*6.1.3.4 Differential imaging diagnostic of adenomas*

*Hepatocellular carcinoma (HCC)* may be hard to distinguish on imaging or pathology. Biliary, vascular, nodal invasion and metastases of HCC typically occur in older, cirrhotic men [42, 45]. Adenoma occurs in young, healthy women.

*Fibrolamellar HCC* is shown as a large, lobulated mass with scar and septa inside. Vascular, biliary invasion and metastases are common.

*Focal nodular hyperplasia (FNH)* is depicted on MRI + C in arterial phase as a homogeneously enhancing mass and in all other phases as an isodense mass comparative to normal liver. In T2WI, a scar is typically seen as hyperintense. On delayed phase MR, FNH uniformly retains Gadoxetate [44, 45]. Gadoxetic acidenhanced MRI can differentiate between HA and FNH with a high sensitivity and specificity [46].

*Hypervascular metastases* are usually multiple. The primary tumor (i.e., thyroid, breast, kidney, or endocrine) must be searched for. CT + C or MRI + C in arterial phase shows heterogeneous enhancement. In portal and delayed phases, hypervascular metastases may appear isodense, hypodense, or hypointense.
