生物组织磁聚焦电导率成像原理及反演算法

生物组织磁聚焦电导率成像系统利用多圈螺旋电感线圈形成聚焦磁场激励和检测导电目标,达到了提高成像空间分辨率的目的。根据所推导的频率变化与分层生物组织电导率的关系，引入遗传算法对目标电导率进行反演优化计算，获得了充足的成像数据。对于给定的十层分层生物组织模型，反演优化所得电导率除最深层有较大偏差需要进行数据处理外，其余均与目标一致，成像数据非常可靠；成像速度为百毫秒数量级但是具有很大提高潜力。计算结果表明该方法能够有效地对生物组织进行分层媒质建模计算，进一步采取措施能够实现较高分辨率的实时成像。     

整体器官的光透明成像方法综述

现代光学成像技术与荧光标记技术不断发展,为高分辨地获取生物组织三维结构信息提供了重要的工具。然而,大多数生物组织具有不透明特性,限制了光在组织中的穿透深度,进而限制了光学成像技术在大组织或整体器官成像中的应用。近年兴起的组织光透明技术通过多种物理、化学手段降低组织对光的衰减,增加光穿透深度,从而提高光学成像的成像深度与成像质量,为整体组织器官的三维成像提供了全新的思路。本文从离体组织光透明方法、大组织器官标记方法、三维整体成像技术三个方面,对整体器官的光透明成像方法进行综述。     

OCT技术在生物组织中的应用

基于光学低相干反射测量而发展起来的光学相干层析技术（Ｏｐｔｉｃａｌ Ｃｏｈｅｒｅｎｃｅ Ｔｏｍｏｇｒａｐｈｙ,简称ＯＣＴ）是一种新型的成像技术,它能对高散射介质如生物组织实施非侵入性的快速成像,因而在在体生物组织的微结构分析和疾病诊断等方面有重要应用。本文概述了ＯＣＴ技术在生物组织的成像、特性参数测量、双折射特性测量及流体测速等方面的应用情况。     

光在散射介质中的传输和成像

由于有医学的应用背景,利用红外和近红外波段的光对生物组织进行成像、诊断和治疗是国际上的一个热门课题.而生物组织是高散射介质,本文详细评述了光在散射介质中传输和成像的最新研究动态和进展,并对未来的研究作了展望.     

基于深度学习的多分辨显微关联成像系统设计

显微成像技术作为研究细胞和生物组织的主要工具,对生物医学的发展起到了极大的推动作用。生物样本的复杂化和生物医学领域对时间和空间分辨率的多样化需求决定了单一功能生物成像系统应用的局限性。为满足生物医学领域的多样化需求,解决成像质量与成像时间之间的矛盾,设计了一种基于深度学习的多分辨显微关联成像系统。该系统通过对显微镜进行硬件设计改造和软件处理,将深度学习与关联成像技术有效结合,当采样率仅为60%时,成像系统能够较好地恢复图像细节,大幅降低欠采样带来的噪声,同时显著提升系统成像的时间分辨率。另外,为了满足所设计的小型多分辨显微关联成像系统的实际需求,采用基于重参数化思想的超高效轻量超分网络,在资源受限的设备下实现实时高质量成像。所提出的成像系统可以在保证成像质量的同时显著缩短成像时间和减少内存占用。不同类型生物样本和分辨率板的测试结果进一步表明了系统的鲁棒性和抗噪性能,研究结果对生物医学领域具有重要意义。     

深组织光片荧光显微成像研究进展（特邀）

随着生物医学研究对复杂组织结构和功能的深入探索,高分辨率、高信噪比的深组织成像技术变得愈加重要。传统的显微镜技术往往局限于二维、透明的生物薄样本的观测,这在很大程度上无法满足当前生物医学领域对三维深组织体成像的研究需求。光片荧光显微镜凭借其低光损伤、高采集速率、大视场、体成像等优点被生物学家广泛使用。然而,生物组织固有的高散射特性仍然为深层成像带来了巨大的挑战。本文重点介绍了光片荧光显微成像技术在深组织成像领域的最新进展,特别是应对高散射样本挑战的解决策略,旨在为相关领域的研究人员提供有价值的参考,助力其对该前沿技术的最新进展和应用前景的理解。首先,阐述了光片荧光显微镜的基本原理和高散射吸收特性的形成原因及影响;然后,进一步阐明了增加组织穿透深度、应对光散射和吸收等问题的最新进展;最后,探讨了具有大穿透深度和强抗散射能力的光片荧光显微成像技术的发展前景以及潜在应用。     

自适应光学在双光子显微成像技术中的应用

光学显微镜是生物医学研究必不可少的工具，其中双光子显微成像技术具有大深度三维显微成像功能，被认为是深层生物组织研究的首选工具。但是，在双光子成像系统使用过程中，光学系统的装配偏差、光学元件不理想以及生物样品的不均匀性都会在成像过程中引入像差，从而降低成像质量。通过在双光子显微成像系统中引入自适应光学技术，可实现对像差的有效校正，从而提高成像的分辨率、深度和视场。介绍了双光子显微成像中的像差来源和特点，概述了自适应光学技术中不同的探测和校正方法，综述了近年来自适应光学技术在双光子显微成像中不同的应用成果，最后对自适应光学在双光子显微成像中的发展进行了展望。     

近红外二区荧光成像技术的临床研究进展

近红外荧光成像是外科手术中实现术中导航的关键技术之一。近些年随着近红外二区（NIR-II， 900~1 700 nm）光学生物成像理论的日趋成熟，NIR-II荧光成像技术成为临床手术导航领域的一大研究热点。本文基于NIR-II光学生物成像理论，简要介绍了NIR-II荧光探针及成像系统的发展现状，就NIR-II荧光成像技术在活体小动物手术与人体临床手术中的研究展开综述，讨论了该技术在未来临床手术中的发展潜力以及临床转化中需要面临的难点。     

基于集成成像的生物微小组织三维信息获取方法

提出一种将集成成像和光学显微镜结合实 现生物微小组织三维信息获取的新方法。以显 微镜为基础,结合集成成像特性,应用光学成像理论设计了与光路匹配的微透镜阵列,研制 了微弱光下的 三维信息获取系统。与已有方法相比,本文方法采用新的成像光路和三维信息获取器件,因 而放大倍数更高, 可记录更多的生物微小组织三维信息。针对生物微小组织,利用集成显微成像装置获得了 单元像阵列图像实验数据,分析了样本的三维结构和信息,验证了本文系统在微型组织三维 信息获取方面的有效性。     

无衍射光束在生物显微成像中的应用

无衍射光束近年来广受关注，其无衍射、自修复和自加速的传播特性在微观成像应用中显示出潜在的优势。无衍射特性可抑制光束在传播过程中的衍射，有助于提升成像的分辨率。自修复特性可使光束在透过强散射介质后快速恢复波前，提高成像景深和信噪比。自加速特性可增加光场信息的有效探测维度，实现多维重构成像。本综述结合几类生物显微成像技术特点，介绍以贝塞尔光束、艾里光束为代表的无衍射光束在高分辨生物显微成像中的应用研究进展。     

Molecular Imaging in the Second Near‐Infrared Window

In the past decade, noticeable progress has been achieved regarding fluorescence imaging in the second near‐infrared (NIR‐II) window. Fluorescence imaging in the NIR‐II window demonstrates superiorities of deep tissue penetration and high spatial and temporal resolution, which are beneficial for profiling physiological processes. Meanwhile, molecular imaging has emerged as an efficient tool to decipher biological activities on the molecular and cellular level. Extending molecular imaging into the NIR‐II window would enhance the imaging performance, providing more detailed and accurate information of the biological system. In this progress report, selected achievements made in NIR‐II molecular imaging are summarized. The organization of this report is based on strategies underlying rational designs of NIR‐II imaging probes, and their applications in molecular imaging are highlighted. This progress report may provide guidance and reference for further development of functional NIR‐II probes designed for high‐performance molecular imaging.     

微片激光器移频回馈成像技术及其应用

微片激光器移频回馈成像技术是一种新兴的相干光成像技术,具有灵敏度高、相位可测量、系统结构简单等特点。该项技术可与共聚焦成像、超声调制光学成像、光学合成孔径成像等多种成像技术相结合,在微器件结构测量、生物组织成像、强散射成像等多个领域得到了应用。文章概述了激光器回馈技术的发展过程,详细介绍了微片激光器移频回馈成像技术的理论模型、研究进展及应用情况,并对该技术存在的问题进行了分析。     

Fluorescence lifetime imaging using a diode-pumped all-solid-statelaser system

A whole-field fluorescence lifetime imaging system is presented which is based, for the first time, on an all-solid-state diode-pumped oscillator/amplifier system. Fluorescence lifetime imaging of unstained biological tissue in vitro using this instrument demonstrated contrast between different tissue constituents     

Microwave-tomographic imaging of the high dielectric-contrast objects using different image-reconstruction approaches

Microwave tomography is an imaging modality based on differentiation of dielectric properties of an object. The dielectric properties of biological tissues and its functional changes have high medical significance. Biomedical applications of microwave tomography are a very complicated and challenging problem, from both technical and image reconstruction point-of-views. The high contrast in tissue dielectric properties presenting significant advantage for diagnostic purposes possesses a very challenging problem from an image-reconstruction prospective. Different imaging approaches have been developed to attack the problem, such as two-dimensional (2-D) and three-dimensional (3-D), minimization, and iteration schemes. The goal of this research is to study imaging performance of the Newton and the multiplicative regularized contrast source inversion (MR-CSI) methods in 2-D geometry and gradient and MR-CSI methods in 3-D geometry using high-contrast, medium-size phantoms, and biological objects. Experiments were conducted on phantoms and excised segment of a pig hind-leg using a 3-D microwave-tomographic system operating at frequencies of 0.9 and 2.05 GHz. Both objects being of medium size (10-15 cm) possess high dielectric contrasts. Reconstructed images were obtained using all imaging approaches. Different approaches are evaluated and discussed based on its performance and quality of reconstructed images.     

计算光学成像在散射中的应用

自然界中普遍存在光散射现象。如何通过散射介质实现高分辨率成像是光学成像领域亟待解决的重要问题。在早期研究中,多重光散射被认为是雾霾、云层、生物组织等复杂介质成像中的障碍。然而,最近研究表明,散射并不是成像的基本限制:光子在经过多次散射后仍然包含了大量信息。为了深入了解新兴的计算光学成像是如何解决多重光散射问题的,文中主要介绍了波前整形、散斑相关及深度学习等方法在散射成像领域中的研究进展。最新的研究成果表明:波前整形可以实现动态散射介质内部的高分辨率快速聚焦;散斑相关能够利用单帧散斑实现非侵入式成像;基于深度学习的成像技术能恢复出隐藏在光学厚度为13.4的白色聚苯乙烯平板背后的物体。     

An Integrated Multifunctional Nanoplatform for Deep‐Tissue Dual‐Mode Imaging

The combination of biocompatible superparamagnetic and photoluminescent nanoparticles (NPs) is intensively studied as highly promising multifunctional (magnetic confinement and targeting, imaging, etc.) tools in biomedical applications. However, most of these hybrid NPs exhibit low signal contrast and shallow tissue penetration for optical imaging due to tissue‐induced optical extinction and autofluorescence, since in many cases, their photoluminescent components emit in the visible spectral range. Yet, the search for multifunctional NPs suitable for high photoluminescence signal‐to‐noise ratio, deep‐tissue imaging is still ongoing. Herein, a biocompatible core/shell/shell sandwich structured Fe₃O₄@SiO₂@NaYF₄:Nd³⁺ nanoplatform possessing excellent superparamagnetic and near‐infrared (excitation) to near‐infrared (emission), i.e., NIR‐to‐NIR photoluminescence properties is developed. They can be rapidly magnetically confined, allowing the NIR photoluminescence signal to be detected through a tissue as thick as 13 mm, accompanied by high T₂ relaxivity in magnetic resonance imaging. The fact that both the excitation and emission wavelengths of these NPs are in the optically transparent biological windows, along with excellent photostability, fast magnetic response, significant T₂‐contrast enhancement, and negligible cytotoxicity, makes them extremely promising for use in high‐resolution, deep‐tissue dual‐mode (optical and magnetic resonance) in vivo imaging and magnetic‐driven applications.     

自适应光学高分辨率共聚焦显微成像技术

生物样品折射率的空间变化导致了光学畸变的产生,这种畸变对于共聚焦显微镜观察厚的生物样品和活体体内组织成像是一种严重的限制。自适应光学(AO)技术是通过快速反应的变形镜使镜面发生形变来补偿像差,在共聚焦显微镜中应用自适应光学技术可以校正光学畸变,观察深层组织活动,进行活体成像和实时检测。详细分析了共聚焦显微镜中像差的来源及光学畸变的特点,讨论了目前在共聚焦显微镜中自适应光学校正的方案及研究现状,讨论了共聚焦显微镜中自适应光学的波前传感器、畸变测量和波前校正器,并探讨了目前超高分辨率显微成像技术的发展方向。     

Microlenses Fabricated by Two-Photon Laser Polymerization for Cell Imaging with Non-Linear Excitation Microscopy

Non-linear excitation microscopy offers several advantages for in-vivo imaging compared to conventional confocal techniques. However, tissue penetration can still be an issue due to scattering and spherical aberrations induced on focused beams by the tissue. The use of low numerical aperture objectives to pass through the outer layers of the skin, together with high dioptric power microlenses implanted in-vivo close to the observation volume, can be beneficial to the reduction of optical aberrations. Here, Fibroblast cell culture plano-convex microlenses to be used for non-linear imaging of biological tissue are developed and tested. The microlenses can be used as single lenses or multiplexed in an array. A thorough test of the lenses wavefront is reported together with the modulation transfer function and wavefront profile. Magnified fluorescence images can be retrieved through the microlenses coupled to commercial confocal and two-photon excitation scanning microscopes. The signal-to-noise ratio of the images is not substantially affected by the use of the microlenses and the magnification can be adjusted by changing the relative position of the microlens array to the microscope objective and the immersion medium. These results are opening the way to the application of implanted micro-optics for optical in-vivo inspection of biological processes.     

Stimuli-Responsive Organic Near-Infrared Photoacoustic Probes

Photoacoustic (PA) imaging is an emerging biomedical imaging technique with the features of non-invasiveness and non-ionization. It takes advantage of the photothermal effect of PA probes to convert absorbed photon energy into heat and subsequent transient thermoelastic tissue expansion for ultrasonic waves for PA images. Thus, PA imaging exhibits the combined superiority of high-contrast optical imaging and deep tissue penetration of acoustic imaging, which furnishes high-resolution and high-contrast tissue images. Stimuli-responsive organic PA agents in the near-infrared (NIR) biological window have attracted increasing attention because of their low biological toxicity and response characteristics. This review focuses on the recent research progress of stimuli-responsive organic NIR probes for PA imaging, including the temperature response, pH response, redox response, metal ion response, and enzyme response. And the stimuli-responsive mechanisms are highlighted in detail. Moreover, their perspectives and challenges are discussed. It will be of great help for the further development of organic NIR PA probes with stimuli-response.