光学分子影像学技术在肿瘤中的应用进展

分子影像学技术是一种在活体状态下从微观上显示组织、细胞及亚细胞水平的影像技术,具有实时、无创、精准及灵敏等特点,可在细胞和分子水平进行肿瘤早期筛查和诊断。随着生物发光与荧光成像技术的进步,光学分子影像学技术快速发展。本文就光学分子影像学技术在肿瘤中的应用进展进行综述。     

分子影像学:前沿技术及应用研究

近年来,随着纳米生物医学的进步和光学成像技术的兴起,分子影像学呈现出与材料学、化学、医用物理学、生物医学工程和基因组学等多个学科紧密融合的发展态势,基于纳米技术的新型分子显像剂迅速发展,以小分子、肽、抗体和适体修饰的纳米粒子已广泛应用于临床前研究和临床转化,分子影像技术在临床诊疗中有重大突破并取得一系列研究成果。多模态分子成像技术在精准诊疗中崭露头角,新一轮成像技术的升级能获取更多组织和分子层面的信息,进一步促进学科之间的交叉融合。本文着重从光学和光声分子影像、磁共振分子影像和正电子发射断层扫描分子影像3个方面的前沿技术和临床应用做一综述。      

纳米分子影像学

纳米科学与分子影像学的结合可形成纳米分子影像学(Nanomolecular imaging).纳米分子影像学从广义上是指在纳米转运体(纳米粒转运载体)介导下,应用分子影像学技术对活体生物化学过程进行细胞和分子水平上的定性和定量研究的一门科学,主要包括磁共振纳米分子影像学、光学纳米分子影像学、核医学纳米分子影像学和超声纳米分子影像学.本文主要阐述纳米分子影像学的理论基础、技术方法及潜在的应用价值.     

心血管疾病基因治疗的分子影像学研究进展

近年来,利用基因治疗心血管疾病的实验与临床前期研究取得了较快的发展.分子影像学是在分子或细胞水平上研究活体生命或疾病过程的特定分子事件的新技术,为心血管疾病的基因治疗提供了一种实时、无创地检测方法,促进了这一治疗模式的发展和完善.本文主要综述分子影像学在心血管疾病基因治疗中的应用,包括分子探针、成像技术(包括核医学、MRI、超声、光学成像)的进展.     

液态氟碳纳米粒在超声分子靶向成像及治疗中的研究进展

随着超声分子影像学技术的发展,液态氟碳纳米粒作为构建超声分子探针的新型材料,在超声分子靶向成像及治疗的研究中表现出良好的应用前景,是一种非常具有潜力的超声分子探针,有望实现超声分子影像技术对疾病的精准诊断及治疗。本文对液态氟碳纳米粒在超声分子靶向成像及治疗中的研究进展进行综述。     

光声成像分子造影剂

光声成像是利用光声效应成像的新型影像技术, 具有光学成像高对比度和超声成像高穿透力的优势。光声成像分子包括内源性生色团和外源性造影剂, 其中外源性分子造影剂的应用, 使分子光声成像成为可能, 因而具有广阔的生物医学应用前景及重要的研究意义。本文对光声成像外源性分子造影剂的物理化学性质及合成方式进行综述, 重点介绍小分子有机染料、贵金属纳米颗粒、碳纳米材料、有机纳米多聚物、基因编码的生色团、铜铁化合物、半导体多聚物纳米颗粒等光声信号复合物及常见的配体分子, 如小分子、肽类、亲和小体、适体和抗体等, 并对未来本领域的相关研究进行展望。     

以纳米分子探针为基础的分子影像技术在肿瘤早期检测中的应用

包含纳米材料、纳米器件以及纳米表征测量等的纳米技术,对生物、医学的进步产生了巨大影响.尤其利用纳米材料独特的颗粒及光学、电学等特性,结合现代医学影像技术,如光学成像、CT、PET/SPECT、MRI及超声成像(US)等,有可能在肿瘤发生初期进行早期特异性检测和有效的靶向治疗,使影像医学从对传统的解剖和生理功能的研究进展到分子水平成像,实现靶向分子成像,探索疾病的分子水平变化,在疾病早期做出明确诊断.     

腹部术中输尿管实时识别研究进展

在腹部外科手术过程中,医源性输尿管损伤虽然较罕见,但是一旦发生损伤将会产生严重的并发症,如腹腔感染、输尿管瘘、肾衰竭等。为了降低腹部术中医源性输尿管损伤的风险,术中实时在体输尿管可视化的医学成像技术被广泛地研究与应用,如预防输尿管导管置入术（或发光输尿管支架置入术）、gamma探测技术、荧光成像技术。然而这些技术目前仅有荧光成像技术可以达到无创、无电离辐射、可实时在体获取输尿管的位置信息。相关研究已证实了应用荧光成像技术结合外源荧光染料的使用在腹部术中实时在体可视化输尿管位置信息的可行性,并取得重要的进展。本文就近年来应用荧光成像技术和外源荧光染料（荧光素钠、亚甲基蓝、吲哚、CW800-CA、ZW800-1）在腹部术中输尿管实时识别的研究进展做一综述。      

多模态超声分子影像探针的研究进展

近年来,多模态超声分子影像技术发展迅速,其核心是构建以多功能超声造影剂为基础,并可同时用于光学、MRI、CT、PET等多种影像学技术成像的超声分子探针。目前,国内外学者利用不同材料对构建多模态超声造影剂进行了大量尝试,本文在上述研究的基础上,对构建材料的优缺点及其应用前景进行综述。     

分子影像学的研究范畴及其进展

分子影像学的成像基础是生物体的细胞,都含有水、无机盐、离子和碳水化合物或有机小分子等小分子物质和蛋白质、糖类、脂类、核酸等大分子物质.机体内直接调节细胞生命活动的信息分子分为三种:局部化学介质、激素和神经递质.实现真正意义上的分子影像学技术的三大要素为分子探针、信号放大和高灵敏探测仪.分子影像学利用分子探针→插入人体细胞内→遇到特定基因产物或特定分子时→发射信号→PET、MRI、CT、光学成像仪或红外线记录其信号→显示其分子图像、代谢图像、基因转变图像.     

Improved detection limits using a hand-held optical imager with coregistration capabilities

Optical imaging is emerging as a non-invasive and non-ionizing method for breast cancer diagnosis. A hand-held optical imager has been developed with coregistration facilities towards flexible imaging of different tissue volumes and curvatures in near real-time. Herein, fluorescence-enhanced optical imaging experiments are performed to demonstrate deeper target detection under perfect and imperfect (100:1) uptake conditions in (liquid) tissue phantoms and in vitro. Upon summation of multiple scans (fluorescence intensity images), fluorescent targets are detected at greater depths than from single scan alone.     

Label free measurement of retinal blood cell flux,velocity, hematocrit and capillary width in the living mouse eye

Measuring blood cell dynamics within the capillaries of the living eye provides crucial information regarding the health of the microvascular network. To date, the study of single blood cell movement in this network has been obscured by optical aberrations, hindered by weak optical contrast, and often required injection of exogenous fluorescent dyes to perform measurements. Here we present a new strategy to non-invasively image single blood cells in the living mouse eye without contrast agents. Eye aberrations were corrected with an adaptive optics camera coupled with a fast, 15 kHz scanned beam orthogonal to a capillary of interest. Blood cells were imaged as they flowed past a near infrared imaging beam to which the eye is relatively insensitive. Optical contrast of cells was optimized using differential scatter of blood cells in the split-detector imaging configuration. Combined, these strategies provide label-free, non-invasive imaging of blood cells in the retina as they travel in single file in capillaries, enabling determination of cell flux, morphology, class, velocity, and rheology at the single cell level.OCIS codes: (170.4460) Ophthalmic optics and devices, (330.4300) Vision system - noninvasive assessment, (110.1080) Active or adaptive optics, (330.7324) Visual optics, comparative animal models     

Deep-Tissue Reporter-Gene Imaging with Fluorescence and Optoacoustic Tomography: A Performance Overview

Purpose

A primary enabling feature of near-infrared fluorescent proteins (FPs) and fluorescent probes is the ability to visualize deeper in tissues than in the visible. The purpose of this work is to find which is the optimal visualization method that can exploit the advantages of this novel class of FPs in full-scale pre-clinical molecular imaging studies.

Procedures

Nude mice were stereotactically implanted with near-infrared FP expressing glioma cells to from brain tumors. The feasibility and performance metrics of FPs were compared between planar epi-illumination and trans-illumination fluorescence imaging, as well as to hybrid Fluorescence Molecular Tomography (FMT) system combined with X-ray CT and Multispectral Optoacoustic (or Photoacoustic) Tomography (MSOT).

Results

It is shown that deep-seated glioma brain tumors are possible to visualize both with fluorescence and optoacoustic imaging. Fluorescence imaging is straightforward and has good sensitivity; however, it lacks resolution. FMT-XCT can provide an improved rough resolution of ～1 mm in deep tissue, while MSOT achieves 0.1 mm resolution in deep tissue and has comparable sensitivity.

Conclusions

We show imaging capacity that can shift the visualization paradigm in biological discovery. The results are relevant not only to reporter gene imaging, but stand as cross-platform comparison for all methods imaging near infrared fluorescent contrast agents.     

Wound healing monitoring using near infrared fluorescent fibrinogen

We demonstrate a method for imaging the wound healing process with near infrared fluorescent fibrinogen. Wound healing studies were performed on a rat punch biopsy model. Fibrinogen was conjugated with a near infrared fluorescent dye and injected into the tail vein. Fibrinogen is a useful protein for tracking wound healing because it is involved in fibrin clot formation and formation of new provisional matrix through transglutaminase's crosslinking activity. Strong fluorescence specific to the wound was observed and persisted for several days, indicating that the fibrinogen is converted to crosslinked fibrin. Administration of contrast agent simultaneously with wound creation led to primary labeling of the fibrin clot, indicating that the wound was in its early phase of healing. Administration on the following day showed labeling on the wound periphery, indicating location of formation of a new provisional matrix. This method may prove to be useful as a diagnostic for basic studies of the wound healing process, in drug development, or in clinical assessment of chronic wounds.     

Fluoromodule-based reporter/probes designed for in vivo fluorescence imaging

Optical imaging of whole, living animals has proven to be a powerful tool in multiple areas of preclinical research and has allowed noninvasive monitoring of immune responses, tumor and pathogen growth, and treatment responses in longitudinal studies. However, fluorescence-based studies in animals are challenging because tissue absorbs and autofluoresces strongly in the visible light spectrum. These optical properties drive development and use of fluorescent labels that absorb and emit at longer wavelengths. Here, we present a far-red absorbing fluoromodule–based reporter/probe system and show that this system can be used for imaging in living mice. The probe we developed is a fluorogenic dye called SC1 that is dark in solution but highly fluorescent when bound to its cognate reporter, Mars1. The reporter/probe complex, or fluoromodule, produced peak emission near 730 nm. Mars1 was able to bind a variety of structurally similar probes that differ in color and membrane permeability. We demonstrated that a tool kit of multiple probes can be used to label extracellular and intracellular reporter–tagged receptor pools with 2 colors. Imaging studies may benefit from this far-red excited reporter/probe system, which features tight coupling between probe fluorescence and reporter binding and offers the option of using an expandable family of fluorogenic probes with a single reporter gene.     

Deconvolution techniques for experimental optical imaging in medicine

Optical imaging in biomedicine is essentially determined by the light absorption and scattering interaction of microscopic and macroscopic constituents in the medium. In the near infrared range (NIR) the scattering event, with a coefficient approximately two orders of magnitude greater than absorption, plays a dominant role. The size of the detected scattered light volume is apparently larger than the original one. The purpose of this paper is to quantify these effects for fluorescent light. To this effect, the optical properties of dental composite phantoms were measured and the blurring of a point source – referred to as generalized point spread function (PSF) – was calculated by Monte Carlo simulations. We demonstrate the use of this method for scaling the concentration of fluorophores and for reconstruction of the true shape of fluorescence regions below the scattering layer of the phantom by deconvolution. The combination of these two mathematical techniques – construction of the PSF by Monte Carlo simulation (MCS) and deconvolution of the stray light picture – is of benefit for the interpretation of fluorescence and scattering images used for various medical applications.     

E‐selectin targeting to visualize tumorsin vivo

Generally angiogenic factors induce the expression of E‐selectin in vascular endothelial cells in the tumors. In this study, we employed an anti‐E‐selectin monoclonal antibody to target tumors in vivo and evaluated an optical imaging reagent to visualize tumor regions. The anti‐E‐selectin antibody was conjugated on the surface of liposomes, which encapsulated the near‐infrared fluorescent substances Cy3 or Cy5.5. The liposomes efficiently recognized human umbilical vein endothelial cells only when E‐selectin was induced by angiogenic factors such as TNF‐α in vitro. Cy5.5 encapsulated into liposomes that were conjugated with an anti‐E‐selectin antibody successfully visualized Ehrlich ascites tumor cells when transplanted into mice. Thus, E‐selectin targeting with liposomes containing a near‐infrared fluorescent dye was found effective in visualizing tumors in vivo. This strategy should be extremely useful as a method to identify sentinel lymphatic nodes and angiogenic tumors as well as use for drug delivery to tumor cells. Copyright © 2010 John Wiley & Sons, Ltd.     

近红外荧光分子探针用于CT成像及术中导航

目的 制备近红外荧光分子探针,观察其用于增强CT成像及术中导航效果。方法 采用薄膜水化法制备载IR780和全氟溴辛烷(PFOB)的脂质体(IR780@LIP-PFOB),检测其基本理化性质,观察其用于增强体内、外CT成像的效果。以激光共聚焦显微镜和流式细胞仪观察4T1细胞对IR780@LIP-PFOB的摄取情况,以活体荧光成像检测IR780@LIP-PFOB在荷4T1瘤BALB/c小鼠体内的分布,通过冰冻切片观察IR780@LIP-PFOB在肿瘤区和周围非瘤组织的分布;以实时体视荧光成像系统评估IR780@LIP-PFOB用于术中导航的效能。结果 所获IR780@LIP-PFOB大小均匀,呈球形,平均粒径(262.80±117.60)nm,表面电位(－20.10±6.38)mV,IR780包封率为82.92%;用于小鼠体内、外CT可显著增强成像效果。IR780@LIP-PFOB可选择性聚集于4T1细胞周围并于肿瘤区富集,而非瘤组织中未见其明显聚集;用于术中导航可清晰辨识肿瘤组织及其边界。结论 成功制备的近红外荧光分子探针用于小鼠能增强CT成像效果,并支持术中导航。     

Optical imaging of subacute airway remodeling and adipose stem cell engraftment after airway injury

Acquired airway injury is frequently caused by endotracheal intubations, long-term tracheostomies, trauma, airway burns, and some systemic diseases. An effective and less invasive technique for both the early assessment and the early interventional treatment of acquired airway stenosis is therefore needed. Optical coherence tomography (OCT) has been proposed to have unique potential for early monitoring from the proliferative epithelium to the cartilage in acute airway injury. Additionally, stem cell therapy using adipose stem cells is being investigated as an option for early interventional treatment in airway and lung injury. Over the past decade, it has become possible to monitor the level of injury using OCT and to track the engraftment of stem cells using stem cell imaging in regenerative tissue. The purpose of this study was to assess the engraftment of exogenous adipose stem cells in injured tracheal epithelium with fluorescent microscopy and to detect and monitor the degree of airway injury in the same tracheal epithelium with OCT. OCT detected thickening of both the epithelium and basement membrane after tracheal scraping. The engraftment of adipose stem cells was successfully detected by fluorescent staining in the regenerative epithelium of injured tracheas. OCT has the potential to be a high-resolution imaging modality capable of detecting airway injury in combination with stem cell imaging in the same tracheal mucosa.OCIS codes: (170.6935) Tissue characterization, (170.3880) Medical and biological imaging, (170.1610) Clinical applications, (170.4500) Optical coherence tomography     

Single-scan HiLo with line-illumination strategy for optical section imaging of thick tissues

Optical sectioning has been widely employed for inhibiting out-of-focus backgrounds in three-dimensional (3D) imaging of biological samples. However, point scanning imaging or multiple acquisitions for wide-field optical sectioning in epi-illumination microscopy remains time-consuming for large-scale imaging. In this paper, we propose a single-scan optical sectioning method based on the hybrid illumination (HiLo) algorithm with a line-illumination strategy. Our method combines HiLo background inhibition with confocal slit detection. It thereby offers a higher optical sectioning capability than wide-field HiLo and line-confocal imaging without extra modulation and multiple data acquisition. To demonstrate the optical-sectioning capability of our system, we imaged a thin fluorescent plane and different fluorescence-labeled mouse tissue. Our method shows an excellent background inhibition in thick tissue and thus potentially provides an alternative tool for 3D imaging of large-scale biological tissue.