Relaxometry Measurements of Europium-doped Mn0.6Zn0.4Fe2O4 at Increasing Magnetic Field

Magnetic resonance imaging (MRI) contrast agents with both intrinsic high r1 and r2 relaxivities are desirable in medical diagnosis to achieve highly accurate and ambiguity-free MR images. Here, we report synthesis and MRI tests of Europium doped Mn-Zn ferrite (EuMZF) nanoparticles at different magnetic field strengths. EuMZF nanoparticles showed significant improvement in both positive (T1) and negative (T2) contrasts. The results showed that by increasing magnetic field, r1 relaxivity decreased while r2 increased so that the EuMZF is suitable as a dual-mode contrast at 1.5 and 3T but it is a T2 agent at 7 and 9.4T.