What MRI protocol is recommended to evaluate liver lesions?

MRI Protocol for Liver Lesion Evaluation

Order a contrast-enhanced MRI of the abdomen with gadolinium-based contrast agent, including dynamic multiphase imaging (late arterial and portal venous phases at minimum) plus diffusion-weighted imaging (DWI). 1

Essential Protocol Components

Dynamic Contrast Phases (Required)

At least two dynamic imaging phases are mandatory for proper liver lesion characterization: 1

• Late arterial phase (preferred over early arterial, approximately 15-25 seconds post-injection) - captures maximal lesion enhancement 1
• Portal venous phase (approximately 60 seconds post-injection) 1
• Blood equilibrium phase (approximately 120 seconds post-injection) 1

Contrast Agent Selection

For comprehensive lesion characterization, hepatobiliary contrast agents (gadoxetate disodium or gadobenate dimeglumine) are superior to standard extracellular agents: 1

• Gadoxetate disodium (Eovist) is most widely used, with hepatobiliary phase imaging at 20 minutes post-injection (can extend to 120 minutes) 1, 2
• Provides 95-99% accuracy for hemangioma diagnosis, 88-99% accuracy for focal nodular hyperplasia (FNH), and 97% accuracy for hepatocellular carcinoma (HCC) 1
• Hepatobiliary phase allows detection of non-hepatocellular lesions through avid parenchymal enhancement 1

Standard extracellular gadolinium agents remain appropriate when:

• Hepatobiliary phase imaging is not needed
• Dynamic phase quality is paramount (gadoxetate provides less satisfactory arterial phase images) 3
• For hemangioma diagnosis specifically: 93% sensitivity, 99% specificity, 98% accuracy 1

Additional Required Sequences

Include these non-contrast sequences: 4, 5

• T1-weighted imaging (including in-phase and opposed-phase for fat detection) 4, 5
• T2-weighted imaging with fat suppression 4, 5
• Diffusion-weighted imaging (DWI) - critical for lesion detection and characterization 1

DWI combined with hepatobiliary phase correctly classifies lesions as benign versus malignant in 91% of cases and provides exact characterization in 85% of cases. 1

Performance Characteristics

MRI with and without IV contrast establishes definitive diagnosis in 95% of liver lesions, significantly superior to contrast-enhanced CT (71%). 1

• Only 1.5% of MRI patients require additional imaging versus 10% with CT 1
• For adenoma versus FNH differentiation: low signal on hepatobiliary phase is 100% specific, 92% sensitive, and 97% accurate for hepatocellular adenoma 1

Special Considerations

Patients with Chronic Liver Disease

• Dynamic phases (arterial and portal venous) are required per LI-RADS criteria 1
• Hepatobiliary agents particularly valuable for detecting dysplastic nodules and early HCC 4, 5

Patients with Elevated Bilirubin (>3 mg/dL) or Ferritin

• Perform hepatobiliary phase imaging no later than 60 minutes post-injection (rather than standard 20 minutes) as elevated levels reduce hepatic contrast effect 2
• This includes hemodialysis patients with elevated ferritin 2

Suspected Metastases

• Multiphase imaging essential - up to 59% of metastases are isodense to liver on single phase 1
• Gadoxetate hepatobiliary phase improves sensitivity for lesions <1 cm 1
• For hypervascular metastases (neuroendocrine, renal cell, melanoma, thyroid): arterial phase is critical 1

Critical Pitfalls to Avoid

• Never order MRI without contrast for indeterminate lesions - diagnostic yield is insufficient 1
• Do not skip arterial phase imaging - maximal lesion enhancement occurs during late arterial phase 1
• Pseudolesions (focal steatosis, THID) are invisible on DWI - use this to confidently exclude true lesions (negative predictive value = 1) 6
• Well-differentiated HCC may show hepatobiliary phase enhancement - additional clinical information needed for diagnosis 2
• Inflammatory adenomas can mimic FNH on MRI - be aware of this diagnostic pitfall 1