Diffuse liver disease: strategies for hepatic CT and MR imaging

The liver plays several complex but essential roles in the metabolism of amino acids, carbohydrates, and lipids, as well as synthesis of proteins. The basic pathophysiology of diffuse parenchymal hepatic diseases usually represents a failure in one of these metabolic pathways. Specific parenchymal diseases can be categorized as storage, vascular, and inflammatory diseases. Cross-sectional hepatic imaging techniques, specifically multidetector computed tomography (CT) and magnetic resonance (MR) imaging, have roles in evaluation of diffuse liver disease. The prominent role of multidetector CT is primarily defined by its excellent morphologic visualization capabilities, in particular of diffuse or focal intrahepatic lesions as well as of anatomic relationships between the liver and adjacent organs. The variety of available multidetector CT scanners covers a huge spectrum of detector configurations ranging from equally sized and equally spaced detector arrays to asymmetric detector configurations, resulting in imaging protocols with unique parameters for almost each multidetector CT system. In addition to 64-detector row imaging, hepatic multidetector CT can be performed with emerging techniques such as dual-energy CT. Hepatic MR imaging has been proved to be a comprehensive modality for assessing the morphology and functional characteristics of the liver. Concurrent technical improvements as well as implementation of advanced imaging sequence designs permit high-quality examination of the liver with T1-, T2-, and diffusion-weighted pulse sequences. Three basic demands remain if MR imaging is chosen for hepatic imaging: to improve parenchymal contrast, to suppress respiratory motion, and to ensure complete anatomic coverage. Supplemental material available at http://radiographics.rsna.org/content/29/6/1591/suppl/DC1.