الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Endoscopic ultrasound (EUS) is the marriage of ultrasound and endoscopy by incorporating an ultrasound transducer in the tip of endoscope allowing imaging of different layers of the bowel wall and adjacent structures. There are two forms of EUS, donated as radial and linear. Radial EUS was first developed in 1980 for better imaging of the pancreas and when it came into use, staging of gastrointestinal (GI) tumours was its main indication. In the early 1990s, the linear EUS was developed, and this created the opportunity for endoscopic ultrasound guided fine needle aspiration (EUS-FNA). In the evaluation of esophageal tumours, EUS coupled with FNA is considered the most accurate method for loco-regional staging despite advances in spiral CT and positron emission tomography (PET) scanning. The role of EUS is to identify patients who should receive neoadjuvant therapy or undergo immediate surgical resection, and restaging after the patient has received chemo and radiotherapy. In the evaluation of gastrointestinal Subepithelial lesions, EUS is an essential modality in the evaluation of any lesion that appear to be larger than 1 cm on endoscopic examination, as it not only differentiate subepithelial lesions from extraluminal structures, but also identify the layers of origin and endosonographic characteristics of the intramural lesions with higher accuracy than barium contrast radiography, ultrasonography, CT, and MRI. EUS can also determine which lesions require additional tissue sampling, endoscopic follow up or surgical resection. In the evaluation of solid pancreatic tumours, EUS is extremely useful in the evaluation of patients with suspected or confirmed pancreatic malignancy with accuracy at least comparable to, if not superior to, CT and MRI, and is reasonably accurate for the detection of vascular invasion and resectability. EUS-FNA is an accurate method of obtaining a cytological diagnosis prior to treatment and may identify unsuspected tissue diagnosis. EUS elastography has been recently introduced in clinical practice for the evaluation of tissue elasticity allowing differentiation between benign and malignant lesions of lymph nodes and the pancreas. EUS has also emerged as the best modality to further evaluate pancreatic cysts. A combination of EUS morphology, fluid cytology and Carcinoembryonic antigen (CEA) or amylase levels improve accuracy in detecting malignant cystic lesions. EUS has developed into an important therapeutic tool for endoscopy. A therapeutic EUS intervention may comprise EUS-guided injection for therapeutic purposes, EUS-guided drainage procedures, EUS-guided resection or EUS-guided tumour therapy. EUS has now become an essential tool in gastrointestinal endoscopy. Although EUS was originally designed as an imaging tool, the procedure has evolved into a means of guiding tissue acquisition and a variety of therapeutic applications. The development of EUS has occurred over a relatively short period of time and the pace of development will most likely continue for at least the next decade.