CHARACTERISTIC FEATURES OF MUELLER MATRIX PATTERNS FOR POLARIZATION SCATTERING MODEL OF BIOLOGICAL TISSUES

We developed a model to describe polarized photon scattering in biological tissues.In this model,tissues are simplified to a mixture of scatterers and surrounding mpdium.There are t wo types ofscatterers in the model:solid spheres and infinitely long solid cylinders.Variables related to thescatterers include:the densities and sizes of the spheres and cylinders,the orientation and angulardistribution of cylinders.Variables related to the surrounding medium include:the refractiveindex,absorption coeficient and birefringence.In this paper,as a development we introduce anoptical activity effct to the model.By comparing experiments and Monte Carlo simulations,we analyze the backscater ing Mueller matrix patterms of several tissue-like media,and summarizethe different effects coming from anisotropic scattering and optical properties.In addition,wepropose a possible method to extract the optical activity values for tissues.Both the experimentaland simulated results show that,by analyzing the Mueller matrix patterns,the microstructureand optical properties of the medium can be obtained.The characteristic features of Muellermatrix patterns are potentilly powerful tools for studying the contrast mechanisms of polari-zation imaging for medical diagnosis.

QUANTITATIVE MUELLER MATRIX POLARIMETRY TECHNIQUES FOR BIOLOGICAL TISSUES

We propose and conduct both the rotating linear polarization imaging(RLPI)and Mueller matrix transformation(MMT)measurements of different biological tissue samples,and testify the capability of the Mueller matrix polarimetry for the anisotropic scattering media.The independent parameters extracted from the RLPI and MMT techniques are compared and analyzed.The tissue experimental results show that the parameters are closely related to the structural characteristics of the turbid scattering media,including the sizes of the scatterers,the angular distribution and order of alignment of thefibers.The results and conclusions in this paper may provide a potential method for the detection of precancerous and early stage cancerous tissues.Also,such studies represent the Mueller matrix transformation procedure which results in a set of parameters linking up the Mueller matrix elements to the structural and optical properties of the media.

Microenvironment-responsive metal-phenolic network release platform with ROS scavenging,anti-pyroptosis,and ECM regeneration for intervertebral disc degeneration

Intervertebral disc degeneration(IVDD)can be caused by aging,injury,and genetic factors.The pathological changes associated with IVDD include the excessive accumulation of reactive oxygen species(ROS),cellular pyroptosis,and extracellular matrix(ECM)degradation.There are currently no approved specific molecular therapies for IVDD.In this study,we developed a multifunctional and microenvironment-responsive metal-phenolic network release platform,termed TMP@Alg-PBA/PVA,which could treat(IL-1β)-induced IVDD.The metal-phenolic network(TA-Mn-PVP,TMP)released from this platform targeted mitochondria to efficiently scavenge ROS and reduce ECM degradation.Pyroptosis was suppressed through the inhibition of the IL-17/ERK signaling pathway.These findings demonstrate the versatility of the platform.And in a rat model of IVDD,TMP@Alg-PBA/PVA exhibited excellent therapeutic effects by reducing the progression of the disease.TMP@Alg-PBA/PVA,therefore,presents clinical potential for the treatment of IVDD.

Influence of absorption in linear polarization imaging of melanoma tissues

The contrast mechanism of different polarization imaging techniques for melanoma in mouse skin is st udied using both experiments and Monte Carlo simulations.Total intensity,linear polariz-ation diference imaging(DPI),degree of polarization imaging(DOPI)and'rotating linearpolarization imaging(RLPl)are applied and the relative contrasts of these polarization imagingmethods between the normal and cancerous tissues are compared.A two-layer absorption-scat-tering model is proposed to explain the contrast mechanism of the polarization imaging formelanoma.By taking into account of both scattering of symmetrical and asymmetrical scat terersand absorption of inter-scatterer medium,the two-layer model reproduces the relative con trastsfor polarization images observed in experiments.The simulation results also show that,theparameters of polarization imaging change more dramatically with the variation of absorption inthe bottom layer than the top layer.

POLARIZATION IMAGING AND SCATTERING MODEL OF CANCEROUS LIVER TISSUES

We apply diferent polarization imaging techniques for cancerous liver tissues,and compare the relative contrasts for difference polarization imaging(DPI),degree of polarization imaging(DOPI)and rotating linear polarization imaging(RLPI).Experimental results show that a number of polarization imaging parameters are capable of differentiating cancerous cells in isotropic liver tisues.To analyze the contrast mechanism of the cancer:-sensitive polarization imaging parameters,we propose a scattering model cont aining two types of spherical scatterers and carry on Monte Carlo simula tions based on this bi-component model.Both the experimental and Monte Carlo simulated results show that the RLPI technique can provide a good imaging contrast of cancerous tissues.The bi-component scattering model provides a useful tool to ana-lyze the contrast mechanism of polarization imaging of cancerous tissues.

Mueller matrix polarimetry for quantitative evaluation of the Achilles tendon injury recovery

Achilles tendon injuries,as a widely existing disease,have attracted a lot of research interest.Mueller matrix polarimetry,as a novel label-free quantitative imaging method,has been widely used in various applications of lesion identification and pathological diagnosis.However,focusing on the recovery process of Achilles tendon injuries,current optical imaging methods have not yet achieved the label-free precise identification and quantitative evaluation.In this study,using Mueller matrix polarimetry,various Achilles tendon injury samples were characterized specifically,and the efficacy of different recovery schemes was evaluated accordingly.Experiments indicate that injured Achilles tendons show less phase retardance,larger diattenuation,and relatively disordered orientation.The combination of experiments with Monte Carlo simulation results illustrate the microscopic mechanism of the Achilles tendon recovery process from three aspects,that is,the increased fiber diameter,a more consistent fiber orientation,and greater birefringence induced by more collagen protein.Finally,based on the statistical distribution of polarization measurements,a polarization specific characterization parameter was extracted to construct a label-free image,which cannot only intuitively show the injury and recovery of Achilles tendon samples,but also give a quantitative evaluation of the treatment.

Revealing complex optical phenomena through vectorial metrics

Advances in vectorial polarization-resolved imaging are bringing new capabilities to applications ranging from fundamental physics through to clinical diagnosis.Imaging polarimetry requires determination of the Mueller matrix(MM)at every point,providing a complete description of an object’s vectorial properties.Despite forming a comprehensive representation,the MM does not usually provide easily interpretable information about the object’s internal structure.Certain simpler vectorial metrics are derived from subsets of the MM elements.These metrics permit extraction of signatures that provide direct indicators of hidden optical properties of complex systems,while featuring an intriguing asymmetry about what information can or cannot be inferred via these metrics.We harness such characteristics to reveal the spin Hall effect of light,infer microscopic structure within laser-written photonic waveguides,and conduct rapid pathological diagnosis through analysis of healthy and cancerous tissue.This provides new insight for the broader usage of such asymmetric inferred vectorial information.

Stereoscopic spatial graphical method of Mueller matrix:Global‑Polarization Stokes Ellipsoid

A Mueller matrix covers all the polarization information of the measured sample,however the combination of its 16 elements is sometimes not intuitive enough to describe and identify the key characteristics of polarization changes.Within the Poincarésphere system,this study achieves a spatial representation of the Mueller matrix:the Global-Polarization Stokes Ellipsoid(GPSE).With the help of Monte Carlo simulations combined with anisotropic tissue models,three basic characteristic parameters of GPSE are proposed and explained,where the V parameter represents polarization maintenance ability,and the E and D†parameters represent the degree of anisotropy.Furthermore,based on GPSE system,a dynamic analysis of skeletal muscle dehydration process demonstrates the monitoring efect of GPSE from an application perspective,while confrming its robustness and accuracy.

Polarisation optics for biomedical and clinical applications:a review

Many polarisation techniques have been harnessed for decades in biological and clinical research,each based upon measurement of the vectorial properties of light or the vectorial transformations imposed on light by objects.Various advanced vector measurement/sensing techniques,physical interpretation methods,and approaches to analyse biomedically relevant information have been developed and harnessed.In this review,we focus mainly on summarising methodologies and applications related to tissue polarimetry,with an emphasis on the adoption of the Stokes-Mueller formalism.Several recent breakthroughs,development trends,and potential multimodal uses in conjunction with other techniques are also presented.The primary goal of the review is to give the reader a general overview in the use of vectorial information that can be obtained by polarisation optics for applications in biomedical and clinical research.

早产儿视网膜病变激光光凝术后角膜地形图状况

目的:观察早产儿视网膜病变(ROP)激光光凝术后儿童角膜地形图的改变。方法:病例对照研究。收集2015年9月至2018年4月于深圳市眼科医院行激光光凝术后的ROP儿童25例(50眼)为ROP组,同时收集年龄匹配的足月儿童23例(46眼)为对照组。2组儿童均行最佳矫正视力(BCVA)检查,统计分析时转换为LogMAR视力。Sirius眼前节分析系统测量2组儿童的各种角膜参数:角膜前后表面不同直径角膜曲率的最大值(K1)和最小值(K2)、平均角膜曲率(Avg);角膜前后表面不同直径的陡峭半径(rs)、平坦半径(rf)、非球面参数(e)。数据采用独立样本t检验进行分析。结果:ROP组儿童BCVA(LogMAR)(0.24±0.25)较对照组儿童(0.07±0.10)差,2组间差异有统计学意义(t=3.20,P=0.003)。ROP组儿童角膜前后表面不同直径范围的角膜屈光力均比对照组儿童大,差异有统计学意义[K1(角膜前表面3、5、7 mm,角膜后表面3、5、7 mm):t=3.139、3.050、2.710,-4.216、-3.821、-2.474;K2:t=2.816、2.688、2.286,-4.252、-3.883、-3.178;Avg:t=3.190、3.041、2.649,-4.848、-4.271、-3.121。均P<0.05]。ROP组儿童角膜前后表面不同直径范围的角膜形态与对照组儿童比较差异均有统计学意义[rf(角膜前表面6、8 mm,角膜后表面6、8 mm):t=3.395、3.354,-4.427、-4.613;rs:t=2.928、2.807,-4.055、-4.175;e:t=3.437、3.991,2.268、4.355,均P<0.05]。结论:Sirius眼前节分析系统是研究ROP激光光凝术后全角膜发育方面的有利工具。ROP激光光凝术后早产儿儿童与足月产儿童相比,角膜前后表面不同范围的屈光力更大,BCVA更差,在视觉发育过程中更易发生屈光不正等视功能改变。