Focal nodular hyperplasia
Large hepatic focal lesion in segment VIII, showing initial T1 iso-intensity, however, it is clearly identified on DWI. It also demonstrates average post contrast enhancement in the hepatic parenchymal phase together with a central non-enhancing region (central scar). The lesion shows rather benign features and no invasion of the nearby IVC or hepatic veins.
This mass does not show hypervascular enhancement in the arterial phase, since the arterial phase was very early, but FNH is classically an arterially enhancing lesion. Hepatocellular carcinoma is also an arterially-enhancing lesion, and the two entities are differentiated on the delayed phases: FNH fades to background signal intensity and HCC "washes out" relative to the background.
On out-of-phase MRI sequence the mass shows no signal drop denoting no intracellular fat contents, which might have been the case if this was a hepatic adenoma. The presence of a central scar is a typical finding in Focal nodular hyperplasia (FNH), together with the previous exclusions, aid to the diagnosis of FNH with confidence, despite the fact that this is a male patient, as FNH has a high predilection to females.