LIRADS is a standardized system for interpreting and reporting findings of liver imaging to improve detection of hepatocellular carcinoma (HCC). It provides strict criteria and algorithms to categorize liver lesions identified on ultrasound, CT or MRI as definitely or probably benign (LR-1 to LR-3) or HCC (LR-4 to LR-5). The system aims to improve consistency and communication between radiologists and clinicians to help determine appropriate management. Major updates since 2011 have refined the diagnostic criteria and introduced algorithms for assessing treatment response to locoregional therapies for HCC. LIRADS is now integrated into American guidelines for diagnosis and treatment of HCC.

1. LIRADS
(Liver Imaging Reporting And Data System)
Dr Pukar Thapa
DM Resident (HEPATOLOGY)
May 26th, 2020

2. Introduction
• Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and the third leading cause of cancer-
related mortality worldwide.
• Early detection of HCC is important as it has been shown to improve overall survival, particularly when patients are
able to receive potentially curative therapy such as resection or orthotopic liver transplantation.
• The diagnosis of HCC may be made noninvasively by imaging findings alone, often without the need for
percutaneous biopsy, in patients who are considered to be at high risk for HCC.
• Consequently, radiologists must be accurate in their interpretation and reporting of liver imaging so that therapy may be
rendered to patients with HCC in an appropriate and timely manner.
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.

3. LIRADS
• LI-RADS provides a standardized lexicon, strict diagnostic criteria, an easy-to-follow diagnostic algorithm, and
reporting guidelines to improve the consistency and clarity of radiologist interpretation and reporting.
• One benefit of LI-RADS is improved communication between radiologists and clinicians.
• According to the LI-RADS diagnostic algorithm, each liver observation in a patient at high risk for HCC is assigned a
category (from LR-1 to LR-5) reflecting the relative likelihood of being HCC.
• LI-RADS is supported and endorsed by the American College of Radiology (ACR) and in 2018 was integrated into the
American Association for the Study of Liver Diseases (AASLD) guidance statement for HCC.

4. Overview of major Li-RADS updates
• Li-RADS v2011
• The initial version of LI-RADS was released in 2011 with a standardized lexicon and five major categories for
classifying observations in the liver:
• LR-1 (definitely benign),
• LR-2 (probably benign),
• LR-3 (intermediate probability for HCC),
• LR-4 (probably HCC), and
• LR-5 (definitely HCC).

5. 2013Li-RADS 2014Li-RADS 2017Li-RADS 2018Li-RADS
Overview of major Li-RADS updates
Introduced a diagnostic table
and imaging atlas.
• Introduced material on hepatobiliary agents.
• Split cell was introduced into the algorithm.
• The lexicon and atlas were refined and
expanded.
• Added new algorithms for US surveillance and
CT/MRI treatment response assessment.
• The category LR-noncategorizable (LR-NC) was
added.
Unified LI-RADS and AASLD

6. US Li-RADS
• Ultrasound is the most commonly used method for surveillance in patients at risk for HCC.
• It has the benefit of being a noninvasive, accessible, safe, and low-cost screening tool for HCC.
• In a meta-analysis of 15 scientific studies on HCC surveillance in patients with cirrhosis, sonography had a pooled
sensitivity of 47% for early-stage cancer detection.
• Two prospective, randomized controlled trials in East Asia have shown that ultrasound surveillance decreased
HCC-related mortality by 31%–37%.
An ACR-endorsed working group developed a new LI-RADS algorithm specific to the interpretation of HCC
screening and surveillance by ultrasound (US LI-RADS).
1. Tzartzeva K, Obi J, Rich NE, et al. Surveillance imaging and alpha deto-protein for early detection of hepatocellular carcinoma in patients with cirrhosis: a meta-analysis.
Gastroenterology.2018;154(6):1706–1718.e1.
2. Zhang BH, Yang BH, Tang ZY. Randomized controlled trial of screening for hepatocellular carcinoma. J Cancer Res Clin Oncol. 2004;130(7):417–422.
3. Yeh YP, Hu TH, Cho PY, et al; Changhua Community-Based Abdominal Ultrasonography Screening Group. Evaluation of abdominal ultra-sonography mass screening for hepatocellular
carcinoma in Taiwan. Hepatology. 2014;59(5):1840–1849.

7. Patients at the highest risk for HCC
AASLD 2018

8. The inclusion and exclusion criteria of Li-RADS (CT, MRI and
ultrasound surveillance)
• The AASLD recommends not
performing surveillance of
patients with cirrhosis with
Child’s class C unless they are on
the transplant waiting list, given
the low anticipated survival for
patients with Child's C cirrhosis.
ACR and AASLD 2018

9. • The US LI-RADS algorithm includes two components:
• Ultrasound category
• Visualization score
US Li-RADS

10. Ultrasound category
• American College of Radiology. Ultrasound Li-RADS v2017. https://www.acr.org/Clinical-Resources/Reporting-and-Data-Systems/Li-
RADS/Ultrasound-Li-RADS-v2017.
OR AFP ≥ 20 ng/ml

11. Visualization score
• The visualization score is assigned to each examination based on technical quality and study limitations and
conveys the expected sensitivity of the examination for detection of liver lesions.
• Multiple extrinsic and intrinsic factors can affect the quality of ultrasound visualization of the liver parenchyma
including the:
• patient body habitus,
• obscuration of the liver by lung or bowel gas,
• a patient’s inability to hold their breath or hold still,
• hepatic parenchymal heterogeneity or sound attenuation due to fibrosis/cirrhosis or steatosis.

12. • American College of Radiology. Ultrasound Li-RADS v2017. https://www.acr.org/Clinical-Resources/Reporting-and-Data-Systems/Li-
RADS/Ultrasound-Li-RADS-v2017.
It is important to note that currently the visualization score does not impact management recommendations

13. US LI-RADS Definitions and Category Criteria

14. US LI-RADS Definitions and Category Criteria

15. US LI-RADS Definitions and Category Criteria

16. US LI-RADS Definitions and Category Criteria
OR AFP ≥ 20 ng/ml

17. US-LIRADS algorithm – STEP 1 (Assign US-LIRADS category)

18. US-LIRADS algorithm – STEP 2 (Apply Tiebreaking rule if needed)
Tiebreaking rules: Rules to assign a final single category when
deciding between two categories.
For screening or surveillance exam (US LI-RADS):
Assign the category with a higher degree of suspicion.
Rationale: In screening context, goal is to maximize sensitivity
For diagnostic exam (CT/MRI LI-RADS):
Assign the category with a lower degree of certainty.
Rationale: In diagnostic (confirmatory) context,
emphasis is on specificity.

19. US-LIRADS algorithm – STEP 3 (Assign US LI-RADS Visualization
Score)

20. US-LIRADS algorithm – STEP 4 (Final check)
After Steps 1, 2, and 3 – See if the assigned US category and visualization score seem
reasonable and appropriate
If YES: Its done.
If NO: Assigned US category and/or visualization score may be inappropriate, so
reevaluate.

21. Recommendation for US category
Category 1 Continue routine surveillance every 6 months.
Category 2 Close follow-up with short-interval ultrasound every 3–6 months to identify
growth beyond the 1 cm threshold, in which case, further characterization with a
contrast-based study is warranted.
If an observation in an US-2 study is stable in size for 2 years or greater, the
patient can return to routine 6-month surveillance.
Category 3 Further characterization with multiphase contrast-enhanced CT, MRI, or CEUS
AASLD 2018

22. US Li-RADS Category 3 observation in a 59-year-old male
with hepatitis C cirrhosis undergoing US surveillance.
Notes: Sagittal US image shows a 3.6 cm solid hypoechoic
observation with lobulated margins in segment 6. This
patient requires contrast-based studies; CeUS,
CeCT, or CeMRi to further characterize the lesion.
US Li-RADS Category 3 observation in a 70-year-old female
with cryptogenic cirrhosis undergoing US surveillance.
Notes: Transverse US image shows a large area of
heterogeneity (arrows) distinctive from background liver,
shown to represent an HCC with infiltrative
Appearance.

23. CT/MRI LIRADS

24. Application of CT/MRI LIRADS (diagnostic population)
AASLD 2018

25. CT/MRI LI-RADS Categories

26. CT/MRI LI-RADS Categories
Of all LR-2 lesions about 16% are
HCC and 18% are malignant.
Of all LR-3 lesions approximately
37% are HCC and 39% are
malignant
Of all LR-4 observations about
74% are HCC and 81% are
malignant
Of all LR-5 lesions 95% are HCC
and 98% are malignant.

27. CT/MRI LI-RADS Categories (Diagnostic table)

28. LI-RADS Major Imaging Features
Nonrim-like enhancement in arterial phase unequivocally greater
in whole or in part than liver.
Enhancing part must be higher in attenuation or intensity than
liver in arterial phase.
Nonperipheral visually assessed temporal reduction in enhancement in whole
or in part relative to composite liver tissue from earlier to later phase resulting
in hypoenhancement in the extracellular phase:
• portal venous or delayed phase if ECA or gadobenate is given
• portal venous phase if gadoxetate is given

29. • There is an observation with non-rim hyperenhancement (yellow arrow).
In a late phase there is washout. These are typical features of HCC.
LI-RADS Major Imaging Features
The other lesion (green
arrow) is a treated lesion.

30. • Seventy-one-year-old female
demonstrating nonrim arterial phase
hyperenhancement.
• Notes: Contrast-enhanced CT shows a
large mass (arrows) in the left hepatic
lobe, partially exophytic, demonstrating
heterogeneous arterial phase
hyperenhancement.
• Posthepatectomy pathology confirmed
well-differentiated hepatocellular
carcinoma.
LI-RADS Major Imaging Features

31. LI-RADS Major Imaging Features
Smooth, uniform, sharp border around most or all of an observation,
unequivocally thicker or more conspicuous than fibrotic tissue around
background nodules, and visible as as enhancing rim in PVP, DP, or
TP.
Largest outer-edge-to-outer-edge dimension of an observation:
• Include “capsule” in measurement.
• Pick phase, sequence, plane in which margins are clearest.
• Do not measure in arterial phase or DWI if margins are clearly visible on
different phase (size may be overestimated in arterial phase)

32. • Patient with an enhancing lesion and washout. Note the enhancing capsule on the delayed phase.
• A capsule is one of the major features of HCC and can be complete or partial.
A capsule should always be included within the measurement of the lesion.
LI-RADS Major Imaging Features

33. LI-RADS Major Imaging Features
Size increase of a mass by ≥ 50% in ≤ 6 months
• Apply threshold growth only if the observation unequivocally is a mass.
Do not apply threshold growth if there is a reasonable possibility that the
observation is a pseudolesion such as a perfusion alteration.
• Apply threshold growth only if there is a prior CT or MRI exam of
sufficient quality and appropriate technique to gauge if growth has
occurred. Do not assess threshold growth by comparing to prior US or
CEUS exams.
• Measure on same phase, sequence, and plane on serial exams if possible.

34. • The images show an observation in segment 5 of the liver demonstrating arterial hyperenhancement.
The lesion has grown from 8 mm to 21 mm in 3 months, which means that there is threshold growth.
LI-RADS Major Imaging Features

35. LI-RADS Major Imaging Features (Tumor in Vein LR-TIV)
Unequivocal enhancing soft tissue in vein,
regardless of visualization of parenchymal mass
Additional clues to diagnosis of tumor in vein:
Imaging features that suggest tumor in vein but do NOT establish its presence are listed below:
• Occluded vein with ill-defined walls
• Occluded vein with restricted diffusion
• Occluded or obscured vein in contiguity with malignant parenchymal mass
• Heterogeneous vein enhancement not attributable to artifact.

36. a) Arterial phase MDCT shows a large hypovascular mass, which invades the portal vein bifurcation (arrow). There
are multiple solid nodules present in both lobes, most likely metastases.
b) Venous phase MDCT confirms hypovascularity of the tumour.
c) Paraxial volume-rendered technique demonstrates the extent of tumour thrombosis in the left system (arrows).
LI-RADS Major Imaging Features (Tumor in Vein LR-TIV)

37. • Targetoid mass
• Target-like imaging morphology. Concentric arrangement of internal components.
• Likely reflects peripheral hypercellularity and central stromal fibrosis or ischemia.
• OR
• Nontargetoid mass with one or more of the following:
• Infiltrative appearance.
• Marked diffusion restriction. No tumor in vein
• Necrosis or severe ischemia. Not meeting LR-5 criteria
• Other feature that in radiologist’s judgment suggests non-HCC malignancy.
LI-RADS Major Imaging Features (LR-M criteria)

38. • A 2 cm observation in hepatic segment 5 shows
• (A) rim arterial phase hyperenhancement,
• (B) progressive delayed central enhancement on portal venous, and
• (C) delayed phase, corresponding to a targetoid appearance (LR-M). Biopsy confirmed intrahepatic cholangiocarcinoma.
LI-RADS Major Imaging Features (LR-M criteria)

39. CT/MRI-LIRADS algorithm – STEP 1 (Apply CT/MRI LI-RADS
Diagnostic Algorithm )

40. CT/MRI-LIRADS algorithm – STEP 1 (Apply CT/MRI LI-RADS
Diagnostic Algorithm )
If unsure about the presence of any major feature: characterize that feature as absent.

41. CT/MRI-LIRADS algorithm – STEP 2 (Optional: Apply Ancillary
Features (AFs) )
Ancillary features may be used at radiologist discretion for: Improved
detection, increased confidence, or category adjustment.
For category adjustment (upgrade or downgrade), apply ancillary features as follows:
≥ 1 AF favoring malignancy: upgrade by 1 category up to LR-4 (Absence of these AFs should not be used to
downgrade)
≥ 1 AF favoring benignity: downgrade by 1 category (Absence of these AFs should not be used to upgrade)
If ≥ 1 AF favoring malignancy and ≥ 1 AF favoring benignity: Do not adjust category
Ancillary features cannot be be used to upgrade to LR-5

42. Ancillary features
If unsure about presence of any ancillary feature: characterize that feature as absent

43. CT/MRI-LIRADS algorithm – STEP 3 (Apply Tiebreaking Rules if
Needed)
If unsure between two categories, choose the one reflecting lower certainty
If unsure about presence of TIV,
do not categorize as LR-TIV

44. CT/MRI-LIRADS algorithm – STEP 4 (Final check)
After Steps 1, 2, and 3 – Re-assess if the assigned category seems
reasonable and appropriate
If YES: Its done, move on the next observation (if any).
If NO: Assigned LI-RADS category may be inappropriate, so reevaluate.

45. CT/MRI LI-RADS-Based Management: Suggested Imaging
Workup Options & Time Intervals
Untreated observations
AASLD 2018

46. LI-RADS treatment response
The LI-RADS treatment response algorithm was introduced in v2017 to guide interpretation of response following
locoregional therapy (but do not apply to systemic treatment response; the system can be used with caution in
patients undergoing both locoregional and systemic therapy when the locoregional treatment effects are
dominant).

47. CT/MRI Treatment Response Table

48. CT/MRI-LIRADS treatment response algorithm – STEP 1 (Apply
algorithm)

49. CT/MRI-LIRADS treatment response algorithm – STEP 2
(Measure Viable tumor Size)

50. If unsure between two categories, choose the one reflecting lower certainty
CT/MRI-LIRADS treatment response algorithm – STEP 3 (Apply
Tiebreaking Rules if Needed)

51. CT/MRI-LIRADS treatment response algorithm – STEP 4 (Final
check)
After Steps 1, 2, and 3 – Re-assess if the assigned category seems
reasonable and appropriate
If YES: Its done, move on the next observation (if any).
If NO: Assigned LI-RADS category may be inappropriate, so reevaluate.

52. Response category (figures)

53. CT/MRI LI-RADS-Based Management: Suggested Imaging
Workup Options & Time Intervals
Treated Observations
AASLD 2018