On multiphasic CT, a 4 cm hepatic lesion in a 50-year-old man with hepatitis B cirrhosis shows arterial phase hyperenhancement (APHE) and portal venous phase washout appearance. LI-RADS categorization of this observation is:

• A LI-RADS 3 (intermediate probability of HCC)
• B LI-RADS 4 (probably HCC)
• C LI-RADS 5 (definitely HCC — ≥95% probability) ✓
• D LI-RADS M (probably malignant but not HCC-specific)

Explanation

LI-RADS 5 (definite HCC) requires APHE plus one additional major feature in a ≥20 mm observation, or APHE plus two additional major features in a 10–19 mm observation. Major features: washout appearance, enhancing capsule, threshold growth (≥50% increase in ≤6 months). This 4 cm lesion with both APHE and washout appearance meets criteria for LR-5. The APHE + washout combination reflects the unique hepatocellular vascular supply (arterial via tumor neovascularization, with loss of portal supply in HCC). LI-RADS M applies when features (e.g., targetoid enhancement) suggest non-HCC malignancy.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.