Quantifying magnetic nanoparticles in non-steady flow by MRI |
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Authors: | Yimin Shen Yu-Chung N. Cheng Gavin Lawes Jaladhar Neelavalli Chandran Sudakar Ronald Tackett Hari P. Ramnath E. Mark Haacke |
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Affiliation: | Department of Radiology, Wayne State University, Detroit, MI, 48201, USA. |
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Abstract: | OBJECTIVE: This work compares the measured [Formula: see text] of magnetic nanoparticles to their corresponding theoretical values in both gel phantoms and dynamic water flows on the basis of the static dephasing theory. MATERIALS AND METHODS: The magnetic moment of a nanoparticle solution was measured by a magnetometer. The [Formula: see text] of the nanoparticle solution doped in a gel phantom was measured at both 1.5 and 4.7 T. A total of 12 non-steady state flow experiments with different nanoparticle concentrations were conducted. The [Formula: see text] at each time point was measured. RESULTS: The theoretical [Formula: see text] on the basis of the magnetization of nanoparticles measured by the magnetometer agree within 11% of MRI measurements in the gel phantom study, a significant improvement from previous work. In dynamic flow experiments, the total [Formula: see text] calculated from each experiment agrees within 15% of the theoretical [Formula: see text] for 10 of the 12 cases. The MRI phase values are also reasonably predicted by the theory. The diffusion effect does not seem to contribute significantly. CONCLUSIONS: Under certain situations with known [Formula: see text] , the static dephasing theory can be used to quantify the susceptibility or concentration of nanoparticles in either a static or dynamic flow environment at a given time point. This approach may be applied to in vivo studies. |
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Keywords: | Nanoparticle concentration Diffusion Magnetic susceptibility IEq8" > /content/918716ujx1h612r4/10334_2008_140_Article_IEq8.gif" alt=" $${{R}_{2}^*}$$" align=" middle" border=" 0" > measurements |
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