Zinc–Nickel Ferrite Nanoparticles as a Contrast Agent in Magnetic Resonance Imaging N. Sattarahmady 1,2 • M. Heidari 1 • T. Zare 1 • M. Lotfi 3 • H. Heli 1 Received: 30 April 2016 / Revised: 22 May 2016 Ó Springer-Verlag Wien 2016 Abstract Today, contrast agents are used to improve the sensitivity of magnetic resonance imaging (MRI) to detect pathologic structures. Ferrite nanoparticles are a class of superparamagnetic contrast agents in MRI. In this study, Zn 0.5 Ni 0.5 Fe 2 O 4 nanoparticles were synthesized via precipitation method and coated with dextrin to increase the solubility and biocompatibility. The morphology, size, structure, and magnetic properties of nanoparticles were investigated. These nanoparticles have superparamagnetic property with a narrow size distribution with a mean diameter of about 20.5 ± 3.2 nm. MRI study using phantom agar shows that these nanoparticles can be used as an effective contrast agent for T 2 and T à 2 -weighted imaging. The relaxivities of r 2 and r à 2 are 8.78 and 82.08 s -1 mmol L -1 , respectively. From these findings, it is possible that dextrin-coated Zn 0.5 Ni 0.5 Fe 2 O 4 nanoparticles can be used as a good negative contrast agent in MRI. 1 Introduction Magnetic resonance imaging (MRI) is one of the non-invasive and informative techniques with high resolution in diagnostic medicine. However, the difference between the contrast of the images of normal and abnormal tissues is not always sufficient. Using an effective contrast agent, the contrasting of this modality is significantly enhanced [1–3]. & H. Heli hheli7@yahoo.com; heli@sums.ac.ir 1 Nanomedicine and Nanobiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran 2 Department of Medical Physics, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran 3 Department of Radiology, Shiraz University of Medical Sciences, Shiraz, Iran 123 Appl Magn Reson DOI 10.1007/s00723-016-0801-9 Applied Magnetic Resonance