There are several causes for increased hepatic attenuation on CT. In this case, the differentiating feature of primary hemochromatosis is the increased density of the liver only. In secondary hemochromatosis (e.g. frequent transfusions), the spleen would be expected to be hyperdense as well.

CT is not suitable for quantifying iron load in the liver, although this was practised in some institutions until the 1990s ¹. However, MR quantification of iron content in the liver, using several gradient recalled echo sequences, is a non-invasive alternative to biopsy. 

Cavernous hemangiomas of the liver are classically hypointense relative to liver parenchyma on T1-weighted imaging. In this case, the hemangiomas appear relatively hyperintense because of the diffuse signal drop in the liver parenchyma secondary to iron deposition; there is little, if any iron deposition in the hemangioma.

A hyperdense liver on non-contrast CT is an 'old chestnut' radiology exam case. Watch out for ancillary features that may point to the diagnosis such as pulmonary fibrosis and pacemaker (amiodarone), or increased density in the spleen and pancreas (secondary hemochromatosis).