Should I order CT chest and MRI of the abdomen/pelvis with contrast to rule out vascular invasion from a mass?

CT Chest and MRI Abdomen/Pelvis for Mass Vascular Invasion Assessment: Use Contrast

Both CT chest and MRI of the abdomen/pelvis should be performed WITH intravenous contrast when evaluating for vascular invasion from a mass. 1

Rationale for Contrast-Enhanced Studies

CT Chest with Contrast

• Contrast-enhanced CT is superior for:
  • Defining the relationship between a mass and adjacent structures
  • Assessing mediastinal invasion
  • Distinguishing central obstructing tumor from surrounding atelectasis 1
  • Evaluating the interface between soft tissue masses and adjacent osseous cortex 1

MRI Abdomen/Pelvis with Contrast

• MRI with contrast provides:
  • Superior soft tissue contrast for lesion characterization
  • Better delineation of the relationship between masses and surrounding structures
  • Enhanced ability to detect vascular invasion 1
  • Improved visualization of neurovascular involvement 1

Evidence Supporting Contrast Use

For CT chest:

• The ACR Appropriateness Criteria for Soft-Tissue Masses states that "distinguishing subtle calcification and enhancement may be difficult or impossible without at least some precontrast images" 1
• IV contrast aids in "identification of chest wall invasion by tumor, assessment of extent of mediastinal invasion, evaluation of additional mediastinal and hilar lymph nodes" 1

For MRI abdomen/pelvis:

• MRI has "improved soft-tissue contrast and multiple–image plane capabilities" providing "significant advantages for lesion conspicuity, intrinsic characterization, and local staging" 1
• MRI is particularly valuable for evaluating vascular structures and neurovascular involvement without requiring IV contrast agents 1

Special Considerations for Vascular Invasion Assessment

• Cine MRI techniques can be particularly useful for evaluating sliding motion between masses and adjacent cardiovascular structures, with 94.4% accuracy for determining cardiovascular invasion 2
• CT angiography with 3D reconstruction has been shown to be equivalent to MRI in demonstrating neurovascular involvement 1

Protocol Recommendations

For optimal assessment of vascular invasion:

• CT chest with IV contrast: Single-phase arterial or venous phase depending on the suspected location of invasion 1
• MRI abdomen/pelvis with IV contrast: Multiple sequences including T1-weighted, T2-weighted, and contrast-enhanced T1-weighted images 1

Contraindications to Consider

• For patients with severe renal impairment:
  • Risk of contrast-induced nephropathy with iodinated contrast 3
  • Risk of nephrogenic systemic fibrosis with gadolinium-based contrast 1
• For patients with contrast allergies:
  • Consider premedication protocols or alternative imaging approaches 4

Alternative Approaches When Contrast is Contraindicated

If contrast is absolutely contraindicated:

• Non-contrast CT can still identify calcifications and general mass characteristics 1
• Non-contrast MRI sequences (T1, T2, diffusion-weighted) can provide valuable information about tissue characteristics 1
• Consider ultrasound for superficial masses, though it has limited utility for deep structures 1

In summary, when evaluating for vascular invasion from a mass, both CT chest and MRI abdomen/pelvis should be performed with IV contrast to maximize diagnostic accuracy and provide optimal assessment of the relationship between the mass and surrounding vascular structures.