Metal colloids showing high signal and enhanced contrast in cellular and molecular imaging with MRI and PET/MRI

分子成像使现代医学能够检查生物体中分子和细胞的功能。癌症、动脉粥样硬化和阿尔茨海默病等疾病现在可以在更早的阶段精确地、非侵入性地检测出来。成像扫描仪已经达到了高水平的发展，并且此后正在投入大量的努力来开发具有改进性质的生物标志物。该研究计划解决了分子成像的一个关键方面：在磁共振成像（MRI）和正电子发射断层扫描（PET）中提供高特异性信号的造影剂和示踪剂（生物标志物）的开发。事实上，结合MRI和PET的下一代扫描仪将很快在临床上成为现实。MRI是一种非侵入性成像技术，可在低密度组织中提供高分辨率图像。磁性分子或纳米颗粒通常是精细描绘脉管系统、精确识别疾病伪影和跟踪细胞所必需的。每单位生物标志物的相当差的灵敏度是MRI的主要限制，其需要在体内使用大量的磁性金属。PET也是一种非侵入性成像技术，基于以非常高的灵敏度检测放射性示踪剂。这种方法需要非常少量的放射性原子;然而，分辨率仍然低于MRI。目前，这两种成像技术（MRI和PET）可以分别用于研究生理特征和分子靶点。MRI和PET可以同时进行吗？纳米颗粒形式的磁性金属胶体可用于提高MRI信号的特异性。通过用精心挑选的放射性原子掺杂这些晶体“纳米材料”，下一代生物标志物可以用于双重PET/MRI程序。该研究项目的重点是以磁放射性胶体形式生产的双重造影剂的合成，表征和信号研究。从长远来看，这种胶体可以用作分子标签，细胞标记物，也可以用作生物医学设备的MRI对比度增强剂。

Molecular imaging allows modern medicine to examine the functions of molecules and cells in living organisms. Diseases such as cancer, atherosclerosis and Alzheimer, can now be detected precisely and non-invasively at a much earlier stage. Imaging scanners have reached a high level of development and henceforth intense efforts are being invested in the development of biomarkers with improved properties. This research program addresses a crucial aspect of molecular imaging: the development of contrast agents and tracers (biomarkers) providing high and specific signal in magnetic resonance imaging (MRI) and positron emission tomography (PET). In fact, a next generation of scanners combining MRI and PET will soon become a reality in the clinic. MRI is a non-invasive imaging technique providing high resolution pictures in low density tissues. Magnetic molecules or nanoparticles are often necessary to finely delineate the vasculature, to precisely identify disease artefacts, and to track cells. The rather poor sensibility per unit of biomarker is the major limitation of MRI, which requires the use of large amounts of magnetic metals in-vivo. PET is also a non-invasive imaging technique, based on the detection of radioactive tracers at very high sensitivity. This method requires very small quantities of radioactive atoms; the resolution however remains lower than with MRI. At present, both imaging techniques (MRI and PET) can be used separately for studying physiological features and molecular targets. Could we perform both MRI and PET at the same time? Magnetic metal colloids in the form of nanoparticles, can be used to improve the specificity of the MRI signal. By doping these crystalline "nanomaterials" with carefully selected radioactive atoms, a next generation of biomarkers could become available for dual PET/MRI procedures. This research program focuses on the synthesis, characterization and signal study of dual contrast agents produced in the form of magnetoradioactive colloids. In the long term, such colloids could be used as molecular tags, as cell markers, and also as enhancers of MRI contrast for biomedical devices.