Magnetic resonance imaging ancillary features used in Liver Imaging Reporting and Data System: An illustrative review

Table 1 Hepatocellular carcinoma non-specific features suggesting malignancy

Feature	Critical details
Mild to moderate T2 hyperintensity	Well-differentiated HCCs and small moderately differentiated HCCs can be iso or hypointense in T2-WI
	Metastasis and ICC can show mild to moderate T2 hyperintensity
Restricted diffusion	Cirrhotic parenchyma may show restricted diffusion (due to abundance of fibrotic tissue)
	Various HCCs, especially those < 20 mm, tend not to show diffusion restriction
Lesional fat sparing	Applicable in the setting of fatty liver infiltration
	Must be differentiated from hepatic fat sparing areas
Lesional iron sparing	Applicable in the setting of iron-overloaded liver
	May also be observed in other malignancies such as ICC and non-malignant processes such as confluent fibrosis
Diameter increase less than threshold growth	Defined by a diameter increase of a lesion by a minimum of 5 mm, ≥ 50% over ≤ 6 mo or ≥ 100% over > 6 mo
Corona (peri-lesional) enhancement	May also be found in other hypervascular lesions, such as metastasis
	Usually not present in early stage HCCs

HCC: Hepatocellular carcinoma.

Table 2 Hepatocellular carcinoma specific features suggesting malignancy

Feature	Critical details
Intra-lesional fat	Characteristic of early HCC; Exception: Steatohepatitic variant of HCC, which may exhibit marked intralesional fat even if they represent progressed cancer
Nodule-in-nodule architecture	“Subnodule” corresponding to the HCC typically shows enhancement characteristics similar to other HCCs; “Parent” nodule is typically hyperintense on T1-WI, hypointense on T2-WI and hypo- or isoenhancing on the arterial phase (atypical of HCC)
Mosaic architecture	Extremely unusual in other tumors; Uncommon in small HCCs; May be helpful for the diagnosis of large hypovascular HCCs
Blood products	Associated with HCC expansion; Previous biopsy should be discarded

HCC: Hepatocellular carcinoma.