Fig. 2. T 1 and T2 contrast effects. Corresponding T1 relaxation rate of the PB (A) and T2 relaxation rate of the MnFe2O4 (B) as a function of Fe concentration. Linear relationship of r1 (1/T1) (C) and r2 (1/T2) (D) vs. Fe concentration of MPB. (E and F) T1- and T2-weighted MR images of the MPB NPs in aqueous solution at different Fe concentrations.
