Magnetic Resonanance Imaging of the Liver (Including Biliary Contrast Agents)—Part 2: Protocols for Liver Magnetic Resonanance Imaging and Characterization of Common Focal Liver Lesions

Abstract

Magnetic resonance imaging (MRI) is a fundamental tool for the noninvasive evaluation of liver pathologies. The anatomical position, the mobility with respiration, and the peculiar hemodynamics of the liver present several issues that have taken advantage from technological advances in MRI technology in the last decade, in particular regarding hardware, software, and contrast media (CM). We provided an overview of these topics in the first part of the review. MRI pulse sequences of clinical use in liver imaging can be divided into (1) T2-weighted sequences, for detection and characterization of focal and diffuse lesions without contrast, (2) T1-weighted sequences, with or without contrast injection, for further lesion characterization, and (3) additional techniques, such as diffusion-weighted imaging (DWI) and magnetic resonance cholangiopancreatography (MRCP). Most sequences have different names and abbreviations, and the reader is invited to find the respective commercial name specific for each vendor in appropriate references.1 The use of CM adds information on function and vascularity of liver parenchyma and focal lesions. The optimization of the technique for postcontrast studies and the basic concepts for characterization of focal liver lesions are briefly discussed in the following sections. MRI provides several advanced techniques for quantitative evaluation of diffuse liver disease. The complexity of these techniques is beyond the scope of this review, and only a brief description on magnetic resonance elastography (MRE), fat and iron quantification would be provided. At the end of our overview, we would discuss strategies to build basic liver protocols.