Abstract and Introduction
Magnetic resonance imaging (MRI) has emerged as an important imaging modality for the assessment of hepatic masses. Faster sequences now allow high-quality liver imaging with high intrinsic soft-tissue contrast. Automated contrast-detection methods combined with faster sequences allow reproducible capture of the arterial phase, which is essential for the detection and characterization of many hepatic lesions. The lack of ionizing radiation permits routine use of gadolinium-enhanced three-dimensional (3D) fat-suppressed multiphasic imaging with high temporal and spatial resolution.
A comprehensive MR imaging examination in this setting includes T2-weighted and chemical shift T1-weighted imaging, diffusion weighted imaging and gadolinium-enhancement-pattern assessment, characteristic enhancement patterns that can be helpful in the diagnosis of most of these lesions. These patterns can be seen during particular phases of contrast-enhanced imaging and include arterial-phase or delayed-phase enhancement, peripheral washout, ring enhancement, nodule-within-a-nodule enhancement, true central scar, pseudo central scar and pseudo capsule. The combination of findings from different sequences often helps pinpoint the etiology of a liver mass. Familiarity with these enhancement patterns and mass characteristics in various sequences can help in the identification of specific focal lesions of the liver. Sometimes large lesions can be diagnostically challenging as some benign lesions can masquerade as malignant masses. This article focuses on large and geographic hepatic lesions with a primary focus on typical and atypical features of these masses.
MRI is the imaging test of choice for liver-mass characterization, demonstrating similar if not superior performance to CT. The incidence of focal liver lesions parallels growth in imaging utilization. The majority of liver masses arising in noncirrhotic livers are benign. Hemangiomas, focal nodular hyperplasias (FNH), and adenomas (HCA) are the most commonly encountered solid benign lesions.[2–4] The most commonly encountered malignant lesions in noncirrhotic livers are metastases.
Appl Radiol. 2014;43(12):20-28. © 2014 Anderson Publishing, Ltd.