Liver observation — CT / MRI (LI-RADS)

CTMRIACR LI-RADS v2018 (CT/MRI)

A liver observation in a patient at high risk for HCC, on multiphase CT or MRI.

Applies to

Cirrhosis
Chronic hepatitis B
Current or prior HCC

Does not apply to

Patients without HCC risk factors — LI-RADS does not apply
Cirrhosis due to congenital hepatic fibrosis or vascular disorders
Patients under 18 years

What to report

Tap an item to check it off while dictating.

1.Size and location
Maximum diameter in mm and segment. Size drives the diagnostic category.
2.Arterial phase hyperenhancement
Nonrim APHE is a major feature. Ensure late-arterial phase timing.
Pitfall: Rim APHE points toward LR-M rather than a major feature.
3.Nonperipheral washout
Assessed in the portal-venous or delayed phase.
4.Enhancing capsule
A smooth enhancing rim in the portal-venous or delayed phase.
5.Threshold growth
≥50% increase in diameter within ≤6 months.
6.LR-M / TIV features
Targetoid morphology (rim APHE, peripheral washout, targetoid restriction) suggests LR-M; assess veins for tumor in vein (LR-TIV).

Scores & calculators

LI-RADS diagnostic category

ACR LI-RADS v2018 (CT/MRI)

Diagnostic category for an untreated liver observation in a patient at high risk for HCC (cirrhosis, chronic hepatitis B, or prior HCC).

Category-defining features

Arterial phase hyperenhancement (APHE)

None (or rim/peripheral only)Nonrim APHE present

Observation size

Nonperipheral washout

AbsentPresent

Enhancing capsule

AbsentPresent

Threshold growth (≥50% in ≤6 months)

AbsentPresent

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Sources

CT/MRI LI-RADS v2018 — American College of Radiology (2018)

Content review: Content pending clinical review · 2026-07-09

Educational reference for trained clinicians. Verify every result against the cited original guideline before use. Not a substitute for clinical judgment or medical advice.