الفهرس 
Anatomy of the LiverOnly 14 pages are availabe for public view
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Abstract
The progressive hepatic fibrosis with the development of
cirrhosis is a feature of almost all chronic liver diseases.
Approximately 10–20% of patients with chronic hepatitis C
virus infection have cirrhosis at first clinical presentation, and
as many 20–30% of those who do not have cirrhosis will
eventually develop this condition and its complications within
one or more decades. These complications are liver failure,
ascites, variceal bleeding, portosystemic encephalopathy, and
hepatocellular carcinoma (Foucher J et al., 2005).
Until recently, liver biopsy (LB) examination was the
only way of evaluating liver fibrosis. However, LB examination
is invasive and painful, and can have life-threatening
complications. The poor acceptability of LB examination can
lead to treatment delays, and LB examination is difficult to
repeat in poorly symptomatic subjects. The accuracy of LB
examination for assessing fibrosis also has been questioned
because of sampling errors, intra and interobserver variability
that may lead to over or under staging of fibrosis. There is thus
a need for accurate non-invasive methods of measuring the
degree of liver fibrosis. Proposed approaches include physical
examination, routine biochemical and hematologic tests,
surrogate serum fibrosis markers have been used (Castera L,
2005).TE is a simple and low-cost device that could be used to
assess instantaneously and directly the elasticity of the liver.
The measurements are fully non-invasive, and may be
performed by physicians or even non physicians after a short
training period, there is no intra or interobserver variability and
the technique is reproducible (Foucher J et al., 2006).
Correlation with fibrosis grade is good with good sensitivity
and specificity values and high positive predictive values (in
comparison to liver biopsy) especially in moderate and sever
stages of fibrosis ≥ f2 (reaches more than 90%) (Foucher J et
al., 2006).
Because the Transient Elastography completely non
invasive and because stiffness is a continuous variable, repeated
measurements could show changes in the amount of fibrosis
and help follow up in these patients (Zoil M et al., 2005).
Also elasticity measurements have good correlation with
complication of fibrosis as cirrhosis, oesophageal varices and
hepatocellular carcinoma (Foucher J et al., 2006).
Transient Elastography could be useful not only to
evaluate liver fibrosis as to monitor liver disease progression,
but also to monitor antiviral or antifibrotic therapy effects and
to help taking decisions in daily clinical practice (Gomez E et
al., 2006).
Several studies evaluated the accuracy of TE, blood tests,
or combinations compared with liver biopsy (Shiha G et al.,2009). Most of these studies include patients with HCV
infection, one includes patients with chronic liver disease of any
origin, one includes patients with biliary cirrhosis due to
primary biliary cirrhosis or primary sclerosing cholangitis, and
one includes only those patients who are co-infected with HIV
and HCV. These studies show that TE results are reproducible
across operators and time. All the studies report that TE
diagnostic performance is good, indicating that it agrees
perfectly with liver biopsy (Shiha G et al., 2009)
Elasticity measurements are difficult or impossible in
obese patients and patients with narrow intercostals spaces, also
fat tissue may absorb or diminish low-frequent vibration,
resulting in a poor signal to noise ratio that affects the elasticity
measurement algorithm in this patient. The low frequency
elastic waves do not propagate through liquids, indicating that
elastometry is impossible in patients with ascites. The chest
wall contributes to prevent the liver from being directly
compressed by the probe itself, and to give a static and plane
surface for the probe positioning. Blood flow might be another
consistent factor for the measurement It self (Saito H et al.,
2003). But this last limitation is to be overcome by technical
improvements such as the development of new probes.