LI-RADS v2018

Liver Imaging Reporting and Data System for CT/MRI

1 Patient Eligibility
LI-RADS applies only to patients at risk for hepatocellular carcinoma (HCC).
2 Check for Special Categories
Tumor in Vein (TIV)
Definite enhancing soft tissue in vein, regardless of parenchymal mass
Targetoid Appearance
Rim APHE, peripheral washout, delayed central enhancement, or targetoid restriction
3 Observation Size

Largest outer-edge to outer-edge dimension of observation

4 Major Features
Arterial Phase Hyperenhancement (APHE)
Non-rim enhancement in arterial phase unequivocally greater than liver
Non-peripheral Washout
Non-rim visually assessed temporal reduction in enhancement relative to liver in PVP or delayed phase
Enhancing "Capsule"
Smooth, uniform, sharp border around most or all of observation in PVP or delayed phase
Threshold Growth
≥50% size increase in ≤6 months, OR new observation ≥10mm

About LI-RADS v2018

The Liver Imaging Reporting and Data System (LI-RADS) is a comprehensive system for standardizing the interpretation and reporting of liver imaging examinations in patients at risk for hepatocellular carcinoma (HCC). Developed by the American College of Radiology (ACR), LI-RADS provides a common lexicon and diagnostic algorithm that reduces variability and improves communication between radiologists and clinicians.

When to Use LI-RADS

LI-RADS applies specifically to patients at risk for HCC, including those with:

  • Cirrhosis of any etiology
  • Chronic hepatitis B infection (even without cirrhosis)
  • Current or prior HCC
  • Liver transplant candidates or recipients for HCC

LI-RADS should NOT be used for patients without these risk factors, in whom different diagnostic considerations apply.

LI-RADS Categories

Category Definition HCC Probability
LR-1 Definitely benign 0%
LR-2 Probably benign Very low
LR-3 Intermediate probability for HCC ~30-40%
LR-4 Probably HCC ~70-80%
LR-5 Definitely HCC >95%
LR-M Probably or definitely malignant, not HCC specific High (non-HCC)
LR-TIV Tumor in vein Definite HCC with vascular invasion

Major Features for HCC Diagnosis

Arterial Phase Hyperenhancement (APHE)

APHE is the hallmark of HCC and reflects the arterial blood supply that characterizes hepatocarcinogenesis. It must be non-rim (whole lesion enhancement) and unequivocally greater than the surrounding liver parenchyma. Rim APHE suggests non-HCC malignancy (LR-M).

Non-peripheral Washout

Washout refers to temporal reduction in enhancement relative to liver, typically seen in the portal venous or delayed phases. It must be non-peripheral (not rim-like) to count as a major feature. Peripheral washout suggests non-HCC malignancy.

Enhancing "Capsule"

A smooth, uniform, sharp border around most or all of the observation, best seen in the portal venous or delayed phases. This feature reflects the fibrous capsule that surrounds many HCCs and distinguishes them from intrahepatic cholangiocarcinoma.

Threshold Growth

Size increase of ≥50% in ≤6 months compared to baseline, OR a new observation ≥10mm. This feature can upgrade observations to LR-5 when combined with APHE and size criteria.

LR-5 Criteria (Definite HCC)

Size Required Features
≥20mm APHE + 1 additional (washout OR capsule)
10-19mm APHE + washout + capsule (all three)
≥10mm with threshold growth APHE only (growth upgrades)

Ancillary Features

Ancillary features can be used to adjust categories (upgrade LR-3 to LR-4, or downgrade LR-4 to LR-3), but cannot be used to upgrade to LR-5.

Favoring Malignancy

  • Mild-moderate T2 hyperintensity
  • Restricted diffusion
  • Corona enhancement
  • Fat sparing in focal steatosis
  • Iron sparing in siderotic liver
  • Transitional phase hypointensity (HBA)
  • Hepatobiliary phase hypointensity (HBA)

Favoring Benignity

  • Size stability ≥2 years
  • Size reduction
  • Parallels blood pool enhancement
  • Undistorted vessels
  • Iron in mass more than liver
  • Marked T2 hyperintensity
  • Hepatobiliary phase isointensity

References

  1. Chernyak V, Fowler KJ, Kamaya A, et al. Liver Imaging Reporting and Data System (LI-RADS) Version 2018: Imaging of Hepatocellular Carcinoma in At-Risk Patients. Radiology. 2018;289(3):816-830. doi:10.1148/radiol.2018181494
  2. American College of Radiology. CT/MRI LI-RADS v2018 Core. Available at: https://www.acr.org/Clinical-Resources/Reporting-and-Data-Systems/LI-RADS
  3. Fowler KJ, Tang A, Santillan C, et al. LI-RADS: A Conceptual and Historical Review from Its Beginning to Its Recent Integration into AASLD Clinical Practice Guidance. J Magn Reson Imaging. 2021;54(5):1412-1422. doi:10.1002/jmri.27394
  4. Mitchell DG, Bruix J, Sherman M, Sirlin CB. LI-RADS (Liver Imaging Reporting and Data System): Summary, Discussion, and Consensus. Hepatology. 2015;61(3):1056-1065. doi:10.1002/hep.27304
  5. Tang A, Bashir MR, Corwin MT, et al. Evidence Supporting LI-RADS Major Features for CT- and MR Imaging-based Diagnosis of Hepatocellular Carcinoma: A Systematic Review. Radiology. 2018;286(1):29-48. doi:10.1148/radiol.2017170554
  6. Marrero JA, Kulik LM, Sirlin CB, et al. Diagnosis, Staging, and Management of Hepatocellular Carcinoma: 2018 Practice Guidance by the American Association for the Study of Liver Diseases. Hepatology. 2018;68(2):723-750. doi:10.1002/hep.29913