What Does LI-RADS 5 Mean?

LI-RADS stands for Liver Imaging Reporting and Data System. The American College of Radiology built it for people at risk of liver cancer. The goal is that their liver scans get read and reported the same way everywhere.

The categories run from LR-1 to LR-5. LR-5 sits at the top and means definite hepatocellular carcinoma, the main type of primary liver cancer, usually shortened to HCC. Under LI-RADS, an LR-5 observation moves straight to staging and treatment planning with no need for tissue confirmation. In most cancers a biopsy defines the diagnosis. Liver cancer in a scarred liver is the well-known exception.

LI-RADS is not used on every liver scan. It applies to adults 18 and older in one of three groups. The first is people with cirrhosis from a cause other than a blood vessel problem. The second is people with chronic hepatitis B, even without cirrhosis. The third is people with current or past HCC.

Outside those groups the same bright spot means something different. LI-RADS categories are not assigned at all. If you do not have cirrhosis or hepatitis B and an LR number showed up on your report, that is worth clarifying.

LI-RADS builds LR-5 out of a short list of major features, each with a strict definition.

Nonrim arterial phase hyperenhancement (APHE). During the arterial phase of a contrast scan, the spot looks brighter than the liver around it. The brightness fills the spot rather than forming a ring at its edge. HCC grows its own arterial blood supply, which is why it brightens early.

Nonperipheral washout. On the later portal venous or delayed images, the spot turns darker than the liver around it. Again, not just at the rim.

Enhancing capsule. A smooth bright rim appears around the observation on the later images.

Threshold growth. The observation grew by 50% or more in 6 months or less. Any smaller increase does not count.

Size. Size is a feature in its own right, and the cutoffs are 10 mm and 20 mm.

Certain combinations land on LR-5. A spot of 10 to 19 mm with nonrim APHE plus nonperipheral washout is LR-5. Since the 2018 update, that holds no matter how the nodule looked on an earlier screening ultrasound. Nonrim APHE plus threshold growth also reaches LR-5, at 10 to 19 mm and at 20 mm or larger.

Solid, but not absolute, and the published numbers are worth knowing.

A pooled analysis of 49 studies looked at LR-5 observations. HCC was found in 96% on CT, 95% on MRI with extracellular contrast, and 96% on MRI with gadoxetate. The categories performed nearly identically across those three methods. A separate analysis of 7,500 observations put the overall positive predictive value of LR-5 at 95.8%, with a confidence interval of 91.1% to 98.1%.

Not every LR-5 route is equally strong. Take LR-5 reached by nonrim APHE plus threshold growth. In that same analysis its positive predictive value was 74.4% at 10 to 19 mm and 82.4% at 20 mm or larger. Both sit well below the LR-5 average. If your report reached LR-5 through growth rather than washout, it is fair to ask whether the team wants a second look.

The National Cancer Institute states the underlying principle plainly: arterial uptake followed by washout on a single dynamic study is 95% to 100% specific for HCC in lesions 1 to 3 cm.

Three separate assessments usually run at once, and they answer different questions.

Tumor burden comes first: how many lesions, how big, and whether any tumor has grown into a vein. Liver function comes second. NCI describes it as functional hepatic reserve, scored by the Child-Pugh classification, which combines liver blood tests with clinical signs such as ascites. Ascites means fluid in the abdomen. Your general fitness and symptoms come third.

The Barcelona Clinic Liver Cancer system, or BCLC, pulls those three together and is the most widely accepted staging system for HCC. It matters because BCLC does not just label the disease. It points to a treatment.

Options by stage include surgical resection, ablation using heat through a needle, liver transplant, transarterial chemoembolization (TACE), stereotactic body radiation therapy, and drug therapy. For advanced disease the NCI cites median overall survival of 19.2 months with atezolizumab plus bevacizumab and 16.4 months with tremelimumab plus durvalumab. Lenvatinib and sorafenib are alternatives, with regorafenib, cabozantinib, pembrolizumab, and nivolumab plus ipilimumab used later.

This is where the category has direct legal weight in the United States. The Organ Procurement and Transplantation Network accepts an LI-RADS 5 report as a Class 5 lesion for HCC exception scoring, a change that took effect July 1, 2025.

Meeting Class 5 is only part of it. There are two ways to qualify for a standard T2 exception. One is a single Class 5 lesion of at least 2 cm and no more than 5 cm. The other is two or three Class 5 lesions, each at least 1 cm and no more than 3 cm. Alpha-fetoprotein, a blood protein often raised in HCC, must be 1000 ng/mL or below.

Those numbers echo the Milan criteria used in transplant practice: a single lesion under 5 cm, or two to three lesions of 3 cm or less each. Someone whose tumor is larger may still get there through downstaging, meaning locoregional treatment first. In that case the confirming scan must come at least 4 weeks after the last downstaging treatment. There is also a six-month wait from the initial request.

• Which major features produced the LR-5, and was washout among them
• What is the largest lesion in millimeters, and how many lesions are there
• Is there any tumor in a vein, reported as LR-TIV
• What is my Child-Pugh class and BCLC stage
• Do I meet the size and number rules for transplant listing, and what is my AFP
• Has a liver tumor board reviewed this scan yet

• PubMed Central (Radiology) — LI-RADS Version 2018: Imaging of Hepatocellular Carcinoma
• Radiology (RSNA) — Percentages of Hepatocellular Carcinoma in LI-RADS Categories with CT and MRI
• Radiology (RSNA) — Diagnostic Performance of CT/MRI LI-RADS v2018 Major Feature Combinations
• OPTN/HRSA — Alignment of National Liver Review Board Guidance and LI-RADS
• National Cancer Institute — Primary Liver Cancer Treatment (PDQ) Health Professional Version
• American College of Radiology — Liver Imaging Reporting and Data System (LI-RADS)