High-field breath-hold MR imaging

The potential of dextran-coated magnetite particles (DM) as a magnetic resonance (MR) imaging contrast agent for liver tumor ws investigated by in vivo MR imaging of rats with hepatocellular carcinoma induced by diethylnitrosamine. T1-weighted (spin echo [SE] 400/20 [repetition time msec/echo time msec]) and T2-weighted (SE 2,000/70) images were obtained before and after intravenous injection of varying doses of dextan-coated magnetite, with use of a 1.5-T superconducting system. A dose of 10 μmol/kg of iron was enough to reduce the signal intensity of liver on both T1- and T2-weighted images, and liver tumors of 2-3 mm were readily detectable. The effect almost disappeared at 24 hours after administration. These results suggest that dextran-coated magnetite is an excellent tissue-specific MR contrast agent for the detection of liver tumors