الفهرس 
Emberiology of the GB and biliary systemOnly 14 pages are availabe for public view
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Abstract
common primary hepatobiliary cancer, after hepatocellular cancer. Although the entire biliary tree is potentially at risk, tumors involving the biliary confluence or the right or left hepatic ducts (hilar cholangiocarcinoma) are most common and account for 40%–60% of all cases. The role of imaging is to aid differentiation of benign from malignant causes of biliary stricture, determine respectability in patients with malignant disease, and preoperatively stage those patients with potentially resectable tumors. Ultrasonography is the primary investigative tool for detection of cholangiocarcinoma, which is highly sensitive for confirming biliary duct dilatation, localising the site of obstruction and excluding gallstones. In experienced hands, this non-invasive study will demonstrate the level and extent of biliary involvement and also provide information regarding tumor invasion of the periductal tissues. Duplex ultrasonography is a highly accurate predictor of vascular involvement and respectability. Computed tomography (CT) is often the initial diagnostic test for most indications in the abdomen because of its versatility and availability and because it helps to survey the entire abdomen for potential metastatic disease. Computed tomography has been a widely used noninvasive examination method for assessing biliary malignancy, local parenchymal extension, evidence of intrahepatic metastatic disease, lymph adenopathy, peritoneal spread, and vessel involvement in cholangiocarcinoma. However, helical CT has not been considered to be accurate in the evaluation of ductal extension and vascular involvement. The many recent advances in CT technology have secured its position as the modality of choice in imaging biliary and pancreatic malignancies. Multiplanar reformations, 3-D renderings, and highquality CT angiographic displays have become extremely valuable both in image interpretation and in communicating information to surgeons and referring physicians. Magnetic resonance imaging (MRI) along with magnetic resonance cholangiopancreatography (MRCP) is ideally suited to evaluate the bile ducts above and below a stricture and also identifies intrahepatic mass lesions. Because of their intrinsic high tissue contrast and multiplanar capability, MRI and MRCP are able to detect and preoperatively assess patients with cholangiocarcinoma, investigating all involved structures, such as the bile ducts, vessels, and hepatic parenchyma. The test of choice to evaluate suspected cholangiocarcinoma is cholangiography. This can be done by percutaneous transhepatic cholangiogram (PTC), endoscopic retrograde cholangiopancreatography (ERCP), or by magnetic resonance cholangiopancreatography (MRCP). Typical findings are biliary strictures in proximal ducts, and occasionally polypoid masses. Proximal extension has important therapeutic connotations and direct cholangiography allows complete evaluation of the entire biliary tree. PET/CT was particularly valuable in detecting unsuspected distant metastases that might prevent surgical therapy and result in a change of oncological management. Also, PET/CT detected all gallbladder cancers and the vast majority of cholangiocarcinomas. Future studies should evaluate whether PET/CT with the simultaneous use of intravenous contrast media would enable accurate staging of biliary tract tumors without the need for additional tests. In conclusion the detection and staging of cholangiocarcinoma is best performed by ultrasonnography, CT and cholangiography. Cholangiography demonstrates the extend of bile duct involvement better than do ultrasonography and CT especially for infiltrative tumor, and it provides a rout for biopsy. MRI is gaining in its use for staging because of its sensitivity for vascular invasion. CT is the best overall examination for tumor depection but but MRI is useful in evaluating portal vien invasion.