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Journal of Nanomaterials
Volume 2012, Article ID 734842, 9 pages
Review Article

Positive Contrast Imaging of SPIO Nanoparticles

Department of Electronic Science and Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen 361005, China

Received 14 December 2011; Revised 19 January 2012; Accepted 27 February 2012

Academic Editor: Carlos Martinez-Boubeta

Copyright © 2012 Chenghong Lin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


It is advantageous to achieve positive contrast images instead of negative contrast images in superparamagnetic iron-oxide (SPIO) nanoparticles-based MR imaging in order to distinguish the signal surrounding SPIO nanoparticles from the dark signal due to local field inhomogeneity and the artifacts due to tissue interface and background noise, eliminate the inherent defects in the traditional MRI such as partial-volume effects and large void volume for reliable visualization, and increase contrast-to-noise ratio. Many methods generating positive signal with SPIO nanoparticles have been developed in the last decade. This paper provides an overview of current visualization methods and states their advantages and disadvantages. In practice, these techniques have been widely applied to cell labeling and disease diagnosis and monitoring. However, there is still a need for an ideal method to achieve both accuracy and sensitivity.