Liver metastases: The role of magnetic resonance imaging

Abstract

The liver is one of the organs most commonly involved in metastatic disease, especially due to its unique vascularization. It’s well known that liver metastases represent the most common hepatic malignant tumors. From a practical point of view, it’s of utmost importance to evaluate the presence of liver metastases when staging oncologic patients, to select the best treatment possible, and finally to predict the overall prognosis. In the past few years, imaging techniques have gained a central role in identifying liver metastases, thanks to ultrasonography, contrast-enhanced computed tomography (CT), and magnetic resonance imaging (MRI). All these techniques, especially CT and MRI, can be considered the non-invasive reference standard techniques for the assessment of liver involvement by metastases. On the other hand, the liver can be affected by different focal lesions, sometimes benign, and sometimes malignant. On these bases, radiologists should face the differential diagnosis between benign and secondary lesions to correctly allocate patients to the best management. Considering the above-mentioned principles, it’s extremely important to underline and refresh the broad spectrum of liver metastases features that can occur in everyday clinical practice. This review aims to summarize the most common imaging features of liver metastases, with a special focus on typical and atypical appearance, by using MRI.

Keywords: Liver metastases, Magnetic resonance imaging, Gadolinium, Gd-EOB-DTPA, Gadoxetate disodium, Liver specific contrast agents, Hepatobiliary contrast agents

Core Tip: To better detect liver metastases, magnetic resonance imaging (MRI) protocol should be correctly performed, using extra-cellular or hepatobiliary contrast agents. Even if conventional non-enhanced techniques can help depict focal liver lesions, contras-enhanced sequences are mandatory, to evaluate their behavior in comparison to the healthy liver parenchyma. These aspects allow to determine liver and hepatic lesions’ vascularization over time and increase radiologists’ diagnostic values. The typical appearance of liver metastases can be easily recognized as hypovascular lesions. However, some primary tumors can produce liver metastases with atypical appearances, such as hypervascular ones, or within calcification, mucin, or other proteins. The multiparametric nature of MRI, combined with the administration of contrast agents, can strongly increase radiologists' confidence in the final diagnosis.