Superparamagnetic iron oxide imaging of focal liver disease.

The use of iron oxide as a superparamagnetic contrast agent for magnetic resonance imaging of the liver has been described previously. When administered intravenously, superparamagnetic iron oxide (SPIO) is sequestered by the reticuloendothelial system causing significant shortening of the T2-relaxation time. The majority of the contrast is taken up by the reticuloendothelial tissue of the liver. Since tumours have reduced or absent reticuloendothelial tissue the effect on relaxation time is minimal and signal intensity differences between tumour and liver are increased. AMI 25 (Laboratoire Guerbet, Paris) is a colloidal solution of ferrous and ferric oxides. We have performed MR examination of the liver in 16 patients with focal liver lesions using AMI 25 as a superparamagnetic contrast agent. Our results indicate that SPIO significantly increases the conspicuity of focal lesions and the effect is greatest in malignant tumours. We observed no adverse reaction to this contrast agent.