Computed tomography-guided time-domain diffuse fluorescence tomography in small animals for localization of cancer biomarkers.
Computed tomography-guided time-domain diffuse fluorescence tomography in small animals for localization of cancer biomarkers.
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DOI：
10.3791/4050
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发表时间：
2012-07-17
期刊：
影响因子：
--
通讯作者：
Pogue BW
中科院分区：
文献类型：
--
作者：
Tichauer KM;Holt RW;Samkoe KS;El-Ghussein F;Gunn JR;Jermyn M;Dehghani H;Leblond F;Pogue BW
小动物荧光分子成像（FMI）可以成为临床前药物发现和开发研究的有力工具1。然而，组织发色团（例如，血红蛋白、水、脂质、黑色素）通常限制光信号通过大于几毫米2的厚度的传播。与其他可见波长相比，组织对红色和近红外（near-IR）光的吸收显著降低，并且非弹性散射成为主要的光-组织相互作用机制。吸收和发射近红外范围（600-1000 nm）内的光的荧光剂的相对较新的发展推动了成像系统和光传播模型的发展，这些模型可以在小动物中实现全身三维成像3。尽管在这一领域取得了很大的进步，但扩散荧光断层扫描的不适定性仍然是图像重建技术的稳定性、对比度恢复和空间分辨率的一个重要问题，并且在小动物中进行FMI的最佳方法尚未达成一致。大多数研究小组已经投资于基于电荷耦合器件（CCD）的系统，该系统提供丰富的组织采样，但灵敏度不理想4 -9，虽然我们的小组和其他一些人10 -13已经追求基于非常高灵敏度的检测器的系统，但是此时仅以低成像吞吐量为代价来实现致密组织采样。在这里，我们展示了在荧光断层扫描系统中应用单光子检测技术来定位小鼠模型中的癌性脑病变的方法。荧光断层扫描（FT）系统采用单光子计数，使用光电倍增管（PMT）和信息丰富的时域光检测在非接触构象11。这提供了传输的激发和发射光的同时收集，并且包括自动荧光激发曝光控制14、激光参考以及与小动物计算机断层扫描（microCT）系统的共配准15。裸鼠模型用于成像。动物在左大脑半球原位接种人神经胶质瘤细胞系（U251），2周后成像。通过注射靶向表皮生长因子受体的荧光示踪剂IRDye 800 CW-EGF（LI-COR Biosciences，林肯，NE）使肿瘤发荧光，表皮生长因子受体是已知在U251肿瘤系和许多其他癌症中过表达的细胞膜蛋白18。还注射了第二种非靶向荧光示踪剂Alexa Fluor 647（Life Technologies，Grand Island，NY），以解释对靶向示踪剂摄取的非受体介导的作用，从而提供定量示踪剂结合和受体可用性/密度的方法27。使用CT引导的时域算法来重建两种荧光示踪剂的位置（即，肿瘤的位置）和它们定位肿瘤的能力通过对比增强的磁共振成像来验证。虽然在神经胶质瘤小鼠模型中证明了荧光成像，但本视频中提出的方法可以扩展到各种小动物模型中的不同肿瘤模型，可能高达大鼠的大小17。
Small animal fluorescence molecular imaging (FMI) can be a powerful tool for preclinical drug discovery and development studies1. However, light absorption by tissue chromophores (e.g., hemoglobin, water, lipids, melanin) typically limits optical signal propagation through thicknesses larger than a few millimeters2. Compared to other visible wavelengths, tissue absorption for red and near-infrared (near-IR) light absorption dramatically decreases and non-elastic scattering becomes the dominant light-tissue interaction mechanism. The relatively recent development of fluorescent agents that absorb and emit light in the near-IR range (600-1000 nm), has driven the development of imaging systems and light propagation models that can achieve whole body three-dimensional imaging in small animals3. Despite great strides in this area, the ill-posed nature of diffuse fluorescence tomography remains a significant problem for the stability, contrast recovery and spatial resolution of image reconstruction techniques and the optimal approach to FMI in small animals has yet to be agreed on. The majority of research groups have invested in charge-coupled device (CCD)-based systems that provide abundant tissue-sampling but suboptimal sensitivity4-9, while our group and a few others10-13 have pursued systems based on very high sensitivity detectors, that at this time allow dense tissue sampling to be achieved only at the cost of low imaging throughput. Here we demonstrate the methodology for applying single-photon detection technology in a fluorescence tomography system to localize a cancerous brain lesion in a mouse model. The fluorescence tomography (FT) system employed single photon counting using photomultiplier tubes (PMT) and information-rich time-domain light detection in a non-contact conformation11. This provides a simultaneous collection of transmitted excitation and emission light, and includes automatic fluorescence excitation exposure control14, laser referencing, and co-registration with a small animal computed tomography (microCT) system15. A nude mouse model was used for imaging. The animal was inoculated orthotopically with a human glioma cell line (U251) in the left cerebral hemisphere and imaged 2 weeks later. The tumor was made to fluoresce by injecting a fluorescent tracer, IRDye 800CW-EGF (LI-COR Biosciences, Lincoln, NE) targeted to epidermal growth factor receptor, a cell membrane protein known to be overexpressed in the U251 tumor line and many other cancers18. A second, untargeted fluorescent tracer, Alexa Fluor 647 (Life Technologies, Grand Island, NY) was also injected to account for non-receptor mediated effects on the uptake of the targeted tracers to provide a means of quantifying tracer binding and receptor availability/density27. A CT-guided, time-domain algorithm was used to reconstruct the location of both fluorescent tracers (i.e., the location of the tumor) in the mouse brain and their ability to localize the tumor was verified by contrast-enhanced magnetic resonance imaging. Though demonstrated for fluorescence imaging in a glioma mouse model, the methodology presented in this video can be extended to different tumor models in various small animal models potentially up to the size of a rat17.
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影响因子：
3.8
作者：
Lin Y;Barber WC;Iwanczyk JS;Roeck W;Nalcioglu O;Gulsen G
通讯作者：
Gulsen G
影响因子：
--
作者：
Dehghani, Hamid;Eames, Matthew E.;Yalavarthy, Phaneendra K.;Davis, Scott C.;Srinivasan, Subhadra;Carpenter, Colin M.;Pogue, Brian W.;Paulsen, Keith D.
通讯作者：
Paulsen, Keith D.
影响因子：
3.5
作者：
Lin Y;Ghijsen MT;Gao H;Liu N;Nalcioglu O;Gulsen G
通讯作者：
Gulsen G
用于小动物成像的荧光和微计算机断层扫描组合系统
影响因子：
4.6
作者：
Guo, Xiaolian;Liu, Xin;Bai, Jing
通讯作者：
Bai, Jing
影响因子：
3.4
作者：
Tichauer KM;Holt RW;El-Ghussein F;Zhu Q;Dehghani H;Leblond F;Pogue BW
通讯作者：
Pogue BW