A synergistically enhanced T(1) -T(2) dual-modal contrast agent.
A synergistically enhanced T(1) -T(2) dual-modal contrast agent.
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DOI：
10.1002/adma.201203169
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发表时间：
2012-12-04
影响因子：
29.4
通讯作者：
Gao, Jinhao
中科院分区：
文献类型：
--
作者：
Zhou, Zijian;Huang, Dengtong;Bao, Jianfeng;Chen, Qiaoli;Liu, Gang;Chen, Zhong;Chen, Xiaoyuan;Gao, Jinhao
NIH-PA作者Mannipt组织分子。[1]MRI造影剂，通常以T1阳性造影剂和T2阴性造影剂的形式，可以通过增加目标与背景的对比度来大大提高MRI的灵敏度。例如，具有强磁矩的超顺磁性氧化铁（SPIO）纳米颗粒是主要的T2造影剂，特别是在来自正常组织的病变的成像和检测中。[2]然而，SPIO纳米颗粒作为T2造影剂的显著缺点是磁化率伪影和负对比效应（即暗MR图像），[3]这可能限制其临床应用。相反，T1成像，通常使用顺磁性材料作为造影剂，由于其高信号强度（明亮和阳性MR图像），在组织之间具有优异的分辨率。[4]虽然超小（直径约3 nm）的氧化铁纳米颗粒可以用作T1造影剂，[5]但具有7个未配对电子的钆物质仍然是临床使用的主要T1造影剂。[4]多种成像模式的组合可以产生互补的诊断信息，并提供优于单一模式的协同优势。[6]MRI的T1-T2双模态策略引起了相当大的兴趣，因为它可以通过在具有高组织分辨率的T1成像和具有高检测病变可行性的T2成像中的有益对比效应来提供高度准确的诊断信息。[7]此外，考虑到各种成像技术的不同穿透深度和空间/时间分辨率，在一个仪器设备内的多模态成像更适用和上级。T1-T2双模态MRI技术的迫切需求是开发新的、性能优良的双模态造影剂（DMCA）。氧化铁（磁铁矿和磁赤铁矿）纳米粒子和Gd物种的“核-壳”格式的集成已被开发为DMCA最近。[8]然而，由于T1造影剂的强磁耦合和高磁化率效应，由超顺磁性纳米颗粒产生的磁场干扰了氧化铁纳米颗粒外部的顺磁性物质的弛豫过程（图1a），这引起了T1信号的不期望的降低。[8c]一般来说，超顺磁性T2造影材料很容易通过外部磁场产生感应磁场，并可能影响顺磁性T1造影材料的电子自旋，具体取决于它们的位置（图1）。内部T1对比材料表现出与T2对比材料诱导的磁场方向相同的平行自旋有序。因此，T2造影剂增加了T1造影剂的局部磁场强度（图1b），导致对T1弛豫速率的影响更大，最终增强了T1造影效果。基于这一基本原理，我们在此报告了一种新的和方便的策略来设计协同增强的T1-T2 DMCA。
NIH-PA Author Manuscript molecules of tissues.[1] MRI contrast agents, generally in the form of T1 positive contrast agents and T2 negative contrast agents, can greatly improve the sensitivity of MRI by increasing the contrast of the target from the background. For example, superparamagnetic iron oxide (SPIO) nanoparticles with strong magnetic moments are the prevailing T2 contrast agents, especially in the imaging and detection of lesions from normal tissues.[2] The significant drawbacks of SPIO nanoparticles as T2 contrast agents are, however, magnetic susceptibility artifacts and negative contrast effects (ie, dark MR images),[3] which may limit their clinical applications. On the contrary, T1 imaging, typically using paramagnetic materials as contrast agents, has excellent resolution between tissues due to its high signal intensity (bright and positive MR images).[4] Although ultrasmall (~ 3 nm in diameter) iron oxide nanoparticles can be used as T1 contrast agents,[5] the gadolinium species possessing seven unpaired electrons are still the prevailing T1 contrast agents in clinical use.[4]The combination of multiple imaging modalities can yield complementary diagnostic information and offer synergistic advantages over the single modality.[6] The T1–T2 dualmodal strategy for MRI has attracted considerable interest because it can give highly accurate diagnostic information by the beneficial contrast effects in both T1 imaging with high tissue resolution and T2 imaging with high feasibility on detection of a lesion.[7] Moreover, considering the different penetration depths and spatial/time resolutions of various imaging techniques, the multimodal imaging within one instrumental device is more applicable and superior. The urgent demand of T1–T2 dual-modal MRI techniques is the development of new and excellent dual-modal contrast agents (DMCAs). The integration of iron oxide (magnetite and maghemite) nanoparticles and Gd species in a “core–shell” format has been developed as DMCAs recently.[8] However, the magnetic field generated by a superparamagnetic nanoparticle perturbs the relaxation process of the paramagnetic species outside the iron oxide nanoparticle (Figure 1a) because of the strong magnetic coupling and high susceptibility effect of T1 contrast materials, which induces an undesirable decrease of the T1 signal.[8c] In general, the superparamagnetic T2 contrast material easily generates an induced magnetic field by an external magnetic field and may affect the electronic spins of paramagnetic T1 contrast materials depending on their locations (Figure 1). The inside T1 contrast material exhibits parallel spin ordering with the same direction of magnetic field induced by the T2 contrast material. Therefore, T2 contrast material increases the local magnetic field intensity of the T1 contrast material (Figure 1b), resulting in greater impact on T1 relaxation rates, and finally enhances the T1 contrast effect. Based on this rationale, we report herein a new and convenient strategy to design a synergistically enhanced T1–T2 DMCA.
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影响因子：
4.7
作者：
Bae, Ki Hyun;Kim, Young Beom;Park, Tae Gwan
通讯作者：
Park, Tae Gwan
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