Definitions:

• Cirrhosis-associated nodules represent a histological spectrum that includes cirrhotic nodules (CNs) (which include regenerative nodules (RNs)), low-grade dysplastic nodules (LGDNs), high-grade dysplastic nodules (HGDNs), and HCC.  

LI-RADS Categorization:

• Cirrhosis-associated nodules with the imaging features below may be considered probably benign (all of the following) and categorized as LR-2:
• Diameter < 20mm AND
• Homogeneous AND
• Isoenhancement to background cirrhotic nodules in all phases AND
• Differ from background nodules by having one or more of the following features:
• Distinctly larger than background nodules (but still < 20mm)
• Mild to moderate CT hyperattenuation
• Mild to moderate T1 hyperintensity
• Mild T2 or T2* hypointensity
• Moderate or marked T2 or T2* hypointensity (e.g., iron-rich cirrhosis associated nodules)
• Cirrhosis-associated nodules that are distinct in imaging appearance from background nodules but that do not meet LR-2 criteria cannot be considered probably benign. These include nodules with any of the following features:
• Diameter ≥ 20mm OR
• Heterogeneous in one or more sequences or phases OR
• Enhancement that differs from liver in one or more phases OR
• Any ancillary feature that favors malignancy
• Cirrhosis-associated nodules that do not meet LR-2 criteria should be categorized as LR-3, LR-4, or LR-5 based on size and the presence of major and ancillary features

LI-RADS Reporting:

• LR-2 cirrhosis-associated nodules are common in cirrhosis and generally do not require LI-RADS reporting.  Radiologists at their discretion may report them.
• LR-3 cirrhosis-associated nodules should be reported based on the presence of LR-4, LR-5, or LR-M observations elsewhere in the liver.
• LR-4 and LR-5 observations must be reported 

Comments:

• The cirrhotic liver contains innumerable cirrhosis-associated nodules. Except in cases of highly advanced HCC in which most of the hepatic parenchyma is replaced by tumor, the vast majority of such nodules are CNs.
• In patients with cirrhosis, CNs are diffusely distributed throughout the liver, but depending on imaging technique and other factors may not be discernible as discrete lesions.
• When visible at CT or MRI as discrete lesions, CNs tend to be uniform in size and other imaging features. Hence, while CT and MRI usually cannot provide a specific histological diagnosis, cirrhosis-associated nodules that are uniform in size and other imaging features are highly likely to be CNs. Such nodules are expected findings in cirrhosis and require no LI-RADS categorization.
• Nodules distinctly different from background nodules in one or more imaging features (e.g., size, attenuation/signal intensity, enhancement pattern, morphology/architecture, fat content, iron content) usually require LI-RADS categorization, as there is greater likelihood that the nodules represent LGDNs, HGDNs, or HCCs. Such nodules should be categorized LR-2 or greater.