Gadolinium-based contrast agents (GBCAs) have helped to improve the role of magnetic resonance imaging (MRI) for the diagnosis and treatment of diseases. There are currently nine different commercially available gadolinium-based contrast agents (GBCAs) that can be used for body MRI cases, and which are classifiable according to their structures (cyclic or linear) or biodistribution (extracellular-space agents, target/specific-agents, and blood-pool agents). The aim of this review is to illustrate the commercially available MRI contrast agents, their effect on imaging, and adverse reaction on the body, with the goal to lead to their proper selection in different clinical contexts. When we have to choose between the different GBCAs, we have to consider several factors: (1) safety and clinical impact; (2) biodistribution and diagnostic application; (3) higher relaxivity and better lesion detection; (4) higher stability and lower tissue deposit; (5) gadolinium dose/concentration and lower volume injection; (6) pulse sequences and protocol optimization; (7) higher contrast-to-noise ratio at 3.0 T than at 1.5 T. Knowing the patient\'s clinical information, the relevant GBCAs properties and their effect on body MRI sequences are the key features to perform efficient and high-quality MRI examination.

This letter to the editor is a commentary on a study titled \"Liver metastases: The role of magnetic resonance imaging.\" Exploring a noninvasive imaging evaluation system for the biological behavior of hepatocellular carcinoma (HCC) is the key to achieving precise diagnosis and treatment and improving prognosis. This review summarizes the role of magnetic resonance imaging in the detection and evaluation of liver metastases, describes its main imaging features, and focuses on the added value of the latest imaging tools (such as T1 weighted in phase imaging, T1 weighted out of phase imaging; diffusion-weighted imaging, T2 weighted imaging). In this study, I investigated the necessity and benefits of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid for HCC diagnostic testing and prognostic evaluation.

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.

Focal nodular hyperplasia (FNH) is a solid benign tumor of the liver, predominantly in young women. A correct diagnosis of FNH is essential for making appropriate clinical decisions and avoiding unnecessary liver resection. Herein, we reported that two male cases with FNH, who initially presented with persistent abdominal discomfort, were misdiagnosed with hepatocellular adenoma (HCA) and hepatocellular carcinoma (HCC) on contrast-enhanced magnetic resonance imaging and computed tomography scans, respectively. After surgery, a histological diagnosis of FNH was finally established. In this paper, we also reviewed the knowledge regarding diagnosis and differential diagnosis of FNH on imaging examinations, which are helpful for avoiding misdiagnoses and guiding clinical interventions.

Magnetic resonance imaging is used for evaluating focal liver lesions, hepatic vascular diseases, biliary diseases and diffuse liver diseases in children. MRI examinations take a long time, often requiring sedation or anesthesia in smaller children. This makes it essential to understand the concepts and technique necessary to obtain an optimal examination for answering the clinical question while minimizing the need for sedation/anesthesia. We discuss key concepts including appropriate sequence selection, choice of contrast media, dynamic imaging, phases of contrast enhancement and protocol organization.

OBJECTIVE. The purposes of this article are to review currently available hepatobiliary contrast agents, discuss techniques for optimization of pediatric liver MRI with hepatobiliary contrast agents, and review the imaging features of several pediatric hepatic lesions, focusing on their assessment with hepatobiliary contrast agents. CONCLUSION. MRI is the preferred imaging modality for complete assessment of focal liver lesions in the pediatric population. Imaging with gadolinium-based hepatobiliary contrast agents yields beneficial information about many focal liver lesions encountered in pediatric patients.

Primary Hepatic Epithelioid Haemangioendothelioma (HEHE) and Primary Hepatic Angiosarcoma (PHA) are rare mesenchymal tumours with different malignant potential. Whereas HEHE demonstrates low to intermediate malignant potential, PHA is an aggressive malignancy with poor prognosis. The knowledge of typical imaging features of these lesions may facilitate correct diagnosis; however, the ultimate diagnosis of HEHE and PHA is based on histopathologic examination.
The most typical findings helpful in diagnosing HEHE are: Presence of multiple, confluent nodules located at the liver periphery (in young to middle-aged woman), retraction of the liver capsule, marked hyperintensity on T2-weighted images, \"target-sign\" appearance, progressive centripetal contrast enhancement, and relatively high Apparent Diffusion Coefficient (ADC) values. More than ≥50% of nodules are hyper- or isointense on Hepatobiliary Phase (HBP) images.
The imaging features suggestive of PHA are: Occurrence of metastases (lungs, spleen) at the time of diagnosis, presence of a large dominant mass with smaller satellites, heterogeneity and areas of haemorrhage in a dominant mass, progressive contrast enhancement, slightly elevated ADC values as compared to other malignant liver tumours.

Contrast enhanced MRI of the liver provides valuable information in the evaluation of both chronic liver disease and focal liver lesions. Currently, two classes of MRI contrast agents are available for clinical use, namely the extracellular contrast agent (ECA) and the hepatobiliary agent (HBA). The use of appropriate contrast agents for liver MRI requires knowledge of the clinical situation and question to be answered. ECAs have been used for decades since their introduction into clinical practice and provide excellent dynamic phase information that is useful in characterizing focal liver lesions. In the last decade, HBAs, particularly Gadoxetate, have been found useful for characterizing lesions with functioning hepatocytes and more importantly in evaluating the biliary tree. Gadoxetate, however, provides less satisfactory dynamic phase images compared to ECAs, particularly during the arterial phase. In this perspective article, we will discuss the various intravenous contrast agents used for liver MRI and their ideal utilization.

OBJECTIVE: To describe MRI features of multiple Focal Nodular Hyperplasia (FNHs).
METHODS: 40 consecutive subjects (37 females, mean age, 38.8years) were included. All studies were independently reviewed. This was an observational study to define the radiological features of multifocal FNH.
RESULTS: 130 lesions were evaluated. The majority (88.5%), were peripheral in location. 92.3% lesions were lobulated. Marked enhancement was present in 94.6% lesions. In the portal venous and delayed phase, 46.2% and 47.7% lesions were mildly hyperintense. Central scar was present in 77% lesions.
CONCLUSIONS: Distinctive features included predominant subcapsular location and mild hyperintensity in the delayed phase, seen in nearly 50% of FNHs.

The utilization of advanced imaging modalities play an important role in the detection and differentiation of benign and malignant hepatic lesions. Imaging characteristics of hepatic tumors can sometimes be atypical, often leading to diagnostic challenges. Recent technical improvements in contrast enhanced ultrasound (CEUS), computed tomography (CT), and magnetic resonance imaging (MRI) have helped to better characterize hepatic lesions. For example, contrast agents used in US can now better delineate liver lesions, while the ability to reliably produce multiplanar and 3-D reconstructions through the use of MDCT provides an additional advantage in the context of therapeutic decision making for patients with hepatic lesions. In addition, modern MR that includes the use of biliary excreted contrast material, various post-processing techniques like multiplanar reformation (MPR), as well as volume rendering (VR) allow detailed evaluation of the biliary tract, hepatic vasculature, and better characterization of hepatic tumors. As the imaging technologies available continue to evolve and advance, understanding how to effectively utilize these modalities is key to clinical practice. We herein provide a review of the various hepatic oncologic imaging modalities with a focus on how advancements and novel techniques within the different fields may be utilized in the diagnosis, treatment and management of different benign and malignant hepatic lesions.