Indeterminate liver lesions on gadoxetic acid-enhanced magnetic resonance imaging of the liver: Case-based radiologic-pathologic review

Different histopathological manifestations of focal liver lesions show varying common and uncommon imaging findings and some pathologies may show similar appearance despite of different histopathology. It is necessary to characterise focal liver lesions accurately as not only benign and malignant lesions are managed differently, but also certain benign lesions have differing management. These lesions are increasingly being detected due to rapid growth of use of cross-sectional imaging as well as improvement in image quality and new imaging techniques. Contrast enhanced magnetic resonance imaging (MRI) is considered the gold standard technique in characterising focal liver lesions. Addition of gadoxetic acid has been shown to significantly increase diagnostic accuracy in the detection and characterization of liver abnormalities. Classic imaging characteristics of common liver lesions, including their behaviour on gadoxetic acid enhanced MRI, have been described in literature over recent years. It is important to be familiar with the typical aspects of these lesions as well as know the uncommon and overlapping imaging features to reach an accurate diagnosis. In this article, we will review the well-described characteristic imaging findings of common and rare focal liver lesions and present several challenging cases encountered in the clinical setting, namely hepatocellular adenoma, focal nodular hyperplasia, hepatic angiomyolipoma, hepatocellular carcinoma, intrahepatic cholangiocarcinoma, neuroendocrine tumours as well as a pleomorphic liposarcoma of the liver.

Focal lesions of the liver: imaging appearances and management

With the increasing use of cross-sectional imaging, the detection of incidental liver lesions has become more common. Accurate and reliable characterisation of these is vital for optimal patient care. Owing to the great improvements in medical imaging technology in recent years, particularly magnetic resonance imaging, it is now possible to characterise a significant proportion of these non-invasively. This is of paramount importance in improving patient safety and reducing costs by avoiding unnecessary biopsies. This article gives a synopsis of the different imaging modalities for liver. It depicts the salient imaging features of the common benign and malignant focal liver lesions on different imaging modalities, with emphasis on magnetic resonance imaging. It demonstrates the pseudolesions, variants, mimics and pitfalls that occur in liver imaging. The tailored magnetic resonance imaging protocols including abbreviated ones, the contrast agents and the pathway for managing incidental liver lesions in the author's institution are covered.

Primary benign liver lesions

Benign focal liver lesions can origin from all kind of liver cells: hepatocytes, mesenchymal and cholangiocellular line. Their features at imaging may sometimes pose difficulties in differential diagnosis with malignant primary and secondary lesions. In particular, the use of MDCT and MRI with extracellular and hepatobiliary Contrast Agents may non invasively help in correct interpretation and definition of hepatocellular or mesenchymal and inflammatory nature, allowing to choose the best treatment option. The peculiarities of main benign liver lesions at US, CT and MRI are described, with special attention to differential diagnosis and diagnostic clues.