Table 1.

Explanation of Each Imaging Feature for LR-M and Category.

Feature/Category	Definition
CEUS LI-RADS
Rim APHE	Arterial phase enhancement is most pronounced in observation periphery
Early washout	Whole or partial hypoenhancement relative to liver occurs within 60 s after injection of the contrast agent.
Marked washout	Nodule becomes markedly hypoenhanced (appears as black hole) within 2 min (otherwise defined as mild)
CT/MR LI-RADS
Rim APHE	Arterial phase enhancement that is most pronounced in observation periphery
Peripheral washout	An apparent washout that is most pronounced in observation periphery
Delayed central enhancement	Central area of progressive postarterial phase enhancement
Targetoid restriction	Concentric pattern on DWI characterized by restricted diffusion in observation periphery with less restricted diffusion in observation center
Targetoid TP or HBP appearance	Concentric pattern in TP or HBP characterized by moderate-to-marked hypointensity in observation periphery with milder hypointensity in center
Categories of LI-RADS
LR-1	100% certainty that the finding is benign
LR-2	Probably benign
LR-3	Intermediate malignancy probability
LR-4	Probably HCC
LR-5	Definitely HCC
LR-M	Probably or definitely malignant but not HCC specific
LR-TIV	Definite tumor in vein

CEUS, contrast enhanced ultrasound; LI-RADS, Liver Imaging Reporting and Data System; APHE, arterial phase hyperenhancement; TP, transitional phase; HBP, hepatobiliary phase.