MRI contrast agent including T1 contrast material coated on surface of nanoparticle support

A magnetic resonance imaging (MRI) method using an iron-based T1 contrast agent for obtaining T1-weighted images in MRI scan, comprising

• (a) introducing the iron-based T1 contrast agent with a T1 relaxivity coefficient (r1) value ranging from approximately 1 mM−1s−1 to 5 mM−1s−1 at 1.5 Tesla on an MRI scanner, into a body fluid of a subject, said iron-based T1 contrast agent producing a bright or positive contrast effect compared to water,
• wherein the MRI iron-based T1 contrast agent consists of
• (i) a non-magnetic nanoparticle support comprising SiO2, a polysaccharide, or a protein wherein a surface of the nanoparticle support comprises surface functional groups, and
• (ii) an iron oxide coating layer having iron oxide bound by coordination bond to the surface functional groups,
• wherein a ratio of thickness of the iron oxide coating layer to a diameter of the non-magnetic nanoparticle support is to 1:25 to 1:6;
• the diameter of the non-magnetic nanoparticle support is 2 to 40 nm;
• and the thickness of the iron oxide coating layer is 0.1 to 1 nm,
• wherein the iron-based T1 contrast agent shortens T1 relaxation time (spin-lattice relaxation time) to induce a positive contrast on T1-weighted images without inducing a negative contrast associated with a T2 contrast agent;
• and
• (b) obtaining T1-weighted images in MRI scan of body parts of the subject.