الفهرس 
Anatomy&physiology Of The LiverOnly 14 pages are availabe for public view
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Abstract
Within the increased number of patients suffering from chronic liver diseases from HCV, which may progress to cirrhosis with all its complications; clinicians and patients require accurate information about the degree of liver fibrosis to guide management decisions, monitor disease activity and predict outcome. Liver fibrosis is an excessive accumulation of ECM protein and it is the result of all chronic disease. The main source of ECM is activated hepatic satellite cells which are resident perisinsoidal in the subendothelial space between hepatocytes and sinusoidal endothelial cells and primary site for storing retinoids (vit.A) within the body. Liver cirrhosis is the end result of all chronic liver diseases and defined as replacement of liver tissue by fibrous scar as well as regenerative nodules resulting in loss of normal hepatic architecture and progressive loss of liver functions. Liver biopsy is the gold standard method for diagnosis of hepatic fibrosis. It is an invasive procedure and needs proper preparations, skilled doctors, and adequate place that contains all equipments needed to guard and to manage any complications. It is reasonable and safer to perform liver biopsy under US guidance to decrease and limit post-biopsy complications. Pain is the most frequent complication and bleeding is the most dangerous one. This has lead researchers to look for other method to assess the stage of liver fibrosis. FibroScan (Elastography) is used to stage chronic liver diseases or measurement of hepatic elasticity or stiffness.Transient Elastography (FibroScan; Echosens, Paris, France) is a novel, rapid, and non invasive technique which measures liver stiffness. Briefly, this system is equipped with a probe consisting of an ultrasonic transducer mounted on the axis of a vibrator. A vibration of mild amplitude and low frequency is transmitted from the vibrator to the tissue by the transducer itself. This vibration induces an elastic shear wave which propagates through the tissue. In the meantime, pulse echo ultrasonic acquisitions are performed to follow the propagation of the shear wave and measure its velocity, which is directly related to tissue stiffness (or elastic modulus). The harder the tissue, the faster the shear wave propagates. Recent reports have shown that liver stiffness measurement using FibroScan allowed accurate prediction of hepatic fibrosis in patients with chronic HCV infection. In patients with chronic hepatitis C, it has been shown that liver stiffness measurements ranged from 2.4 to 75 kPa, with a median value of 7.4 kPa. Fibroscan is a non invasive method for measuring liver stiffness and according to the result in Kpa that correlated to Metavir score the hepatic fibrosis may be staged with different cutoff value, however the technique has its limitations: it uses expensive equipment and has decreased accuracy in patients who have ascites. Transient Elastography is too difficult or impossible in obese patients and patients with narrow intercostals spaces, but this last limitation is to be overcome by technical development such as development of another probe. It is probable that in not too distant future the elastography could replace liver biopsy in most patients with chronic hepatitis.