Liver Imaging Reporting and Data System for CT/MRI
1 Patient Eligibility
LI-RADS applies only to patients at risk for hepatocellular carcinoma (HCC).
If patient is NOT at risk for HCC, LI-RADS does not apply. Consider alternative diagnostic algorithms.
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
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
American College of Radiology. CT/MRI LI-RADS v2018 Core. Available at: https://www.acr.org/Clinical-Resources/Reporting-and-Data-Systems/LI-RADS
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
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
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
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