Ferromagnetic contrast agents: a new approach.

Most contrast agents used in NMR imaging studies to date have been paramagnetic. However, it is also possible to obtain selective contrast with a ferromagnetic agent, and these agents are potentially more sensitive than paramagnetic compounds because of their large magnetic moments. The water relaxation ability of ferromagnetic, albumin-coated magnetite (Fe3O4) particles has been investigated. These particles are quite effective at reducing both T1 and T2 at relatively low particle concentrations. The potential applications of these particles include improved visualization of the liver, gastrointestinal tract, and genitourinary tract, as well as specific targeting and detection of small tumors or other cells with unique surface receptors.