Susceptibility-based MRI contrast of the CSF by intravascular superparamagnetic nanoparticles.

Endorem, a suspension of superparamagnetic iron oxide dextran nanoparticles (NP), have been injected intravenously to healthy anesthetized rats for the purpose of contrast enhancement of brain in gradient-echo imaging at 200 MHz. Not only gray and white matter but also particular regions of the cerebrospinal fluid (CSF) were contrasted in sagittal and transverse images, although samples of this fluid did not contain NP. The selected contrast in the CSF would result form the ability of dense vascular beds containing highly magnetized particles to induce a remote susceptibility effect far beyond the vascular walls into a large fraction of extravascular water.