الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
CT perfusion plays an important role in assessment of various benign and malignant hepatic focal lesions. CTP is a noninvasive method showing hemodynamic changes in living tissue and has been used in evaluation of liver diseases. As CTP is a relatively simple imaging technique, it could be integrated into the current CT protocols, being an in vivo marker of tumor-related vascularization. In cirrhosis portal venous flow decreases which is counteracted by increase in hepatic arterial flow .this lead to increase hepatic arterial perfusion parameters. These changes tend to increase significantly with progression of the disease. CTP can differentiate hemangioma from HCC by comparing HAP in center and edge of the lesion as it is higher in the edge of hemangioma more than in its center. As HCC is associated with a progression toward increasing arterial supply so CTP parameters are higher in HCC comparing to background liver. CTP can provide quantitative information about arterial perfusion in early HCCs. It can aid in detection of dysplastic nodules in cirrhotic liver before being frank HCC which may be critical to patient outcome. 3D perfusion images for the evaluation of HCCs could be generated using 256-slice MDCT perfusion of the entire tumor can usually be examined three dimensionally, and perfusion of the liver parenchyma can be measured over an extensive range. CTP shows increase arterial perfusion in patients with liver metastases. CTP can help in evaluation of therapeutic efficacy as it is effective technique for quantification of tumour vascularity and angiogenesis. The response to TACE may be evaluated by comparing the difference in perfusion parameters pre- and post-treatment for assessment of tumour viability. CTP is performed also for patients at the end of each treatment cycle of chemotherapy to evaluate the response to the chemotherapy and severity of liver impairment. CTP of the Liver during Selective Hepatic Arteriography for estimation of the hepatic arterial blood flow of the liver independently of portal blood flow, by means of selective contrast injection into the HA via an angiographic catheter. After liver transplantation .It is very important to evaluate non-invasive liver perfusion CTP can monitor the tendency of hemodynamic changes in PV and HA, contributing to the early diagnosis of blood vessel complications after transplantation. Radiation dose may be a limitation to the frequent use of CTP. However as CT technology evolves, the radiation exposure is reduced because of decreased scanning time and improved detector sensitivity. Liver CTP imaging has opened up a new area for its clinical application. One single CT scan can provide both morphologic and functional information, so that clinicians can detect the disease before morphological changes and evaluate the effect of treatment. MDCT has a high time and spatial resolution for the measurement of perfusion. It is an effective non-invasive method for assessment of tumor vascularity and follow up after intervention, chemotherapy and liver transplantation. CTP imaging is safe, reproducible, and easy to operate.