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Incidental Liver Lesion (ACR)

Guided recommendation from the ACR Incidental Liver Lesion white paper (Gore et al., JACR 2017), for liver lesions found incidentally on CT. Answer the questions; an optional paste box pre-selects what it can.

For lesions incidentally detected on CT, distinguishing benign from potentially malignant. Not for suspected infection/abscess (usually symptomatic) or known hepatic primary under active staging. Management depends on lesion size, imaging features, and the patient's risk category (low vs high).

Encodes the ACR Incidental Liver Lesion algorithm (Fig 1). It covers most, but not all, imaging appearances and clinical scenarios; deviate when the imaging and patient warrant. Recommendations, not standard of care.

Parses size and a few keywords (low/high-risk, cancer, cirrhosis, benign/cyst, suspicious, flash-filling) to pre-select below — always review.

ACR Incidental Liver Lesion algorithm — definitions

Risk category (Table 1)

Low-risk: no known malignancy, no hepatic dysfunction, no hepatic risk factors. (Within low-risk, age >40 y is relatively higher risk.)

High-risk: known malignancy with propensity to metastasize to liver; cirrhosis; and/or hepatic risk factors (hepatitis, NASH, alcoholism, sclerosing cholangitis, primary biliary cirrhosis, choledochal cysts, hemochromatosis / hereditary hepatic conditions, anabolic steroid use).

Benign features⁵

Sharp margin; homogeneous low attenuation (≤20 HU) on noncontrast and/or portal venous phase; or characteristic hemangioma, FNH, focal fatty sparing/deposition, or perfusional change. (With pseudoenhancement a benign cyst may read >20 HU — use discretion.)

Suspicious features⁶

Ill-defined margins, heterogeneous density, mural thickening or nodularity, thick septa, intermediate-to-high attenuation on portal venous phase (>20 HU, absent pseudoenhancement). MRI preferred to evaluate.

"Flash-filling" feature⁷

Uniform hyperenhancement relative to parenchyma on arterial-phase (incl. late arterial/early PV) imaging, when no additional phase characterizes it as a hemangioma or HCC. If other phases let you classify it as benign or suspicious, use those categories instead.

Notes

¹ If imaging is inadequate to ascertain benign vs suspicious features in a ≥1-cm lesion, prompt MRI is advised. ⁴ Follow-up MRI in 3–6 months (may need sooner; CT acceptable if a cancer patient is due for routine CT surveillance). ⁸ Lesions >1.5 cm without benign features should at least undergo prompt MRI; direct biopsy may be appropriate in some scenarios; for FNH-vs-adenoma (esp. >3 cm, subcapsular) MRI with gadoxetate disodium is advised. ⁹ If biopsy is pursued, core biopsy is preferred over FNA.

Gore RM, Pickhardt PJ, Mortele KJ, et al. Management of Incidental Liver Lesions on CT: A White Paper of the ACR Incidental Findings Committee. J Am Coll Radiol 2017;14:1429–1437 (Fig 1).