Presentation
This patient with known hemochromatosis underwent an ultrasound of liver because of weight loss and malaise. AFP within normal limits.
Patient Data
On B-mode ultrasound, the liver parenchyma is of increased echogenicity and coarse echotexture. Centered in segment VIII, there is a well-defined 4.5 cm mass of heterogeneous echotexture.
The patient was referred for urgent 4-phase liver because of suspected hepatocellular carcinoma.
On non-contrast CT, the liver is of diffusely increased density. The hepatic vasculature and biliary tree appear conspicuous due to their relative hypodensity. The density of the spleen and pancreas appear normal. The lesion seen on ultrasound appears as a mass hypodense relative to liver parenchyma.
The mass in segment VIII demonstrates peripheral nodular enhancement on arterial phase. Portal and hepatic veins remain conspicuous against hyperdense liver parenchyma. There is a progressive centripetal enhancement of the mass until complete fill-in on 5-minute delayed phase, where the liver is now of homogeneous attenuation.
Signal changes in the liver are in keeping with iron deposition in hemochromatosis. A second cavernous hemangioma is shown in segment IV.
T2 BLADE fat-suppressed with an echo train of 116ms. The segment VIII mass is hyperintense, "lightbulb bright"'. There is a diffuse signal drop throughout the liver (susceptibility).
Low signal liver parenchyma on T1 in-phase. The mass is hyperintense relative to the liver.
Paradoxical increase in signal of the liver parenchyma on T1 out-of-phase, yet the mass is hyperintense relative to liver parenchyma.
40-minute post IV gadoxetate sodium (hepatocyte-specific contrast agent).
Case Discussion
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).
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