Table 2. Liver imaging reporting and data system (LI-RADS) for HCC. Adapted from the American College of Radiology.24,40.

LI-RADS class	Description	Comment
1	Benign	Cyst, hemangioma, perfusion alteration (e.g., arterioportal shunt), hepatic fat deposition/sparing, hypertrophic pseudomass, confluent fibrosis or focal scar, etc. OR It disappears without treatment
2	Probably benign	Suggestive of a benign entity based on experience, as above OR Distinctive nodule without malignant features* OR Stable imaging features for ≥2 years OR Probable disappearance in the absence of treatment
3	Intermediate probability of being benign	<2 cm: Mass-like configuration with arterial-phase hyperenhancement and no additional major features# OR Mass-like configuration with arterial phase hypoenhancement and ≤1 additional major feature# ≥2 cm: Mass-like configuration with arterial phase hypoenhancement and no additional major features# Any size: Non-mass-like configuration and neither LR-1 nor LR-2 OR Cannot be categorized as LR-1, LR-2, LR-4, or LR-5 OR Meets criteria for LR-4 or LR-5, with stability for ≥2 years
4	Probably HCC	Category A (<2 cm): Mass-like configuration with arterial phase hyperenhancement and 1 additional major feature# OR Mass-like configuration with arterial phase iso- or hypoenhancement and 2 additional major features# OR Probable tumor within lumen of vein Category B (≥2 cm): Mass-like configuration with arterial phase hyperenhancement and no additional major features# OR Mass-like configuration with arterial phase iso- or hypoenhancement and 1 or 2 additional major features# OR Probable tumor within lumen of vein
5	HCC	Category A (≥1 cm but <2 cm): Mass-like configuration with arterial phase hyperenhancement and 2 additional major features# OR Definite tumor within lumen of vein Category B (≥2 cm): Mass-like configuration with arterial phase hyperenhancement and 1 or 2 additional major features# OR Definite tumor within lumen of vein

^*Solid nodule <20 mm distinctive in imaging appearance compared to background nodules AND with no major feature of HCC, and no ancillary feature of malignancy

^#Additional major features; portal venous phase or later phase hypoenhancement, increase in diameter of at least 1 cm within 1 year

Abbreviations: HCC, hepatocellular carcinoma; LR, LI-RADS.