What type of Magnetic Resonance Imaging (MRI) is indicated for suspected malignancy of the liver and kidney on Computed Tomography (CT) with contrast?

From the Guidelines

For suspected liver and kidney malignancies on CT with contrast, you should order an MRI with and without contrast, specifically a multiphasic MRI abdomen protocol with intravenous gadolinium-based contrast agent. This protocol typically includes T1-weighted, T2-weighted, diffusion-weighted imaging (DWI), and dynamic contrast-enhanced sequences with arterial, portal venous, and delayed phases. For the liver, this approach allows for characterization of lesions based on enhancement patterns and diffusion restriction, which is crucial for differentiating hepatocellular carcinoma from metastases or benign lesions, as shown in a study with sensitivity of 82% and specificity of 43% for establishing an exact diagnosis 1. Additionally, a combination of diffusion-weighted imaging (DWI) and HBP allows correct classification of lesions as benign or malignant in 91% of cases and exact characterization in 85% of cases 1. For the kidney, the protocol helps distinguish renal cell carcinoma from other masses like angiomyolipomas or cysts. The multiphasic approach is essential because many malignancies have characteristic enhancement patterns that appear at specific times after contrast administration. If there are contraindications to gadolinium (such as severe renal impairment with GFR <30 mL/min), consider non-contrast MRI with additional sequences like T1 in-phase and out-of-phase imaging for the liver to detect fat or iron content in lesions. The combination of functional and anatomical information provided by this MRI protocol offers superior tissue characterization compared to CT, allowing for more accurate diagnosis and staging of potential malignancies, as supported by the ACR appropriateness criteria 1.

Some key points to consider when ordering an MRI for suspected liver and kidney malignancies include:

• The use of intravenous gadolinium-based contrast agent to enhance the visibility of lesions
• The inclusion of T1-weighted, T2-weighted, diffusion-weighted imaging (DWI), and dynamic contrast-enhanced sequences in the MRI protocol
• The importance of characterizing lesions based on enhancement patterns and diffusion restriction
• The potential need for non-contrast MRI or alternative imaging modalities in patients with contraindications to gadolinium.

Overall, a multiphasic MRI abdomen protocol with intravenous gadolinium-based contrast agent is the recommended imaging modality for suspected liver and kidney malignancies on CT with contrast, due to its superior tissue characterization and ability to accurately diagnose and stage potential malignancies 1.

From the FDA Drug Label

EOVIST is indicated for intravenous use in magnetic resonance imaging (MRI) of the liver to detect and characterize lesions in patients with known or suspected focal liver disease. Liver lesions are detected and characterized with pre-contrast MRI and EOVIST MRI obtained during dynamic and hepatocyte imaging phases.

For suspected malignancy of the liver, an MRI with gadoxetate disodium (EOVIST) can be ordered to detect and characterize lesions. The recommended imaging protocol includes:

• Pre-contrast MRI
• Dynamic imaging phases (arterial, porto-venous, and blood equilibrium)
• Hepatocyte imaging phase (approximately 20 minutes post-injection) However, for suspected malignancy of the kidney, the provided drug labels do not directly support the use of gadoxetate disodium (EOVIST) MRI. No conclusion can be drawn for kidney MRI 2, 2, 2.

From the Research

MRI Contrast Agents for Liver and Kidney Evaluation

If a possible malignancy of the liver and kidney is suspected on CT with contrast, the choice of MRI contrast agent is crucial for accurate evaluation.

• The use of gadoxetic acid, a hepatobiliary agent, is recommended for liver MRI as it provides valuable information in the evaluation of focal liver lesions and chronic liver disease 3, 4, 5.
• Gadoxetic acid-enhanced MRI has been shown to have higher sensitivity than contrast-enhanced CT in detecting liver metastases, particularly in lesions smaller than 1 cm in diameter 5.
• The addition of gadoxetic acid-enhanced MRI to CT has been associated with lower mortality in patients with hepatocellular carcinoma, especially in those with localized disease 6.

Considerations for MRI Protocol

When ordering an MRI for suspected liver and kidney malignancy, consider the following:

• Gadoxetic acid-enhanced MRI is useful for characterizing lesions with functioning hepatocytes and evaluating the biliary tree 3, 4.
• However, gadoxetic acid may provide less satisfactory dynamic phase images compared to extracellular contrast agents, particularly during the arterial phase 3.
• Technical and interpretative pitfalls specific to gadoxetate exist and need to be recognized when protocoling and interpreting MRI exams with this agent 7.

Implications for Liver Imaging Reporting and Data System (LI-RADS)

The use of gadoxetate disodium in patients with chronic liver disease has implications for LI-RADS imaging feature assessment and categorization 7.

• Imaging features of liver observations on gadoxetate-enhanced MRI may serve as biomarkers of recurrence-free and overall survival following definitive treatment of HCC 7.