Imaging Modalities

Benign focal liver lesions, including cysts, hemangiomas, and focal nodular hyperplasia, are common. Annually, many patients worldwide undergo imaging for the work-up of a suspected or known abnormality of the liver. Cross-sectional imaging modalities, such as US, CT, and MR imaging, are used in most centers to assess liver abnormalities. These modalities, often used in various combinations, have fundamental differences in data acquisition and hence differences in the type of physical characteristics of tissues they interrogate. Currently, there is no consensus concerning the optimal strategy for liver imaging. Imaging modalities are often used based on the requests of referring physicians and the availability of equipment and experience of the radiologists. Most centers use US, CT, and CT-guided biopsy; MR imaging is often used as a problem-solving modality. The main goals of imaging are to assess (1) the nature of the lesions, (2) the number and size of liver abnormalities, and (3) the location of abnormalities relative to the vessels. All these aspects influence clinical and surgical decision making. This chapter describes a number of aspects of liver imaging including the current status and recent development of ultrasound, CT, and MR imaging and the role of these imaging modalities in the assessment of benign hepatic abnormalities.