الفهرس 
ANATOMY OF THE PORTAL SYSTEMOnly 14 pages are availabe for public view
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Abstract
L
iver cirrhosis represents one of the most common widespread disease in the world due to prevalence of hepatitis viruses and schistosomiasis especially in hyper enedemic nations. In addition, liver cirrhosis is one of the main causes of portal hypertension with resultant compensatory portosystemic shunting and disturbed intrahepatic circulation.
Gastrointestinal haemorrhage is the first cause of death among cirrhotic patients. The gastrointestinal haemorrhage was significantely associated with the young age (< 40 years). On the other hand, the clinical and biological parameters didn’t seem predictive of bleeding. The risk of haemorrhage is positively correlated with the presence of oesophageal varices and their stage, the gastric varices and the portal gastropathy.
In the past, the radiological investigations were very poor in visualization of varices and for accurate assessment of their site and extension. In addition, some of them were invasive and not conclusive in its finding. With advance of technology, new generations of Ultrasound devices and Multi-detector row computed tomography offer distinct advantages over traditional spiral CT. 3D CT portography becomes superior to conventional angiographic portography for detecting portosystemic collaterals.
The aim of this study is to evaluate and compare the role of MDCT angiography as a recent less invasive technique for investigating portosystemic shunts as compared to Color Coded Doppler.
Multidetector CT portography provides excellent images in the visualization of portosystemic collaterals. MDCT angiography is capable of defferentiating between submucosal and perigastric fundal varices which is of clinical interest. In addition, MDCT angiography allows identification of the afferent and efferent veins of oesophageal and gastric varices. Therefore it can augment the surgeon’s perception of potentially problematic varices by detailing the course of these tortuous vessels.
Among the three rendering techniques, MIP images provide the best visualization of portal vein and portosystemic collaterals.
Although color Doppler sonography is a useful, non invasive modality for evaluating the haemodynamics of gastric varices, it falls shortly in visualizing the detailed haemodynamics of the inflowing and outflowing vessels of gastric varices in nearly half of the patients when compared with computed tomography.
Although endoscopy is the most reliable diagnostic procedure for detecting oesophageal varices, CT portography is superior to endoscopy in visualization of submucosal fundal gastric varices and peri-oeophageal and peri-gastric varices.
CT portography and Color Doppler have proved to be non invasive and reliable methods for detection of portal vein occlusion and determining its site, extension and whether it is partially or totally occluded. In addition, they distinguish between portal vein tumour and thrombus occlusion.
There is close relationship between the velocity of the hepatofugal flow in the LGV and oesophageal variceal size. EVB was more frequent in patients with a hepatofugal flow velocity > 15 cm / s.
The cut-off value of the blood flow velocity in both splenic and portal veins between patients and healthy controls is 12 cm /s.
Consequently abnormal values of the blood flow velocities in portal hypertension is < 12 cm /s.
Color Coded Doppler can predict the site, size of the varices and its risk of bleeding according to size, blood velocity and direction of flow of the portal, splenic and left gastric veins.
These measurements reflect the severity of portal hypertension, therefore, we could select patients who are under risk of bleeding to do further assessment by CT portography and upper GIT endoscopy to predict bleeding attacks in cirrhotic patients.