الفهرس 
Anatomy of LiverOnly 14 pages are availabe for public view
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Abstract
Orthotopic liver transplantation (OLT) is currently the treatment of choice for patients with severe acute or chronic liver failure for which no other therapy is available.
Over the past several decades, advances in surgical techniques, organ preservation, immunosuppressive therapy, and early detection of postoperative complications have increased survival rates after liver transplantation.
However, there are still significant complications, particularly those of vascular origin, which can lead to graft failure and require reoperation unless prompt treatment is instituted. Vascular complication include hepatic artery stenosis (HAS), hepatic artery thrombosis (HAT), hepatic artery pseudoanyreausm, portal vein thrombosis or stenosis, IVC stenosis or thrombosis and hepatic veins thrombosis & stenosis.
Vascular complications develop in 8% of LTX cases and should be considered in patients with evidence of graft failure, biliary strictures and leaks, gastrointestinal bleeding or septicemia. Hepatic artery stenosis or thrombosis is the most common and significant vascular complication and accounts for approximately 60% of LTX vascular complications.
Early and accurate diagnosis of vascular complications is crucial for increasing the survival rate of the graft in living related liver transplantation because most stenoses or thromboses are treatable with interventional procedures and since the clinical presentation of posttransplantation vascular complications is frequently nonspecific and varies widely, imaging studies are critical for early diagnosis.
US, being cheap, safe, non invasive and accurate is the primary imaging modality in the detection and follow –up of early and delayed complications of liver transplantation.
Gay-scale US is first performed to assess the site, size and echo pattern of the transplanted liver, focal lesion of liver graft, intra or extra hepatic ducts and presence of intra abdominal fluid collection so it is an initial step and also a base line for further follow up.
Color Doppler considered the investigation of choice for early detection and late follow up of any postoperative complications even before clinical indications. It is done routinely after liver transplantation from the first day postoperatively, and it is performed after gray-scale US.
Combined use of color and spectral Doppler US parameters resulted in diagnostic sensitivity of 100% and specificity 99%.
Color Doppler US is very important in early detection of vascular complications { as stenosis, thrombosis and pseudo aneurysm} of hepatic artery, portal vein, IVC and hepatic vein especially for early diagnosis of stenosis as severe stenosis can leads to allograft rejection and progress further to the development of all complications as it progress to thrombosis.
Gray scale US and color Doppler has also greater ability for early diagnosis of recurrence of hepatocellular carcinoma and recurrence of liver parenchymaus diseases.
Liver biopsy is usually performed to exclude rejection, recurrent hepatitis, drug effect or other parenchymal disease as a cause of allograft dysfunction.
Color Doppler US (CDUS) is performed to ensure perfect vascular reconstruction after hepatic reperfusion.
For the immediate assessment of general condition and early detection of vascular complications CDUS is becoming the modality of choice to evaluate hepatic hemodynomis.
The use of multidetector CT scanners has led to decreased scanning time and improved overall image quality with thin-section acquisitions.
The thinner images with MDCT provides some benefits, such as reduced volume-averaging artifacts, thereby improving diagnosis of hepatic vascular pathologies. Also multiplanar imaging and CT angiography are much better.
A MDCT angiographic study easily generates over a thousand axial images. Post processing of the dataset offers a variety of advanced three-dimensional models of the hepatic vessels using multi-planar reconstruction (MPR), maximum intensity projection (MIP), and volume rendering (VR) reconstructions.
Although Doppler sonography is considered a primary screening method for detecting postoperative vascular complications, extensive bowel gas and hematomas can sometimes obscure accurate results on sonographic studies. As an alternative noninvasive technique for evaluating the hepatic vasculature, MDCT can provide excellent visualization of filling defects or focal narrowing of hepatic vessels.
MDCT angiography is the best option for confirmation the ultrasonographic suspicion of early and late vascular complications (HAT, main portal vein or inferior vena cava (IVC) stenosis or thrombosis).
The high accuracy, noninvasiveness, fast interpretation with reconstructed images and low cost (less than one-third the cost of conventional angiography) are advantages of MDCTA over DSA.
It is suggested that if any vascular complication is suspected with Doppler ultrasound, MDCTA must be performed for diagnosis, and after that, only if severe/moderate stenosis is detected, the patients must undergo DSA for PTA and/or stent placement therapy due to the high accuracy of the MDCTA examination.
3DCTA provides sufficient information not only on patency or stenosis of smaller vessels but also on other abnormalities in the liver parenchyma, biliary, and extra-hepatic sites, which forms the major decision for the treatment of the detected vascular complication