A promising approach for quantifying focal stroke modeling and assessing stroke progression:optical resolution photoacoustic microscopy photothrombosis

To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these methods often require complex systems and the effect of age on cerebral embolism has not been adequately studied,although ischemic stroke is strongly age-related.In this study,we propose an optical-resolution photoacoustic microscopy-based visualized photothrombosis methodology to create and monitor ischemic stroke in mice simultaneously using a 532 nm pulsed laser.We observed the molding process in mice of different ages and presented age-dependent vascular embolism differentiation.Moreover,we integrated optical coherence tomography angiography to investigate age-associated trends in cerebrovascular variability following a stroke.Our imaging data and quantitative analyses underscore the differential cerebrovascular responses to stroke in mice of different ages,thereby highlighting the technique's potential for evaluating cerebrovascular health and unraveling age-related mechanisms involved in ischemic strokes.

Multidither coherent optical adaptive technique for deep tissue two-photon microscopy

Two-photon microscopy normally suffers from the scattering of the tissue in biological imaging.Multidither coberent optical adaptive technique(COAT)can correct the scattered wavefront in parallel.However,the determination of the corrective phases may not be completely accurate using conventional method,which undermines the performance of this technique.In this paper,we theoretically demonstrate a method that can obtain more accurate corrective phases by determining the phase values from the square root of the fuorescence signal.A numnerical simulation model is established to study the performance of adaptive optics in two-photon micros-copy by combining scalar diffraction theory with vector diffraction theory.The results show that the distortion of the wavefront can be corrected more thoroughly with our method in two-photon imaging.In our simulation,with the scattering from a 450-mn-thick mouse brain tissue,excitation focal spots with higher peak-to background ratio(PBR)and images with higher contrast can be obtained.Hence,further enhancement of the multidither COAT correction performance in two-photon imaging can be expected.

In vivo evaluation of laser-induced choroidal neovascularization in rats simultaneously using optical coherence tomography and photoacoustic microscopy

Determination of the precise location and the degree of the Choroidal neovascularization(CNV)lesion is essential for diagnosation Neovascular age-related macular degeneration(AMD)and evaluation the efficacy of treatment.Noninvasive imaging techniques with specific contrast for CNV evaluation are demanded.In this paper,two noninvasive imaging techniques,namely Optical coherence tomography(OCT)and Photoacoustic microscopy(PAM),are combined to provide specific detection of CNV for their complimentary contrast mechanisms.In vivo time-serial evaluation of Laser-induced CNV in rats is present at days 1,3,5,7,14,21 after laser photocoagulation is applied to the rat fundus.Both OCT and PAM show that the CNV increases to its maximum at day 7 and decreases at day 14.Quantification of CNV area and CNV thickness is given.The dual-modal information of CNV is consistent with the histologic evaluation by hematoxylin and eosin(H&E)staining.

High-speed all-optic optical coherence tomography and photoacoustic microscopy dual-modal system for microcirculation evaluation

We propose a high-speed all-optic dual-modal system that integrates spectral domain optical coherence tomography and photoacoustic microscopy(PAM).A 3*3 coupler-based interfer-ometer is used to remotely detect the surface vibration caused by photoacoustic(PA)waves.Three outputs of the interferometer are acquired simultaneously with a multi-channel data ac-quisition card.One channel data with the highest PA signal detection sensitivity is selected for sensitivity compensation.Experiment on the phantom demonstrates that the proposed method can sucessfully compensate for the loss of intensity caused by sensitivity variation.The imaging speed of the PAM is improved compared to our previous system.The total time to image a sample with 256×256 pixels is~20s.Using the proposed system,the microvasculature in the mouse auricle is visualized and the blood flow state is accessed.

Intravital imaging of adriamycin-induced renal pathology using two-photon microscopy and optical coherence tomography

Adriamycin(doxorubicin),a common cancer chemotherapeutic drug,can be used to induce a model of chronic progressive glomerular disease in rodents.In our studies,we evahuated renal changes in a rat model after Adriamydin injection using two photon microscopy(TPM),optical coherence tomography(OCT)and Doppler OCT(DOCT).Taking advantage of deep penetra-tion and fast scanning speed for three dimensional(3D)label-free imaging,OCT/DOCT system was able to reveal glomerular and tubular pathology noninvasively and in real time.By imaging renal pathology following the infusion of fAuorophore-labeled dextrans of different molecular weights,TPM can provide direct views of glomerular and tubular flow dynamics with the onset and progression of renal disease.Specifically,glomerular permeability and filtration,proximal and distal tubular flow dynamics can be revealed.6-8 weeks after injection of Adriamycin,TPM and OCT/DOCT imaging revealed glomerular sclerosis,compromised flow across the glomerular wall,tubular atrophy,tubular dilation,and variable intra-tubular flow dynamics.Our results indicate that TPM and OCT/DOCT provide real-time imaging of renal pathology in vivo that has not been previously available using conventional microscopic procedures.

Internal Defect Measurement of Scattering Media by Optical Coherence Microscopy

Optical coherence microscopy is applied to measure scattering media'sinternal defect, which based on low coherence interferometry and confocal microscopy. Opticalcoherence microscopy is more effective in the rejection of out of focus and multiple scatteredphotons originating further away of the focal plane. With the three-dimension scanning, the internaldefect is detected by measuring the thickness of different points on the sample. The axialresolution is 6 μm and lateral resolution is 1. 2 μm. This method is possessed of the advantagesover the other measurement method of scattering media, such as non-destruction and high-resolution.

Advanced optical microscopy methods for in vivo imaging of sub-cellular structures in thick biological tissuesl

Optical microscopy has become an indispensable tool for visualizing sub-cellular structures andbiological processes.However,scattering in biological tissues is a major obstacle that preventshigh-resolution images from being obtained from deep regions of tissue.We review commontechniques,such as multiphoton microscopy(MPM)and optical coherence microscopy(OCM),for diffraction limited imaging beyond an imaging depth of 0.5 mm.Novel implementations havebeen emerging in recent years giving higher imaging speed,deeper penetration,and better imagequality.Focal modulation microscopy(FMM)is a novel method that combines confocal spatialfltering with focal modulation to reject out-of-focus background.FMM has demonstrated animaging depth comparable to those of MPM and OCM,near-real-time image acquisition,and thecapability for multiple contrast mechanisms.

Stimulated Raman scattering microscopy on biological cellular machinery

Beneting from the developments of advanced optical microscopy techniques,the mysteries of biological functions at the cellular and subcellular levels have been continuously revealed.Stimulated Raman scattering(SRS)microscopy is a rapidly growing technique that has attracted broad attentions and become a powerful tool for biology and biomedicine,largely thanks to its chemical specicity,high sensitivity and fast image speed.This review paper introduces the principles of SRS,discusses the technical developments and implementations of SRS microscopy,then highlights and summarizes its applications on biological cellular machinery andnally shares our visions of potential breakthroughs in the future.

Coherent optical adaptive technique improves the spatial resolution of STED microscopy in thick samples

Stimulated emission depletion(STED) microscopy is one of far-field optical microscopy techniques that can provide sub-diffraction spatial resolution. The spatial resolution of the STED microscopy is determined by the specially engineered beam profile of the depletion beam and its power. However, the beam profile of the depletion beam may be distorted due to aberrations of optical systems and inhomogeneity of a specimen's optical properties, resulting in a compromised spatial resolution. The situation gets deteriorated when thick samples are imaged. In the worst case, the severe distortion of the depletion beam profile may cause complete loss of the superresolution effect no matter how much depletion power is applied to specimens. Previously several adaptive optics approaches have been explored to compensate aberrations of systems and specimens. However, it is difficult to correct the complicated high-order optical aberrations of specimens. In this report, we demonstrate that the complicated distorted wavefront from a thick phantom sample can be measured by using the coherent optical adaptive technique. The full correction can effectively maintain and improve spatial resolution in imaging thick samples.

反射式共聚焦显微镜联合光学相干断层成像在黄褐斑微观辨证中的作用

目的探讨不同中医证型女性黄褐斑皮损的微观差异。方法收集2023年1月—2023年12月在华中科技大学同济医学院附属武汉中西医结合医院皮肤科门诊确诊的113例女性黄褐斑患者,在判断其符合纳入标准并征得患者知情同意后,收集整理患者资料并对其进行中医分型,将黄褐斑分为肝郁血瘀型、脾虚型、肾阳虚型及肝肾阴虚型。同时对各型患者行反射式共聚焦显微镜(RCM)、光学相干断层成像(OCT)检查,观察和分析女性黄褐斑各中医证型皮肤组织形态学特征。结果113例女性黄褐斑患者中,中医辨证分型包括肝郁血瘀型51例(45.13%),脾虚型34例(30.09%),肾阳虚型16例(14.16%),肝肾阴虚证12例(10.62%)。入选对象皮损处RCM下表皮色素数量分布均见增加,以patternⅡ、patternⅢ模式占比居多;均有显著的黑素细胞活跃现象,主要以patternⅠ、patternⅡ模式占比居多,四种主要证型间无显著差异。肝肾阴虚型RCM下以混合型改变为主,表皮黑素颗粒分布明显增多,黑素细胞明显活跃,黑素细胞悬垂及真皮层噬黑素细胞浸润均显著;脾虚型RCM下以表皮型改变为主,真皮内噬黑素细胞浸润出现比例较低;OCT观察发现黄褐斑皮损毛细血管网深度,平均分布在皮下54.57±14.19μm之间,四种主要证型间无统计学差异。肝郁血瘀型黄褐斑皮损中,血管扩张改变较其他三型显著。结论不同中医证型黄褐斑皮损,其组织学改变具有一定差异性和规律性,皮肤影像学指标可为中医辨证,个体精准化治疗提供必要的客观参考依据。

皮肤影像技术在鳞状细胞癌诊疗中的研究进展

皮肤鳞状细胞癌是仅次于基底细胞癌的第二常见的皮肤恶性肿瘤。虽然鳞癌的金标准是组织病理学检查,但病理组织取材会给患者造成创伤,因此光学无创诊断技术得到越来越多的关注。本文综述了近年来皮肤镜、高频超声、反射式共聚焦显微镜、皮肤光学相干层析成像技术等皮肤无创影像技术在皮肤鳞状细胞癌诊疗的研究进展。

Evaluation of ablation differences in air and water for hard tissues using full-field optical coherence microscopy

To clarify the role of a natural or artificial liquid environment in the free-running infrared pulsed laser ablation of hard biological tissues,two-and three-dimensional morphologies of laser-induced craters must be quantitatively measured to distinguish ablation differences in air and in water.Full-field optical coherence microscopy is introduced,which has non-contact,non-destructive,non-preprocessing and higher-resolution advantages.Experimental results indicate that the ablation performances in air and in water are comparable for few laser pulses,but the ablation difference becomes obvious for more laser pulses.Optical coherence microscopy is more feasible than conventional means for the morphological measurement of craters.

Latest advances in soft X-ray spectromicroscopy at SSRF

The BL08U1 A beamline is established as a sophisticated platform at Shanghai Synchrotron Radiation Facility(SSRF), taking advantage of its high spatial resolution(< 30 nm) and high energy resolving power(>10 000),for studying properties of solid, liquid, gas, film and other forms of materials at sub-micron scale. In this paper,we present a review on newly implemented techniques, such as total electron yield(TEY), dual energy contrast imaging, nano-CT, soft X-ray excited optical luminance(SXEOL), and coherent diffraction imaging(CDI)under development. Several research cases in nanomaterials, environmental science and biology are presented to demonstrate capabilities of the beamline.

SDOCT IMAGE RECONSTRUCTION BY INTERFEROMETRIC SYNTHETIC APERTURE MICROSCOPY

Spectral domain optical coherence tomography(SDOCT)is a noninvasive,cross-sectional imaging technique that measures depth resolved reflectance of tissue by Fourier transforming the spectral interferogram with the scanning of the reference avoided.Interferometric synthetic aperture microscopy(ISAM)is an optical microscopy computed-imaging technique for measuring the optical properties of biological tissues,which can overcome the compromise between depth of focus and transverse resolution.This paper describes the principle of SDOCT and ISAM,which multiplexes raw acquisitions to provide quantitatively meaningful data with reliable spatially invariant resolution at all depths.A mathematical model for a coherent microscope with a planar scanning geometry and spectral detection was described.The two-dimensional fast Fourier transform(FFT)of spectral data in the transverse directions was calculated.Then the nonuniform ISAM resampling and filtering was implemented to yield the scattering potential within the scalar model.Inverse FFT was used to obtain the ISAM reconstruction.One scatterer,multiple scatterers,and noisy simulations were implemented by use of ISAM to catch spatially invariant resolution.ISAM images were compared to those obtained using standard optical coherence tomography(OCT)methods.The high quality of the results validates the rationality of the founded model and that diffraction limited resolution can be achieved outside the focal plane.

基于傅里叶叠层显微成像术的定量相干传递函数恢复

研究了在不同系统误差和不同目标算法下相干传递函数的重建质量,发现相干传递函数的重建比物体的重建更稳健。基于此,报道了一种用于傅里叶叠层显微成像术的子区域平移方法,以加速有限图像下的相干传递函数重构收敛速度,消除由周期性照明光源阵列引起的栅格噪声,实现图像的重聚焦,并使用相干传递函数去卷积提高图像的对比度。此外,研究了傅里叶叠层显微成像术的空域和频域数据冗余来恢复相干传递函数,发现至少需要大约40%的频谱交叠率来精确重建相干传递函数,比无像差条件下高出10%,为了相干传递函数的稳定性需要至少25张原始低分辨率图像。最后,讨论了稳定的相干传递函数重建所需的条件,并通过模拟和实验进行了验证。

Line-field confocal optical coherence tomography for three-dimensional skin imaging

This paper reports on the latest advances in line-field confocal optical cohere nee tomography(LC-OCT),a recently invented imaging technology that now allows the generation of either horizontal(x×y)section images at an adjustable depth or vertical(x×z)section images at an adjustable lateral position,as well as thre dimensional images.For both two-dimensional imaging modes,images are acquired in real-time,with real-time control of the depth and lateral positions.Three-dimensional(x×y×z)images are acquired from a stack of horizontal section images.The device is in the form of a portable probe.The handle of the probe has a button and a scroll wheel allowing the user to control the imaging modes.Using a supercontinuum laser as a broadband light source and a high numerical microscope objective,an isotropic spatial resolution of^1|im is achieved.The field of view of the three-dimensional images is 1.2 mm×0.5 mm×0.5 mm(x×y×z).Images of skin tissues are presented to demonstrate the potential of the technology in dermatology.

微结构显微光学无损检测方法(特邀)

微纳尺度的微结构可调制光场,提高传感器的灵敏度,是新一代功能器件或传感器件中广泛使用的重要结构特征。包含微细加工在内的先进制造技术的快速发展,对多种型式微纳尺度微结构的无损测量技术提出了紧迫的需求。本文从多维视角论述了国内外行业发展中出现的微结构种类、型式,围绕具有高精度无损检测特质的光学显微技术,阐述了国内外仍在继续发展的微结构无损检测四种主流方法,分析了这些方法的技术特点、适用对象,给出了典型样品的检测结果,其中部分结果是首次发表。结果表明,暗场显微机器视觉法,是振幅型颗粒、凹坑、划痕等有害微结构的有效检测方法,可以实现大尺度样品的快速检测;共焦显微成像和低相干显微干涉法是“相位”型微结构的最佳检测方法,可以得到微结构的三维形貌;光谱反演-过焦扫描法与近红外显微干涉法,是应高深宽比微结构无损检测需求而发展起来的新方法,前者可以快速测得线宽和深度,后者可以测得物镜视场范围内高深宽比微结构的三维形貌,二者可以相互验证与补充。

UBM、SL-OCT及房角镜检查前房角结构的比较

目的探讨超声生物显微镜(ultrasound biomicroscope,UBM)、裂隙灯前节光学相干断层成像(slit lamp optical coherence tomography,SL-OCT)与房角镜检查房角后退和房角关闭的一致性。方法在同一暗室中对被检查眼上方、下方、颞侧、鼻侧4个方位进行UBM、SL-OCT及房角镜检查,记录前房角情况,应用χ2检验和Kappa检验对3种检查方法就房角关闭、房角后退的检查结果一致性进行比较。结果应用UBM、SL-OCT及房角镜检查判断房角关闭和房角后退,3种检查方法差异无统计学意义(P>0.05),UBM与房角镜检查房角后退结果一致性更好(Kappa值0.882),而SL-OCT与房角镜检查房角后退结果一致性一般(Kappa值0.624)。结论以房角镜检查作为标准,对房角后退的判断UBM优于SL-OCT;对房角关闭的判断,UBM、SL-OCT及房角镜检查一致性均良好。

新型光学成像技术及其在生物医学中的应用

本文介绍了在生物医学中有广泛应用前景的共焦扫描光学显微镜、扫描近场光学显微术和光学相干微术三种新型成像技术的基本原理和应用。

PachPen超声角膜测厚仪与两种光学测量仪器在中央角膜厚度测量中的对比

目的:比较不同设备在中央角膜厚度(CCT)测量方面的异同,为临床提供一种安全、有效、简便、准确的角膜厚度测量方法。方法:连续入选2016-09/12于上海中医药大学附属普陀医院眼科行术前检查的白内障患者95例95眼,分别采用手持式自动PachPen超声角膜测厚仪、眼前节光学相干断层扫描仪(AS-OCT)及角膜内皮镜测量中央角膜厚度,并同时测量眼压。观察三种不同设备在中央角膜厚度测量方面的异同及其与眼压的相关性,并行统计学分析。结果:PachPen超声角膜测厚仪测量CCT为544.43±36.61μm,AS-OCT测量CCT为527.09±35.54μm,角膜内皮镜测量CCT为533.20±30.17μm,三组比较差异具有统计学意义(F=6.272,P=0.002),PachPen超声角膜测厚仪测出的CCT较另外两组显著增高。三者与眼压的相关系数分别为0.290、0.277和0.204(P<0.05),其中PachPen超声角膜测厚仪测出的CCT与眼压之间的相关性最高。三种测量方法测得的CCT之间均显著相关(P<0.001)。结论:PachPen超声角膜测厚仪测量出的中央角膜厚度最厚,其次是角膜内皮镜,AS-OCT测量值最小,三种设备测量中央角膜厚度有明显相关性和较好的一致性,与眼压均具有相关性。