Computed tomography and magnetic resonance imaging

Liver pathologies are common disease processes. Annually, thousands of patients are examined using different imaging modalities for the work-up of suspected or known liver diseases. A primary objective in imaging the liver is to distinguish benign from malignant processes. One should correctly diagnose benign focal liver lesions such as cysts or hemangiomas to avoid unnecessary surgeries. It should be also noted that some other benign lesions such as focal nodular hyperplasias and hepatocellular adenomas may require surgical treatment. However, since the theraupeutical approaches substantially differ, they need to be differentiated from primary or metastatic malignant focal lesions. Regarding the malignant lesions, it is important to early detect primary malignancies such as hepatocellular carcinomas since they may be treated using different approaches such as liver transplantation, chemoembolization, or alcohol ablation. Regarding the metastatic liver lesions, it is important to correctly determine the number and locations of the metastases, since these patients may be effectively treated with different techniques including segmental resection and radiofrequency ablation. Hussain et al. summarizes the main goals of imaging as to assess (1) the number and size of the liver abnormalities, (2) the location of abnormalities relative to liver vessels, (3) the nature of lesions (benign versus malignant), (4) the origin (primary versus secondary) of abnormalities, (5) the liver parenchyma surrounding the lesions [28]. Today, different imaging modalities are used to investigate liver abnormalities. In fact, there is still no consensus concerning the optimal strategy for imaging the liver [27]. Imaging modalities often are applied based upon the availability and the experience of radiologists and gastroenterologists. In this chapter we will try to give information about computed tomography and magnetic resonance imaging and radiologic appearances of various liver pathologies.