الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Liver malignancies are classified into primary & secondary. Metastases are the most common malignant tumours affecting the liver occurring 20 times more than primary carcinomas. Colo-rectal, gastric, pancreatic, lung & breast contribute to 90% of malignancies that send metastases to liver. Primary liver tumours are from epithelial origin (Hepatocellular carcinoma & cholangio carcinoma).
Hepatocellular carcinoma (HCC) is the 5h most common cancer world wide & responsible for up to 1 million deaths annually.
Although U/S had the best diagnostic performance in depicting HCC on patient by patient bases, CT & MRI have nearly equivalent diagnostic performance on lesion by lesion basis. Small tumour nodules were the most common cause of missed HCC with all tests.
Liver is one of the most common organs for metastasis, yet its diagnosis may be missed by CT & MR image so, for evaluation of liver metastasis PET/CT appears to be the technique of choice.
The rapid advances in imaging technology provides PET-FDG as a radiopharmaceutical that provides the capability for imaging tumour metabolism but lacking anatomical delineation was a great obstacle.
PET/CT fusion images have the potential to provide information anatomically & metabolically so provides a better map for active tumours whether primaries, secondaries or recurrence after resection.
PET/CT is superior to PET and CT alone, and/or magnetic resonance imaging (MRI), in the diagnosis and treatment of various primary or metastatic cancers. Thus, PET/CT is a more accurate test than either of its individual components.
PET/CT has advantage over other imaging method, it can differentiate benign from malignant lesions, staging, and restaging tumour, detect functional changes before there is any changes in clinical or radiological size of mass, better in identify cancer that has spread, making up treatment plane and monitoring tumour response, detect tumour recurrence early and distinguish viable metabolically active tissue from scars.
Currently, positron emission tomography/computer tomography (PET/CT) are more and more widely available and their application with 18F-fluorodeoxyglucose (18F-FDG) in oncology has become one of the standard imaging modalities in diagnosing and staging of tumours, and monitoring the therapeutic efficacy in hepatic malignancies. It is more sensitive and specific than PET, with a lower false-positive and false-negative rate.
Whole body positron emission tomography with (180F-Flurodeoxy-glucose (FDG) in combination with CT scanning (PET/CT) represents one of the most sensitive imaging modalities for early detection of colorectal cancer, recurrence or hepatic metastases and extra hepatic tumour manifestation.
PET/CT is particularly indicated for restaging in patients with suspected recurrent and metastatic disease.
PET and PET/CT is very important in patients with unexplained high levels of tumor markers.
18F-FDG PET/CT appears to be a reliable technique for evaluating the veins of the portal system thrombus, and can be helpful in discriminating between benign and malignant portal vein thrombi.
Limitation of PET/CT includes the following:
Cost.
Motion artefact, CT truncation artifacts and attenuation correction artifact.
CT scan limitations and radiation exposure,
Highly trained personnel to generate the radiopharmaceuticals used for PET imaging.