What Do LI-RADS 3, 4, and 5 Mean?

Before the number means anything, the patient has to fit. The CT/MRI LI-RADS v2018 core says to apply it in people at high risk for hepatocellular carcinoma, namely those with:

• cirrhosis, or
• chronic hepatitis B infection, or
• current or prior HCC, including adult liver transplant candidates and recipients.

The same page says not to apply it to people without those risk factors, or to anyone under 18. It is also ruled out when cirrhosis comes from congenital hepatic fibrosis, or from a vascular disorder such as Budd-Chiari syndrome or cardiac congestion.

A spot on a healthy liver is not an LR-anything. If a report uses LI-RADS wording anyway, it is worth asking why.

LI-RADS calls each finding an observation. The v2018 wording for the middle rungs is short:

• LR-3 — intermediate probability of malignancy.
• LR-4 — probably HCC.
• LR-5 — definitely HCC.

The manual describes the mix behind each one. LR-3 observations vary from benign, through dysplastic nodules, to HCC. Most but not all LR-4s are HCC. Almost all LR-5s are HCC.

It also states plainly that the categories reflect probabilities and do not correspond to exact histological categories.

The number is not a general impression. It comes from a table.

The radiologist first checks for nonrim arterial phase hyperenhancement. That means the spot lights up early with contrast, in a set pattern. Then they measure it. There are three size bands: under 10 mm, 10 to 19 mm, and 20 mm or more.

Then they count how many of three extra major features are present:

• an enhancing "capsule" around the edge
• nonperipheral "washout", where the observation fades faster than the liver around it
• threshold growth, defined in v2018 as a size increase of at least 50% within 6 months or less

More features and more millimeters push the number up. An early-enhancing observation of 20 mm or more with no extra feature is LR-4. The same observation at 10 to 19 mm with washout is LR-5.

If the radiologist is unsure whether a feature is there, the rule is to treat it as absent.

LR-5 is the odd one out. In v2018 its criteria were rewritten to match those used by the American Association for the Study of Liver Diseases.

That is why the management table beside it reads "HCC confirmed" rather than "get tissue". In an at-risk liver, imaging that meets these criteria is accepted as the diagnosis.

The reverse is not true. The manual notes three kinds of HCC that cannot be called LR-5: those under 10 mm, those without arterial enhancement, and those with odd features such as rim enhancement. A liver cancer can exist and still not earn the label.

The v2018 core prints management suggestions agreed jointly by the AASLD and LI-RADS:

• LR-3 — repeat or alternative diagnostic imaging in 3 to 6 months.
• LR-4 — multidisciplinary discussion for a tailored workup, which may include biopsy.
• LR-5 — HCC confirmed, then multidisciplinary discussion for agreed management.

Notice that only one of these is a treatment decision. The other two buy information.

LR-3 is the rung that unsettles people most, because it commits to nothing.

Many LR-3s turn out to be vascular pseudolesions, which are quirks of blood flow rather than growths. Others are dysplastic nodules. Some are early cancer.

LI-RADS also allows ancillary features to nudge a category up by one, as far as LR-4. They are not allowed to push anything up to LR-5. That ceiling is deliberate: the strongest label needs the strongest evidence.

• Which category, and how large was the observation?
• Which major features were seen, and which were called absent?
• Was this compared with an older scan?
• Does my liver history match the at-risk group LI-RADS assumes?
• Who is reviewing this, and when does the liver team meet?

A LI-RADS category is about images, not about how you feel today. Do not wait for the next scan if any of the following happens.

• Call 911 or go to an emergency department if you vomit blood, or pass black tarry stools. In a liver at risk, this can mean bleeding from enlarged veins in the food pipe or stomach, which NIDDK lists as a serious complication of cirrhosis.
• Call 911 or go to an emergency department if you become confused, very drowsy, or hard to wake. Confusion, trouble thinking, and personality change are recognised effects of a failing liver.
• Call your care team the same day if the whites of your eyes or your skin turn yellow, or your belly swells quickly and becomes painful. Jaundice and fluid buildup in the belly are both listed among liver cancer symptoms.
• Call your care team within a day or two if you bruise or bleed more easily than usual, or you have a fever with no clear cause.

The system as a whole is covered in What Does LI-RADS Mean. See also Liver Lesion on CT: What Now, Liver Cancer, and Imaging Tests.

• American College of Radiology — LI-RADS
• ACR CT/MRI LI-RADS v2018 Core
• NIDDK (NIH) — Cirrhosis: Symptoms and Causes
• American Cancer Society — Signs and Symptoms of Liver Cancer