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Magnetite Nanocrystal Clusters with Ultra‐High Sensitivity in Magnetic Resonance Imaging
Author(s) -
Xu Fangjie,
Cheng Changming,
Chen DuXing,
Gu Hongchen
Publication year - 2012
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201100548
Subject(s) - nanocrystal , magnetite , magnetic resonance imaging , materials science , nuclear magnetic resonance , iron oxide , nanotechnology , medicine , radiology , physics , metallurgy
Magnetic iron oxide particles are widely used as contrast agents to improve the sensitivity of magnetic resonance imaging (MRI). Their efficiency in MRI is usually quantified by transverse relaxivity ( r 2 ) in solution. Herein, we synthesized a series of magnetite nanocrystal clusters (MNCs) with ultra‐high transverse relaxivity by a polyol process and studied the relationship between r 2 and size of the MNCs. The sizes of MNCs can be tuned over a wide range from 13 to 179 nm. The r 2 of MNC suspensions as a function of the size of the cluster was analyzed and compared with a theoretical model. We found that MNCs of 64 nm had an r 2 value of 650 m M −1 s −1 , which was more than three times that of the commercial contrast agent and was among the highest reported for iron oxide materials. Compared with the theoretical model, the r 2 value of the MNC suspension is approximately 0.93 of the theoretical prediction. Imaging of the MNC suspensions was performed in a clinical 1.5 T MRI instrument and a comparison was made between MNCs and commercial contrast agents. MRI indicated that the decrease of signal intensity induced by MNCs was in proportion to the r 2 value, which was in accordance with theoretical predictions. These results demonstrate that MNCs with ultra‐high transverse relaxivity and tunable size are promising candidates for molecular imaging and clinical diagnosis in MRI.