Standardized risk categorization of focal liver lesions in high-risk patients for hepatocellular carcinoma using CT/MRI.
Text summary of the rules this calculator applies, generated from the same definitions the calculation uses.
LI-RADS v2018 applies to hepatic observations in patients at established risk for hepatocellular carcinoma (HCC): cirrhosis, chronic hepatitis B, or prior HCC.
This calculator implements the "LI-RADS Core" (main diagnostic algorithm, including the optional ancillary-features step); it does not replace the full ACR LI-RADS manual for special cases (treated lesions, additional ancillary findings not listed here, etc.).
| Variable | Definition | Possible values | Unit |
|---|---|---|---|
| Definite tumor in vein (macrovascular tumor invasion, "LR-TIV")? | — | Yes · No | Yes / No |
| Continuity of the tumor in vein with the hepatic lesion: | — | Continuous with an LR-5 lesion · Continuous with an LR-M lesion · Continuity cannot be specified | Categorical |
| Features of malignancy not specific to HCC ("LR-M": rim APHE, marked diffusion restriction in a rim, marked necrosis/ischemia, infiltrative morphology)? | — | Yes · No | Yes / No |
| Observation size | — | < 10 mm · 10-19 mm · ≥ 20 mm | mm |
| Nonrim arterial phase hyperenhancement (APHE) | — | Yes · No | Yes / No |
| Additional features (check all that apply) — several can be selected | — | Nonperipheral "washout" · Enhancing capsule · Threshold growth (≥ 50% in ≤ 6 months) | Categorical |
| Step 2 (optional): Ancillary features (AFs) — several can be selected | Ancillary features (AFs) may be used at radiologist discretion to improve detection, increase diagnostic confidence, or adjust the numeric category (LR-1 to LR-5). If unsure about the presence of an ancillary feature, characterize it as absent. | Favoring malignancy in general (not HCC specific) · Favoring HCC in particular · Favoring benignity | Categorical |
LR-TIV and LR-M take priority over the numeric category: if there is tumor in vein or non-HCC-specific malignant features, that category replaces the LR-1 to 5 category computed from size/APHE/features.
| Additional features | < 10 mm | 10-19 mm | ≥ 20 mm |
|---|---|---|---|
| None | LR-3 | LR-3 | LR-3 |
| 1 feature (any) | LR-3 | LR-3 | LR-4 |
| 2 features (any) | LR-4 | LR-4 | LR-4 |
| Nonperipheral "washout" + Enhancing capsule + Threshold growth (≥ 50% in ≤ 6 months) | LR-4 | LR-4 | LR-4 |
| Additional features | < 10 mm | 10-19 mm | ≥ 20 mm |
|---|---|---|---|
| None | LR-3 | LR-3 | LR-4 |
| Nonperipheral "washout" | LR-4 | LR-5 | LR-5 |
| Enhancing capsule | LR-4 | LR-4 | LR-5 |
| Threshold growth (≥ 50% in ≤ 6 months) | LR-4 | LR-5 | LR-5 |
| 2 features (any) | LR-4 | LR-5 | LR-5 |
| Nonperipheral "washout" + Enhancing capsule + Threshold growth (≥ 50% in ≤ 6 months) | LR-4 | LR-5 | LR-5 |
The numeric category combines lesion size, presence of nonrim arterial phase hyperenhancement (APHE), and the number and type of additional major features (nonperipheral washout, enhancing capsule, threshold growth). For 10-19 mm observations with APHE: 0 additional features = LR-3; exactly 1 feature = LR-4 if it is enhancing capsule, but LR-5 if it is nonperipheral washout or threshold growth (unlike washout or growth, capsule alone does not reach LR-5 at this size); ≥2 features = LR-5. For observations ≥20 mm with APHE, any additional feature (one or more) already corresponds to LR-5.
Ancillary features (AFs) may be used at radiologist discretion to improve detection, increase diagnostic confidence, or adjust the numeric category (LR-1 to LR-5). If unsure about the presence of an ancillary feature, characterize it as absent.
| Base category | Only AFs favoring malignancy | Only AFs favoring benignity | AFs of both kinds |
|---|---|---|---|
| LR-1 | LR-2 | LR-1 | LR-1 |
| LR-2 | LR-3 | LR-1 | LR-2 |
| LR-3 | LR-4 | LR-2 | LR-3 |
| LR-4 | LR-4 | LR-3 | LR-4 |
| LR-5 | LR-5 | LR-4 | LR-5 |
Adjustment rule: ≥1 AF favoring malignancy upgrades the category by 1 level, but never above LR-4 (AFs alone never reach LR-5). ≥1 AF favoring benignity downgrades the category by 1 level. If AFs of both types are present, the category is not adjusted. This adjustment does not apply to the LR-TIV or LR-M categories.
| Category | Meaning |
|---|---|
| LR-1 | Definitely benign |
| LR-2 | Probably benign |
| LR-3 | Intermediate probability of HCC |
| LR-4 | Probably HCC |
| LR-5 | Definitely HCC |
| LR-M | Probably or definitely malignant, not HCC-specific |
| LR-TIV | Tumor in vein (macrovascular tumor invasion) |