Spin-lattice relaxation rates in Fe(III)-doped human serum measured by magnetic resonance imaging

The proton spin-lattice relaxation time T1 in iron-doped serum was measured with a magnetic resonance imager operating at 0.5 T. The T1 in aqueous solutions of iron and iron-doped solutions of albumin and gamma globulin was also measured in order to analyse the paramagnetic contribution in iron-doped serum. The enhancement in serum is not linearly dependent on concentration of iron added. It is known that Fe(III) added to serum is mainly complexed with transferrin, albumin, gamma globulin and water. With serum pH (7.9) Fe(III) in the protein solution results in enhancement. Fe(III) in water does not cause any enhancement. As a result, the 1/T1 enhancement in serum should be caused solely by iron-binding serum proteins.