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分子影像学是医学影像技术和分子生物学、化学、物理学、放射医学、核医学以及计算机科学相结合的一门新的学科,由Weissleder[1]教授于1999年首先提出,即应用影像学的方法对活体状态下的生物过程进行细胞和分子水平的定性和定量研究。它主要是以体内特定分子为成像对比度源,利用现有的一些医学影像技术对人体内部生理或病理过程在分子水平上进行无损伤、实时的成像,并且将遗传基因信息、生物化学与新的成像探针进行综合,由精密的成像技术来检测,再通过一系列的图像后处理技术,达到在分子和细胞水平上显示活体组织的生物学过程的目的。医学成像模式总体可以划分为两大类:一种是解剖成像,即产生形态学图像,包括X射线成像、CT、MRI、超声成像(ultrasonic imaging, US)以及各类内镜成像(如腹腔镜、喉镜、电子胃镜等)等,它以高分辨率提供了组织器官的解剖形态信息;另一种是功能成像,包括PET、SPECT、功能MRI等,它可以提供组织器官的代谢信息[2]。表 1列出了几种不同的分子影像技术的基本信息及其优缺点[3]。通过这些成像技术,可以活体检测特定分子的活动(如蛋白酶和水解酶的活动)、生物学过程(如细胞凋亡、受体活动、抗原修饰、报告基因表达、血管生成、肿瘤转移)、肿瘤的诊治(如早期诊断、检测、个体化治疗以及抗癌药物的筛选研发)等[4]。
显像方法 基础原理 分辨率 采集时间 优点 缺点 生物发光成像 可见光 1~10 mm 数分钟 高灵敏度,无辐射,可评价细胞存活功能 分辨率低,只能浅表成像,二维影像 荧光成像 可见光、近红外光 1~10 mm 数秒钟至数分钟 高灵敏度,无辐射,显像过程简便快捷 随组织深度增加,衰减较多,只能浅表成像;发射波长<600 nm时,易于受自发荧光干扰 PET 高能γ射线 1~2 mm 数分钟 高灵敏度,可定量分析 需要加速器生产,短半衰期核素,有放射辐照 SPECT 低能γ射线 1~2 mm 数分钟 高灵敏度 有放射辐照,灵敏度较PET低,分辨率低 MRI 无线电波 25~100 μm 数分钟至数小时 最高的空间分辨率,功能成像 灵敏度低,图像采集、重建处理时间长 CT X射线+对比剂 50 μm 数分钟 良好的分辨率 较低的软组织对比度,有放射辐照 表 1 几种不同分子影像技术的基本信息及其优缺点对比
Table 1. The basic information of the several different molecular imaging techniques and their advantages and disadvantages
树枝状聚合物在双模态分子影像探针制备中的作用及研究进展
The function and research progress of dendrimer on preparing bimodal molecular imaging probe
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摘要: 随着医疗水平的不断提高,人们对疾病的早期诊断和准确定位的要求越来越高。近年来,PET/CT和SPECT/CT已广泛应用于临床。为了能够在早期精确诊断的同时准确定位病灶,双模态成像方式备受科研人员和临床工作者的关注。双模态分子影像学的发展除了需要先进的成像设备外,最关键的是开发新型且高效的双模态成像探针。树枝状高分子纳米材料由于其结构均一,粒径可控,同时表面具有大量活性基团可用于连接多种分子探针,是一类潜在的双模态分子探针载体。该文就树枝状聚合物作为双模态探针载体,在光学成像/MRI、SPECT/CT及CT/MRI等成像领域中的应用研究进行相关的介绍。Abstract: With the continuous improvement of the recent medical, people′s demand for the early diagnosis and accurate localization of the disease have been increased. Recently, the PET/CT and SPECT/CT have been widely used in clinic. In order to accurately locate lesions and diagnose the disease at the same time, the bimodal molecular imaging have been widely concerned by the researchers and clinical scientists. Other than the advanced imaging equipment, the most important for the bimodal molecular imaging is to develop new and efficient bimodal molecular imaging probes. Dendrimer nanomaterial is a potential bimodal molecular imaging probe vector because of its uniform structure, controllable particle size, and meanwhile the surface with a large number of active groups which can be used to connect multiple molecular probes. This paper introduced the application of dendrimer nanomaterial used as bimodal molecular imaging probe vector in optical imaging/MRI, SPECT/CT and CT/MRI.
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Key words:
- Bimodal molecular imaging /
- Dendrimer /
- Nanocarriers
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表 1 几种不同分子影像技术的基本信息及其优缺点对比
Table 1. The basic information of the several different molecular imaging techniques and their advantages and disadvantages
显像方法 基础原理 分辨率 采集时间 优点 缺点 生物发光成像 可见光 1~10 mm 数分钟 高灵敏度,无辐射,可评价细胞存活功能 分辨率低,只能浅表成像,二维影像 荧光成像 可见光、近红外光 1~10 mm 数秒钟至数分钟 高灵敏度,无辐射,显像过程简便快捷 随组织深度增加,衰减较多,只能浅表成像;发射波长<600 nm时,易于受自发荧光干扰 PET 高能γ射线 1~2 mm 数分钟 高灵敏度,可定量分析 需要加速器生产,短半衰期核素,有放射辐照 SPECT 低能γ射线 1~2 mm 数分钟 高灵敏度 有放射辐照,灵敏度较PET低,分辨率低 MRI 无线电波 25~100 μm 数分钟至数小时 最高的空间分辨率,功能成像 灵敏度低,图像采集、重建处理时间长 CT X射线+对比剂 50 μm 数分钟 良好的分辨率 较低的软组织对比度,有放射辐照 -
[1] Weissleder R. Molecular imaging: exploring the next frontier[J]. Radiology, 1999, 212(3): 609-614. doi: 10.1148/radiology.212.3.r99se18609 [2] 王江涛, 韩萍.医学图像融合的临床应用与新进展[J].医学影像学杂志, 2009, 19(4): 476-478.
[3] 赵倩, 李娟, 王荣福. PET/MRI现象技术与其他分子影像技术的比较[J].中国医学装备, 2013, 10(1): 4-7.
[4] Pysz MA, Gambhir SS, Willmann JK. Molecular imaging: current status and emerging strategies[J]. Clin Radiol, 2010, 65(7): 500-516. doi: 10.1016/j.crad.2010.03.011 [5] Lee S, Chen X. Dual-modality probes for in vivo molecular imaging[J]. Mol Imaging, 2009, 8(2): 87-100. [6] 黄佳国, 曾文彬, 周明, 等.双模态分子影像探针研究进展[J].生物物理学报, 2011, 27(4): 301-311.
[7] Ma N, Ma C, Deng Y, et al. Advances in applications of dendritic compounds[J]. J Nanosci Nanotechnol, 2013, 13(1): 33-39. doi: 10.1166/jnn.2013.6697 [8] Koga T, Iimura M, Higashi N. Novel peptide-shelled dendrimer with dramatically changeable thermo-responsive character[J]. Macromol Biosci, 2012, 12(8): 1043-1047. doi: 10.1002/mabi.201100509 [9] Lo ST, Kumar A, Hsieh JT, et al. Dendrimer nanoscaffolds for potential theranostics of prostate cancer with a focus on radiochemistry[J]. Mol Pharm, 2013, 10(3): 793-812. doi: 10.1021/mp3005325 [10] Caminade AM, Laurent R, Zablocka M, et al. Organophosphorus chemistry for the synthesis of dendrimers[J]. Molecules, 2012, 17(11): 13605-13621. doi: 10.3390/molecules171113605 [11] Yamamoto A. Improvement of intestinal absorption of poorly absorbable drugs by polyamidoamine(PAMAM)dendrimers as novel absorption enhancers[J]. Yakugaku Zasshi, 2010, 130(9): 1123-1127. doi: 10.1248/yakushi.130.1123 [12] Jiang YY, Tang GT, Zhang LH, et al. PEGylated PAMAM dendrimers as a potential drug delivery carrier: in vitro and in vivo comparative evaluation of covalently conjugated drug and noncovalent drug inclusion complex[J]. J Drug Target, 2010, 18(5): 389-403. doi: 10.3109/10611860903494203 [13] Tomalia DA, Reyna LA, Svenson S. Dendrimers as multi-purpose nanodevices for oncology drug delivery and diagnostic imaging[J]. Biochem Soc Trans, 2007, 35(Pt 1): 61-67. [14] 陈铨, 张永学.分子成像技术的研究进展[J].国际放射医学核医学杂志, 2011, 35(5): 290-295.
[15] Boswell CA, Eck PK, Regino CA, et al. Synthesis, characterization, and biological evaluation of integrin alphavbeta3-targeted PAMAM dendrimers[J]. Mol Pharm, 2008, 5(4): 527-539. doi: 10.1021/mp800022a [16] Chen WT, Thirumalai D, Shih TT, et al. Dynamic contrast-enhanced folate-receptor-targeted MR imaging using a Gd-loaded PEG-dendrimer-folate conjugate in a mouse xenograft tumor model[J]. Mol Imaging Biol, 2010, 12(2): 145-154. [17] Ali MM, Bhuiyan MP, Janic B, et al. A nano-sized PARACEST-fluorescence imaging contrast agent facilitates and validates in vivo CEST MRI detection of glioma[J]. Nanomedicine(Lond), 2012, 7(12): 1827-1837. [18] Kosaka N, Bernardo M, Mitsunaga M, et al. MR and optical imaging of early micrometastases in lymph nodes: triple labeling with nano-sized agents yielding distinct signals[J]. Contrast Media Mol Imaging, 2012, 7(2): 247-253. doi: 10.1002/cmmi.489 [19] Franc BL, Acton PD, Mari C, et al. Small-animal SPECT and SPECT/CT: important tools for preclinical investigation[J]. J Nucl Med, 2008, 49(10): 1651-1663. doi: 10.2967/jnumed.108.055442 [20] Criscione JM, Dobrucki LW, Zhuang ZW, et al. Development and application of a multimodal contrast agent for SPECT/CT hybrid imaging[J]. Bioconjug Chem, 2011, 22(9): 1784-1792. doi: 10.1021/bc200162r [21] Parrott MC, Benhabbour SR, Saab C, et al. Synthesis, radiolabeling, and bio-imaging of high-generation polyester dendrimers[J]. J Am Chem Soc, 2009, 131(8): 2906-2916. doi: 10.1021/ja8078175 [22] Regino CA, Walbridge S, Bernardo M, et al. A dual CT-MR dendrimer contrast agent as a surrogate marker for convection-enhanced delivery of intracerebral macromolecular therapeutic agents[J]. Contrast Media Mol Imaging, 2008, 3(1): 2-8. [23] Wen S, Li K, Cai H, et al. Multifunctional dendrimer-entrapped gold nanoparticles for dual mode CT/MR imaging applications[J]. Biomaterials, 2013, 34(5): 1570-1580. doi: 10.1016/j.biomaterials.2012.11.010 [24] Li K, Wen S, Larson AC, et al. Multifunctional dendrimer-based nanoparticles for in vivo MR/CT dual-modal molecular imaging of breast cancer[J]. Int J Nanomedicine, 2013, 8: 2589-2600. [25] Chen Q, Li K, Wen S, et al. Targeted CT/MR dual mode imaging of tumors using multifunctional dendrimer-entrapped gold nanoparticles[J]. Biomaterials, 2013, 34(21): 5200-5209. doi: 10.1016/j.biomaterials.2013.03.009 [26] Akhter S, Ahmad I, Ahmad MZ, et al. Nanomedicines as cancer therapeutics: current status[J]. Curr Cancer Drug Targets, 2013, 13(4): 362-378. doi: 10.2174/1568009611313040002 [27] Alavidjeh MS, Haririan I, Khorramizadeh MR, et al. Anionic linear-globular dendrimers: biocompatible hybrid materials with potential uses in nanomedicine[J]. J Mater Sci Mater Med, 2010, 21(4): 1121-1133. doi: 10.1007/s10856-009-3978-8