Positron emission tomography/computer tomography: challenge to conventional imaging modalities in evaluating primary and metastatic liver malignancies.

Computer tomography (CT) and magnetic resonance imaging (MRI), as conventional imaging modalities, are the preferred methodology for tumor, nodal and systemic metastasis (TNM) staging. However, all the noninvasive techniques in current use are not sufficiently able to identify primary tumors and even unable to define the extent of metastatic spread. In addition, relying exclusively on macromorphological characteristics to make a conclusion runs the risk of misdiagnosis due mainly to the intrinsic limitations of the imaging modalities themselves. Solely based on the macromorphological characteristics of cancer, one cannot give an appropriate assessment of the biological characteristics of tumors. Currently, positron emission tomography/computer tomography (PET/CT) are more and more widely available and their application with (18)F-fluorodeoxyglucose ((18)F-FDG) in oncology has become one of the standard imaging modalities in diagnosing and staging of tumors, and monitoring the therapeutic efficacy in hepatic malignancies. Recently, investigators have measured glucose utilization in liver tumors using (18)F-FDG, PET and PET/CT in order to establish diagnosis of tumors, assess their biologic characteristics and predict therapeutic effects on hepatic malignancies. PET/CT with (18)F-FDG as a radiotracer may further enhance the hepatic malignancy diagnostic algorithm by accurate diagnosis, staging, restaging and evaluating its biological characteristics, which can benefit the patients suffering from hepatic metastases, hepatocellular carcinoma and cholangiocarcinoma.