Relaxivity Optimization of a PEGylated Iron-Oxide-Based Negative Magnetic Resonance Contrast Agent for T2-Weighted Spin-Echo Imaging
Relaxivity Optimization of a PEGylated Iron-Oxide-Based Negative Magnetic Resonance Contrast Agent for T2-Weighted Spin-Echo Imaging
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DOI：
10.1021/nn204591r
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发表时间：
2012-02-01
期刊：
影响因子：
17.1
通讯作者：
Weller, Horst
中科院分区：
文献类型：
--
作者：
Poeselt, Elmar;Kloust, Hauke;Weller, Horst
根据外球弛豫理论，T-2 MRI造影剂的灵敏度由横向弛豫度r(2)表示，取决于水分子相对于粒径的扩散长度。对于t -2加权自旋回波成像，理论概念揭示了基于纳米晶体尺寸的r(2)弛豫度的三种机制：运动平均机制（MAR）、静态减相机制（SDR）和回波限制机制（ELR）。r(2)最大值对应于SDR，它代表一个小规模的区域。为了验证理论概念并调整SDR，利用peg基配体将超顺磁性氧化铁纳米晶体（SPIOs）可控自组装成直径为30-200 nm的覆树莓状纳米团簇，合成了量身定制的T-2造影剂。该结果强调了通过调整SPIO纳米晶体簇大小来优化T-2造影剂的弛豫度的机会。
Concerning the outer sphere relaxation theory, the sensitivity of a T-2 MRI contrast agent, expressed by the transverse relaxivity r(2), depends on the diffusion length of water molecules relative to the particle size. For T-2-weighted spin-echo imaging, theoretical concepts reveal three regimes regarding the r(2) relaxivity depending on the nanocrystal size: the motional averaging regime (MAR), the static dephasing regime (SDR), and the echo-limiting regime (ELR). The r(2) maximum corresponds to the SDR, which represents a small size regime. To verify the theoretical concepts and to adjust the SDR, tailor-made T-2 contrast agents were synthesized by controlled self-assembly of superparamagnetic iron oxide nanocrystals (SPIOs) into raspberry-like nanoclusters with diameters of 30-200 nm using a PEG-based ligand. The results highlight an opportunity to optimize the relaxivity of T-2 contrast agents by tuning the cluster size of SPIO nanocrystals.