Apply only after confirming the high-risk population and adequate multiphase technique. Follow the precedence branches before the major-feature table; LR-TIV indicates malignancy but not necessarily HCC.
{
"applicability": {
"use_for": [
"cirrhosis",
"chronic_hepatitis_B",
"current_or_prior_HCC"
],
"do_not_use_for": [
"patient_under_18",
"no_HCC_risk_factor",
"congenital_hepatic_fibrosis",
"cirrhosis_due_to_hereditary_hemorrhagic_telangiectasia",
"cirrhosis_due_to_Budd_Chiari_syndrome",
"cirrhosis_due_to_chronic_portal_vein_occlusion",
"cirrhosis_due_to_cardiac_congestion",
"diffuse_nodular_regenerative_hyperplasia"
],
"technique": "Multiphase CT or MRI is required to characterize all major features; do not force a formal category from a single-phase examination."
},
"precedence": [
{
"outcome_code": "LR-NC",
"when": "Key phases are omitted or degraded so the observation cannot be meaningfully separated across benign and malignant category ranges."
},
{
"outcome_code": "LR-TIV",
"when": "Unequivocal enhancing soft tissue is present in a vein; classify a contiguous parenchymal observation separately when present."
},
{
"outcome_code": "LR-1",
"when": "The observation is definitely benign."
},
{
"outcome_code": "LR-2",
"when": "The observation is probably benign."
},
{
"outcome_code": "LR-M",
"when": "The observation is probably or definitely malignant but lacks HCC-specific features, including a targetoid mass."
},
{
"action": "apply_diagnostic_table",
"when": "None of the preceding branches applies."
}
],
"axes": {
"APHE": [
"none",
"nonrim"
],
"diameter_mm": [
"<10",
"10-19",
"<20",
">=20"
],
"additional_major_features": [
"nonperipheral_washout",
"enhancing_capsule",
"threshold_growth"
]
},
"major_feature_rules": {
"threshold_growth": ">=50% increase in observation diameter in <=6 months; once met, threshold-growth positivity carries forward on later examinations.",
"uncertainty": "If unsure whether a major feature is present, characterize it as absent."
},
"cells": [
{
"APHE": "none",
"diameter_mm": "<20",
"additional_major_feature_count": 0,
"outcome_code": "LR-3"
},
{
"APHE": "none",
"diameter_mm": "<20",
"additional_major_feature_count": 1,
"outcome_code": "LR-3"
},
{
"APHE": "none",
"diameter_mm": "<20",
"additional_major_feature_count": ">=2",
"outcome_code": "LR-4"
},
{
"APHE": "none",
"diameter_mm": ">=20",
"additional_major_feature_count": 0,
"outcome_code": "LR-3"
},
{
"APHE": "none",
"diameter_mm": ">=20",
"additional_major_feature_count": 1,
"outcome_code": "LR-4"
},
{
"APHE": "none",
"diameter_mm": ">=20",
"additional_major_feature_count": ">=2",
"outcome_code": "LR-4"
},
{
"APHE": "nonrim",
"diameter_mm": "<10",
"additional_major_feature_count": 0,
"outcome_code": "LR-3"
},
{
"APHE": "nonrim",
"diameter_mm": "<10",
"additional_major_feature_count": 1,
"outcome_code": "LR-4"
},
{
"APHE": "nonrim",
"diameter_mm": "<10",
"additional_major_feature_count": ">=2",
"outcome_code": "LR-4"
},
{
"APHE": "nonrim",
"diameter_mm": "10-19",
"additional_major_feature_count": 0,
"outcome_code": "LR-3"
},
{
"APHE": "nonrim",
"diameter_mm": "10-19",
"additional_major_feature_count": 1,
"only_feature": "enhancing_capsule",
"outcome_code": "LR-4"
},
{
"APHE": "nonrim",
"diameter_mm": "10-19",
"additional_major_feature_count": 1,
"feature": "nonperipheral_washout_or_threshold_growth",
"outcome_code": "LR-5"
},
{
"APHE": "nonrim",
"diameter_mm": "10-19",
"additional_major_feature_count": ">=2",
"outcome_code": "LR-5"
},
{
"APHE": "nonrim",
"diameter_mm": ">=20",
"additional_major_feature_count": 0,
"outcome_code": "LR-4"
},
{
"APHE": "nonrim",
"diameter_mm": ">=20",
"additional_major_feature_count": 1,
"outcome_code": "LR-5"
},
{
"APHE": "nonrim",
"diameter_mm": ">=20",
"additional_major_feature_count": ">=2",
"outcome_code": "LR-5"
}
],
"LR_M_features": {
"targetoid": [
"rim_APHE",
"peripheral_washout",
"delayed_central_enhancement",
"targetoid_diffusion_restriction",
"targetoid_transitional_or_hepatobiliary_phase_appearance"
],
"nontargetoid": [
"infiltrative_appearance",
"marked_diffusion_restriction",
"necrosis_or_severe_ischemia",
"other_feature_suggesting_non_HCC_malignancy"
]
},
"ancillary_features": {
"use": "optional",
"effect": "May adjust the category by one level when they favor malignancy or benignity.",
"limits": [
"never_upgrade_to_LR-5",
"do_not_change_category_when_benign_and_malignant_ancillary_features_conflict"
]
},
"tie_breaking": "When uncertain between categories, choose the category that reflects lower certainty; never preserve LR-1 or LR-5 certainty by assumption.",
"reporting": {
"LR_NC": "State the technical limitation or artifact and whether repeat same-modality imaging or a different modality/contrast agent is needed.",
"LR_TIV": "Report involved vessel(s), the most likely etiology when possible, and the presence, size, and category of any contiguous parenchymal mass."
},
"categories": [
"LR-NC",
"LR-1",
"LR-2",
"LR-3",
"LR-4",
"LR-5",
"LR-M",
"LR-TIV"
],
"source_locator": "ACR CT/MRI LI-RADS v2018 Core, diagnostic algorithm and diagnostic table pp 7-8, ancillary/tie-breaking rules pp 9-10, management p 14; ACR LI-RADS FAQs 001-008, 022-048, and 063-077."
}