Liver lesion evaluation in patients at risk for hepatocellular carcinoma using Liver Imaging Reporting and Data System (LI-RADS) categorization^[1]

LI-RADS: Liver Imaging Reporting and Data System; HCC: hepatocellular carcinoma; CT: computed tomography; MRI: magnetic resonance imaging; OPTN: Organ Procurement and Transplantation Network.
* LI-RADS assessment should not be applied to patients <18 years old or those with cirrhosis from congenital hepatic fibrosis or secondary to vascular disorders (eg, Budd-Chiari syndrome, chronic portal vein occlusion, cardiac congestion, hereditary hemorrhagic telangiectasia).
¶ Imaging technology and performance should adhere to standards required for liver lesion characterization, which are more stringent than those for routine abdominal imaging. Contrast-enhanced CT or MRI is preferred over ultrasound (CEUS) to characterize lesions where index of suspicion for HCC or malignancy is high or in patients with multiple lesions requiring LI-RADs categorization. Should the lesion prove to be LR-4, LR-5, or LR-M, CEUS cannot evaluate the entire liver to assess tumor burden for treatment planning nor diagnose HCC using the OPTN criteria for transplant evaluation. In addition, for technical reasons, CEUS cannot categorize multiple lesions simultaneously.
Δ Surveillance imaging for adults at risk for HCC, usually performed with abdominal ultrasound without contrast, is described elsewhere in UpToDate.
◊ Choice of additional imaging should be made in consultation with the radiologist.
§ While the two-year follow-up represents our practice, stability over that time does not confirm that a lesion is benign.
¥ On contrast-enhanced CT or MRI, in order to be categorized as LR-4, lesions that measure <1 cm should be arterially enhancing and demonstrate at least one of these three features: nonperipheral washout, enhancing capsule, or growth. Lesions that are not arterially enhancing can also be categorized as LR-4 if they measure >2 cm and demonstrate one of the three features or measure <2 cm and demonstrate two of the three features. On CEUS, in order to be categorized as LR-4, lesions should be arterially enhancing without washout and measure >1 cm, arterially enhancing with late and mild washout and measure <1 cm, or not arterially enhancing with late and mild washout and measure >2 cm.
‡ If the lesion was diagnosed on CEUS, contrast-enhanced CT or MRI tailored for liver lesion evaluation should be performed to plan therapy.
† For patients who are candidates for liver transplant, most LR-5 lesions meet OPTN criteria for diagnosis of HCC. Refer to UpToDate content for description of pertinent exceptions.
** On contrast-enhanced CT or MRI, in order to be categorized as LR-5, lesions must be arterially enhancing and measure >1 cm. Additionally, those measuring >2 cm should demonstrate at least one of the following three features, and those measuring >1 but <2 cm should demonstrate at least two of the three features: non-peripheral washout, enhancing capsule, or growth. On CEUS, in order to be categorized as LR-5, lesions should measure >1 cm and demonstrate arterial enhancement with late and mild washout. Growth is defined as ≥50% increase in size in ≤6 months with a threshold of ≥5 mm change to avoid error from measurement variability.
¶¶ Examples of HCC without characteristic features are those without arterial enhancement or those with both arterial and delayed enhancement suggesting cholangiocarcinoma.
ΔΔ Approximately 95% of LR-M lesions are malignant. Slightly less than one-half of malignant cases are HCC and the remainder are non-HCC malignancies (eg, cholangiocarcinoma, combined HCC-cholangiocarcinomas, lymphoma, or metastases).
◊◊ Biopsy may alter management for patients being evaluated for liver transplant or for other nonsurgical locoregional therapies (eg, thermal ablation), or if serum tumor markers suggest intrahepatic cholangiocarcinoma or metastasis from an extrahepatic malignancy.