LI-RADS Liver Imaging Reporting and Data System, CT/MRI v2018

{
  "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."
}