Diagnostic imaging approaches and relationship to hepatobiliary cancer staging and therapy

Diagnostic imaging plays an essential role in management of hepatobiliary tumors. High resolution images provided by computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) allow detection of tumor within the liver. CT arterial portography remains the standard for detection of small lesions in the range of 1.5 cm, but noninvasive techniques such as contrast-enhanced helical CT and MR hold promise for comparable lesion detection. MRI provides lesion characterization for differentiation of benign and malignant tumors. Lesion characterization has been further improved by faster CT and MR techniques that allow imaging in both arterial and portal venous phases for characterization of lesions based on the rate and pattern of enhancement. Functional imaging such as 2-fluoro-2-deoxy-D-glucose-positron-emission tomography (FDG-PET) is increasingly utilized for detection of intrahepatic tumor and extrahepatic disease. Accuracy of FDG-PET for extrahepatic disease is better than conventional imaging and has been shown to change management in a significant number of patients. Imaging is also invaluable for surgical planning. Segmental anatomy is well shown by CT, MRI, and US. CT or MR angiography with newer 3D techniques delineate vascular variants and areas of encasement or occlusion by tumor. Biliary involvement at the hilus may be shown by US and MR cholangiography. Imaging detection of vascular involvement, bile duct extension, and lobar atrophy may alter the surgical approach.