcoidosis, Hodgkin’s disease ).
• EUS interventional: drainage of pancreatic pseudocysts (procedure easier and safer than done blindly) celiac plexus neurolysis (for pain from chronic pancreatitis and pancreatic cancer ).