Fig 1 - uploaded by V. A. Kamensky
Content may be subject to copyright.
Standard OCT images printed in logarithmic scale of different diseases a) laryngitis (chronic inflammation of larynx) b) laryngeal cancer c) laryngeal papilloma. White bar corresponds to 1 mm.
Source publication
An experimental standard optical coherence tomography (OCT) setup that can be easily modified for cross-polarization OCT (CP OCT) operation has been developed to perform differential diagnosis of pathological tissues. The complementary use of CP OCT, a technique that provides a map of cross-polarization backscattering properties of an object being...
Context in source publication
Context 1
... OCT images of cancer are structureless and, as a rule, show fast signal decay with depth. OCT is informative with regard to structural alterations in tissue, although it does not specify the origin of these alterations. Using OCT imaging, it is very difficult to differentiate inflammatory processes, papillomatosis, cancer, and scar changes (Fig. ...
Citations
... The depolarized signal originates from effective backscatter by nonspherical objects or large clustered particles [15]. Conversely, parallel or co-polarized OCT signals highlight reflection from robust reflectors, overshadowing scattering signals [16]. A comparative analysis of these signals promises insights into the anatomical basis of hyper-and hypo-reflective OCT bands. ...
... This depolarized signal, recorded in crosspolarization OCT, originates from multiply scattered photons from diffuser-like cellular structures like mitochondria in the EZ layer and RPE [26]. In contrast, parallel or copolarization OCT signals accentuate reflections from layer-like reflectors, overshadowing scattering signals [27]. A comparative analysis of these distinct signals holds the potential to yield valuable insights into the anatomical foundations of hyper-and hypo-reflective OCT bands. ...
Precise interpretation of the anatomical origins of outer retinal optical coherence tomography (OCT) presents technical challenges owing to the delicate nature of the retina. To address this challenge, our study introduces a novel polarization-sensitive full-field OCT (FF-OCT) that provides parallel-polarization and cross-polarization OCT measurements, predominantly capturing ballistically reflected photons and multiply scattered photons, respectively. Notably, parallel-polarization OCT unveils layer-like structures more effectively, including the inner plexiform layer (IPL) sub-layers, outer plexiform layer (OPL) sub-layers, and rod/cone OS tips, compared to cross-polarization OCT. Through a comparative analysis of parallel-polarization and cross-polarization OCT images of the outer retina, we discovered that the 2nd outer retinal OCT band results from contributions from both the ellipsoid zone (EZ) and the inner segment/outer segment (IS/OS) junction. Similarly, the 3rd outer retinal OCT band appears to reflect contributions from both the interdigitation zone (IZ) and photoreceptor OS tips. This polarization-sensitive approach advances our understanding of the origins of outer retinal OCT signals and proposes potential new biomarkers for assessing retinal health and diseases
... In order to assess this in vivo, we first utilized cross-polarized optical 213 coherence tomography (CP-OCT). CP-OCT reports on relative changes in the polarization 214 of incident light and can provide additional contrast to the native tissue based on its 215 structural differences, including ECM structure (36,37). Consistent with the changes in 216 . ...
Extracellular matrix (ECM) deposition after central nervous system (CNS) injury leads to inhibitory scarring in mammals, whereas it facilitates axon regeneration in the zebrafish. However, the molecular basis of these different fates is not understood. Here, we identify small leucine-rich proteoglycans (SLRPs) as a causal factor in regeneration failure. We demonstrate that the SLRPs Chondroadherin, Fibromodulin, Lumican, and Prolargin are enriched in human, but not zebrafish, CNS lesions. Targeting SLRPs to the zebrafish injury ECM inhibits axon regeneration and functional recovery. Mechanistically, we find that SLRPs confer structural and mechanical properties to the lesion environment that are adverse to axon growth. Our study reveals SLRPs as previously unknown inhibitory ECM factors in the human CNS that impair axon regeneration by modifying tissue mechanics and structure.
ONE SENTENCE SUMMARY
Composition, structural organization, and mechanical properties of the injury ECM direct central nervous system regeneration.
... Along this line, OCT systems that can detect the change in the polarization of the light as it interacts with the tissue have been proposed. There are two variants of the OCT systems, namely polarization-sensitive optical coherence tomography (PS-OCT) systems [19][20][21] and cross-polarized optical coherence tomography (CP-OCT) systems [22][23][24][25][26][27][28] which have been demonstrated. CP-OCT systems are simpler than PS-OCT systems because such systems do not require defined polarization of light to study the tissue. ...
... CP-OCT systems are simpler than PS-OCT systems because such systems do not require defined polarization of light to study the tissue. CP-OCT systems have been used in the past to image collagen within the esophagus [26], oral mucosa [29], and bladder [30]. Since dense connective tissue within the tonsil is made up of collage [16], the CP-OCT technique offers a great advantage in terms of its simplicity and enhanced contrast. ...
The palatine tonsils provide the first line of immune defense against foreign pathogens inhaled or ingested. However, a disruption in the epithelial layer within the tonsil crypts can lead to recurrent acute tonsillitis (RAT). Current imaging techniques suffer from poor resolution and contrast and do not allow a classification of the severity of RAT. We have developed a cross-polarized optical coherence tomography system. The system can detect a change in the polarization of the light after the light-tissue interaction. We demonstrate improved resolution and contrast in tonsil imaging with the developed method. Intensity, as well as retardance images of the excised tonsil tissue, were acquired. Features such as crypt epithelium, lymphoid follicles, and dense connective tissue were observed with improved contrast. Cross polarized optical coherence tomography can be a valuable tool in the clinic to evaluate palatine tonsils as it would allow visualizing common tonsil features without the need for any external contrast agent.
... To do so, the change in the polarization of the input light from the sample is measured using a reference light signal which has some known relation to the light used for illumination of the sample. Both PS-OCT [9][10][11][12] and CP-OCT [13][14][15][16] systems have been developed for this purpose. PS-OCT has been used to reconstruct entire Jones matrices for the tissue, which allows measuring the birefringence as well as the optic axis orientation of the sample. ...
... In many cases, however, it is sufficient to know the overall change in polarization without the need for the full Jones matrix of the tissue. CP-OCT systems offer an advantage over PS-OCT systems, due to being simpler in their implementation, and have been used for esophageal cancer detection [14], brain tumor imaging [13], bladder cancer detection [15], endomyocardial imaging [17], and dental biofilm imaging [16]. ...
Cross-polarized optical coherence tomography offers improved contrast for samples which can alter the polarization of light when it interacts with the sample. This property has been utilized to screen pathological conditions in several organs. Existing cross-polarized optical coherence tomography systems require several polarization-controlling elements to minimize the optical fiber movement-related image artifacts. In this work, we demonstrate a cross-polarized optical coherence tomography system using unpolarized light and only two quarter-wave plates, which is free from fiber-induced image artifacts. The simplicity of the approach will find many applications in clinical settings.
... Here we briefly summarise common phantoms used for biomedical polarimetric techniques. These techniques include polarised wide-field microscopy 16,24,183 , polarised light spatial frequency imaging 184 , polarimetric endoscopy [185][186][187][188][189][190] , spectral light scattering polarimetry 18,82,[191][192][193] , polarised fluorescence spectroscopy [194][195][196] , polarised confocal microscopy 197 , polarised Raman-spectroscopy 198,199 , polarised super-resolution microscopy 154,155 , polarisation sensitive optical coherence tomography [200][201][202][203][204][205][206][207][208][209][210][211][212][213][214][215][216][217][218] , non-diffraction beam polarimetry (such as Bessel beam based) 219 , polarisationresolved nonlinear microscopy (including second/third harmonic generation) [220][221][222][223][224][225][226] , and polarised speckle imaging 213,227 (several techniques will be mentioned again in the Discussion). The relationship between incoherence and depolarisation of the light should be kept in mind when considering coherence based polarimetric techniques: they are different but related optical concepts. ...
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.
... CP-OCT is a variation of the standard OCT that enhances the detection of the underlying defects in birefringence biological tissues and nonmetallic substrates by detecting the backscattered signals that are at right-angle to linearly polarized probing signals. [20] The aim of this study was to optically quantify the interfacial microleakage in primary teeth bonded to two different adhesives and composite restorations. The null hypothesis was that there is no difference between the groups regardless of the adhesive-composite combination. ...
Background:
Although the demand for esthetic filling of primary teeth with resin composite is increasing, there is no enough data on the adhesive performance of composite restorations in primary teeth. Despite the improvements in resin composites, interfacial gap is still a disadvantage as it may cause marginal staining, secondary caries, and restoration failure. Previous studies have validated the efficiency of optical coherence tomography (OCT) in the evaluation of adhesive interface in permanent teeth, but not in primary teeth.
Aims:
The aim of this study was to assess microleakage upon composite restorations in primary teeth using cross-polarization OCT (CP-OCT).
Methodology:
Cylindrical class-V cavities were prepared in extracted human primary second molars and divided into four groups randomly. In groups 1 and 2, cavities were restored using Tetric N-Universal adhesive in the self-etch mode followed by IPS Impress Direct Composite and Ceram.x One Universal composite, respectively. In groups 3 and 4, one-step self-etch Prime and Bond Elect adhesive was used followed by ID composite and CX composite in groups 3 and 4, respectively. The specimens were then immersed in a contrasting solution followed by interfacial microleakage examination under CP-OCT. The recorded images were analyzed to quantify the mean gap percentages.
Results:
All tested groups showed variable degree of interfacial microleakage under composite restorations. Two-way ANOVA showed the composite factor was significantly influencing the results, unlike the adhesive. Group 1 and 2 had the lowest and highest mean gap percentage, respectively, which were significantly different from the other groups. Groups 3 and 4 were not significantly different.
Conclusion:
Based on the current finding, a polymeric restorative system from the same manufacturer reduces the risk of interfacial microleakage in primary teeth.
... CpOCT requires two images of the same sample area. Therefore, the polarisation of the illumination used to acquire the first image has to be strictly orthogonal to the second one [36]. Alternatively both images can be taken simultaneously [17], like in our case, applying light which contains both polarisation states at once. ...
Within the last decades, several studies have been published that prove the benefit of polarisation sensitive optical coherence (psOCT) tomography for the field of biomedical diagnostics. However, polarisation sensitive imaging typically requires careful control of the polarisation state of the input illumination, which leads to bulky and delicate systems. While psOCT provides quantitative information, it is mostly sufficient to analyse the images qualitatively in the field of biomedical diagnostics. Therefore, a reduced form of this technique, cross-polarised optical coherence tomography (cpOCT), moves into the focus of interest that serves to visualise the birefringence properties of a sample. Despite the low requirements for the illumination’s polarisation, most of the proposed systems still include complex illumination control mechanisms. Here, we propose a common path probe based endoscopic system with an lateral resolution of 30 µm and a sensitivity of 103 dB comprising a commercially available swept-source OCT system and a free-space module which does not require any polarisation controlling elements. A Faraday mirror substitutes the complex polarisation control apparatus. We demonstrate the independence of the approach from the polarisation state of the light source by monitoring the illumination power in the orthogonal channels while varying the source polarisation. Furthermore, we validate the ability of the system to reveal the birefringence properties of different samples, starting from a quarter-wave plate, since its properties are fully characterised. Additionally, we present imaging results from several tissues to demonstrate its feasibility for the field of biomedical diagnostics.
... The interferometric selection of the depth, from which the signal is backscattered, and measurement of the variation in its polarization with respect to the incident-wave polarization allow one to determine such properties as depolarization, birefringence, dichroism, and orientation of polarization axes [15,16]. Such polarization characteristics provide information on the presence of certain ordered structures (e.g., concentration and type of collagen fibers, their local orientation in the near-surface layers [15,17]), as well as on the tissue microstructural features [15]. The evolution of polarization as a function of the scattering depths is usually characterized using the formalism of Jones and Mueller matrices [11][12][13][18][19][20][21]. ...
... The radiation with polarization coinciding with that of the initial signal is received in the so-called co-channel, whereas the signal with the orthogonal polarization is recorded in the cross-channel of the OCT scanner. In the cross-channel the backscattered radiation can appear due to the influence of both regular birefringence and scattering from individual heterogeneities in the tissue [6,8,17,[22][23][24]. The degree of backscattering in the orthogonal polarization depends on the size, structure, and anisotropy properties of the optical heterogeneities in the medium [8] and can characterize, for example, the state of collagen tissues, which is especially important for diagnostics of cancer pathologies [17,25]. ...
... In the cross-channel the backscattered radiation can appear due to the influence of both regular birefringence and scattering from individual heterogeneities in the tissue [6,8,17,[22][23][24]. The degree of backscattering in the orthogonal polarization depends on the size, structure, and anisotropy properties of the optical heterogeneities in the medium [8] and can characterize, for example, the state of collagen tissues, which is especially important for diagnostics of cancer pathologies [17,25]. As experiments indicate [8], the effectiveness of cross-polarization scattering is especially high for relatively large-scale heterogeneities and is much weaker manifested for heterogeneities with sizes smaller than the optical wave length. ...
... Polarization-sensitive OCT (PS-OCT) has demonstrated polarization contrast between uninvolved stroma and tumor 13,14 and, by contrast, does not require tissue compression. Various studies using PS-OCT on healthy and pathologically altered animal 15 and human [16][17][18][19][20] oral tissue samples have revealed promising enhanced contrast provided by differences in the polarization properties of oral cavity tissue structures. An important recent advance is the refinement of reconstruction methods to enable extraction of local tissue birefringence (localized in depth), which has led to marked improvements in contrast and fidelity with tissue morphology, including in (healthy) oral cavity tissues. ...
Significance:
To advance our understanding of the contrast observed when imaging with polarization-sensitive optical coherence tomography (PS-OCT) and its correlation with oral cancerous pathologies, a detailed comparison with histology provided via ex vivo fixed tissue is required. The effects of tissue fixation, however, on such polarization-based contrast have not yet been investigated.
Aim:
A study was performed to assess the impact of tissue fixation on depth-resolved (i.e., local) birefringence measured with PS-OCT.
Approach:
A PS-OCT system based on depth-encoded polarization multiplexing and polarization-diverse detection was used to measure the Jones matrix of a sample. A wide variety of ex vivo samples were measured freshly after excision and 24 h after fixation, consistent with standard pathology. Some samples were also measured 48 h after fixation.
Results:
The tissue fixation does not diminish the birefringence contrast. Statistically significant changes were observed in 11 out of 12 samples; these changes represented an increase in contrast, overall, by 11% on average.
Conclusions:
We conclude that the fixed samples are suitable for studies seeking a deeper understanding of birefringence contrast in oral tissue pathology. The enhancement of contrast removes the need to image immediately postexcision and will facilitate future investigations with PS-OCT and other advanced polarization-sensitive microscopy methods, such as mapping of the local optic axis with PS-OCT and PS-optical coherence microscopy.
