5. To explore the clinical pathological characteristics of HCC patients which may affect the accuracy of 18F-FECH PET in diagnosis of HCC, and to determine under which conditions the patients are suitable for 18F-FECH PET scan and to explore whether the liver disease itself, such as cirrhosis would affect the diagnostic efficacy of 18F-FECH PET. The characteristics include tumor size (diameter ≤ or > 3cm), number of lesions, Edmondson grade (including immuno-histochemistry), tumor thrombus in portal vein, extra-hepatic metastasis, clinical stage; patients' age, sex, history of disease (including chronic hepatitis, cirrhosis, metabolic disease such as hepatolenticular degeneration, genetic diseases such as Gaucher disease and Niemann-Peak disease), liver function (Child-Pugh grade) and coagulation function.