Well-differentiated hepatocellular carcinoma: isointense to liver parenchyma on superparamagnetic iron oxide-enhanced MR.

We present a patient with hepatocellular carcinoma that was identified on precontrast MR and became isointense to liver parenchyma after the intravenous administration of superparamagnetic iron oxide. The tumor was well-differentiated hepatocellular carcinoma and contained approximately the same number of Kupffer cells as liver parenchyma on pathological examination. Our case suggests that superparamagnetic iron oxide may give confusing results if the hepatic mass, e.g., hepatocellular carcinoma, contains Kupffer cells.