Characterization of magnetic nanoparticles as contrast agents in magnetic resonance imaging using high-Tc superconducting quantum interference devices in microtesla magnetic fields

In this paper, we characterize the spin-lattice relaxation T-1, spin-spin relaxation T-2, and effective relaxation rate Gamma(MF) of magnetic fluids for magnetic resonance imaging using a high-T-c superconducting quantum interference device ( SQUID) in microtesla magnetic fields. When the magnetic susceptibility of the magnetic fluid was increased, a broadening of proton nuclear magnetic resonance spectra and a growing spin-lattice relaxation T-1 as well as spin-spin relaxation T-2 were observed. The effective relaxation rate Gamma(MF) increased monotonically from 0 to 13 s(-1) when the magnetic susceptibility of the magnetic fluids, relative to tap water, was increased from 0 to 0.0015 emu g(-1). We demonstrate the magnetic fluid as an image contrast via a high-T-c SQUID in microtesla magnetic fields.