Definition:

Presence of tumor in vein lumen.

LI-RADS Categorization

• Observations thought to definitely represent tumor in vein should be categorized LR-5V
• Observations thought to probably represent tumor in vein should be categorized as LR-3, LR-4, or LR-5 based on Table
• Observations that are indeterminate for tumor in vein should be categorized as LR-3, LR-4, or LR-5 based on Table

Synonyms:

• Vascular invasion, Tumor thrombus
• The term tumor in vein is preferred over the term tumor thrombus.
• Rationale: the pathological spectrum ranges from thrombus with scant tumor cells to solid tumor with scant thrombus.

Characteristic imaging features:

• Definite enhancing soft tissue in vein.

Potential pitfalls and challenges:

• Parenchymal mass may or may not be demonstrated at imaging.
• While not diagnostic of tumor in vein, features that may alert radiologist to diagnosis include:
  • Occluded vein with any of the following: expanded lumen, ill-defined walls, restricted diffusion, or contiguity with LR-5 observation
  • Obscured, partially visualized vein
  • Heterogeneous enhancement of vein not attributable to mixing artifact 

• By comparison, non-tumoral bland thrombus does not enhance and usually does not expand lumen

• Tumor in vein may be more difficult to identify with gadoxetate disodium (HBA) due to more rapid venous clearance of contrast in the portal venous, delayed, and transitional phases with resulting decreased vein to tumor contrast.