Should an MRI of the liver be performed with or without contrast for a hepatic mass?

From the Guidelines

An MRI of the liver for a hepatic mass should typically be performed both with and without contrast. The preferred contrast agent is gadolinium-based, which helps characterize liver lesions by demonstrating their enhancement patterns during different phases of imaging (arterial, portal venous, and delayed phases) 1. A complete liver MRI protocol should include T1-weighted, T2-weighted, and diffusion-weighted sequences without contrast, followed by dynamic contrast-enhanced sequences. This dual approach provides complementary information: non-contrast images show baseline tissue characteristics and detect fat, iron, or hemorrhage, while contrast-enhanced images reveal vascular patterns and lesion borders that are crucial for differentiating between benign conditions (like hemangiomas, focal nodular hyperplasia, or adenomas) and malignant lesions (like hepatocellular carcinoma or metastases) 1.

Some key points to consider when using MRI for hepatic mass characterization include:

• Gadoxetate-enhanced MRI has an accuracy of 95% to 99% for diagnosis of hemangioma, accuracy of 88% to 99% for the diagnosis of FNH, and accuracy of 97% for diagnosis of HCC in patients with incidentally discovered liver lesions 1.
• Diffusion-weighted imaging (DWI) can be particularly useful in characterizing lesions, especially when contrast cannot be used, and when combined with hepatobiliary phase (HBP) imaging, it allows for correct classification of lesions as benign or malignant in 91% of cases and exact characterization in 85% of cases 1.
• However, contrast should be avoided in patients with severe renal impairment (GFR <30 mL/min) due to the risk of nephrogenic systemic fibrosis, and in pregnant women unless absolutely necessary.

The American College of Radiology (ACR) appropriateness criteria suggest that MRI abdomen without and with IV contrast is usually appropriate for the imaging of an indeterminate >1 cm liver lesion on initial imaging with US in a normal liver with no suspicion or evidence of extrahepatic malignancy or underlying liver disease 1. The use of both non-contrast and contrast-enhanced MRI sequences is recommended for optimal lesion characterization, as it provides a comprehensive evaluation of the liver lesion, helping to guide further management and treatment decisions.

From the Research

MRI of the Liver for Hepatic Mass

For evaluating a hepatic mass, the decision to perform an MRI of the liver with or without contrast is crucial. The use of contrast agents in liver MRI provides valuable information in the evaluation of both chronic liver disease and focal liver lesions 2.

Types of Contrast Agents

There are two main classes of MRI contrast agents available for clinical use: extracellular contrast agents (ECAs) and hepatobiliary agents (HBAs) 2. ECAs have been used for decades and provide excellent dynamic phase information useful in characterizing focal liver lesions. HBAs, such as Gadoxetate, are particularly useful for characterizing lesions with functioning hepatocytes and evaluating the biliary tree 2.

Advantages of Contrast-Enhanced MRI

Contrast-enhanced MRI of the liver offers several advantages, including improved lesion detection and characterization compared to plain MRI 3. The use of contrast agents allows for the quantification of parameters through perfusion MRI or dynamic contrast-enhanced MRI (DCE-MRI), which can help in determining disease or therapeutic response, especially in the oncological setting 3.

Role in Evaluating Focal Hepatic Lesions

Contrast-enhanced MRI has become an important tool in the detection and characterization of focal hepatic lesions, particularly when other investigations like ultrasound and computed tomography are inconclusive 4. The properties of various MRI contrast agents and their role in evaluating focal hepatic lesions highlight the importance of contrast-enhanced MRI in liver imaging 4.

Technical and Methodological Approaches

The applications of MRI for liver imaging continue to grow with the introduction of rapid, high-quality scan techniques and the development of new, tissue-specific contrast agents 5. MRI using T1-weighted, T2-weighted sequences, and serial gadolinium-enhanced gradient echo sequences is effective in detecting and characterizing various hepatic lesions 5.

Pediatric Focal Hepatic Lesions

In the pediatric population, MRI with hepatobiliary contrast agents is beneficial for assessing focal liver lesions, providing valuable information about many encountered lesions 6. The use of gadolinium-based hepatobiliary contrast agents yields beneficial information and makes MRI the preferred imaging modality for complete assessment of focal liver lesions in pediatric patients 6.

Key Points

• Contrast-enhanced MRI provides valuable information in evaluating hepatic masses.
• ECAs and HBAs are the two main classes of contrast agents used.
• Contrast-enhanced MRI offers improved lesion detection and characterization.
• It is particularly useful in the oncological setting and for pediatric focal hepatic lesions.
• The choice of contrast agent depends on the clinical situation and the question to be answered 2, 3, 4, 5, 6.