In vivo imaging of human oral hard and soft tissues by polarization-sensitive optical coherence tomography

Walther, Julia; Golde, Jonas; Kirsten, Lars; Tetschke, Florian; Hempel, Franz; Rosenauer, Tobias; Hannig, Christian; Koch, Edmund

doi:10.1117/1.jbo.22.12.121717

Cited by 18 publications

(7 citation statements)

References 54 publications

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“…Presence of false positives speaks to the non-specific nature of light scattering contrast mechanism which is enhanced as a result of discontinuities in refractive index, not necessarily caused by demineralization. While non-specific nature of OCT images of early caries has also been reported by other investigators [ 14 , 36 ], recent studies suggest that this problem can be alleviated using PS-OCT [ 21 ]. TPLI images, on the other hand, display enhancement of contrast only within the treated area because laser excitation is selectively absorbed in these regions; thus, yielding minimal false positive readings.…”

Section: Resultsmentioning

confidence: 80%

Comparative study on the detection of early dental caries using thermo-photonic lock-in imaging and optical coherence tomography

Shokouhi¹,

Razani²,

Gupta³

et al. 2018

Biomed. Opt. Express

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Early detection of dental caries is known to be the key to the effectiveness of therapeutic and preventive approaches in dentistry. However, existing clinical detection techniques, such as radiographs, are not sufficiently sensitive to detect and monitor the progression of caries at early stages. As such, in recent years, several optics-based imaging modalities have been proposed for the early detection of caries. The majority of these techniques rely on the enhancement of light scattering in early carious lesions, while a few of them are based on the enhancement of light absorption at early caries sites. In this paper, we report on a systemic comparative study on the detection performances of optical coherence tomography (OCT) and thermophotonic lock-in imaging (TPLI) as representative early caries detection modalities based on light scattering and absorption, respectively. Through controlled demineralization studies on extracted human teeth and µCT validation experiments, several detection performance parameters of the two modalities such as detection threshold, sensitivity and specificity have been qualitatively analyzed and discussed. Our experiment results suggests that both modalities have sufficient sensitivity for the detection of well-developed early caries on occlusal and smooth surfaces; however, TPLI provides better sensitivity and detection threshold for detecting very early stages of caries formation, which is deemed to be critical for the effectiveness of therapeutic and preventive approaches in dentistry. Moreover, due to the more specific nature of the light absorption contrast mechanism over light scattering, TPLI exhibits better detection specificity, which results in less false positive readings and thus allows for the proper differentiation of early caries regions from the surrounding intact areas. The major shortcoming of TPLI is its inherent depth-integrated nature, prohibiting the production of depth-resolved/B-mode like images. The outcomes of this research justify the need for a light-absorption based imaging modality with the ability to produce tomographic and depth-resolved images, combining the key advantages of OCT and TPLI.

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Section: Resultsmentioning

confidence: 80%

Comparative study on the detection of early dental caries using thermo-photonic lock-in imaging and optical coherence tomography

Shokouhi¹,

Razani²,

Gupta³

et al. 2018

Biomed. Opt. Express

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“…13 In contrast to the majority of previous studies, where average birefringence is computed from the cumulative retardance from the tissue surface to a given depth, here, we provide local birefringence at close to the same resolution as the OCT intensity images. Separately, in our recent in vivo study, 17 . The measured image data were first flattened by automatic subtraction of the extracted position of the tissue surface, so each en face slice corresponds to a given depth below the tissue surface (as marked by the red dotted curve on the cross-sections in Figs.…”

Section: Polarization-sensitive Octmentioning

confidence: 92%

“…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.…”

Section: Introductionmentioning

confidence: 99%

Influence of tissue fixation on depth-resolved birefringence of oral cavity tissue samples

Karnowski

Poudyal

et al. 2020

J. Biomed. Opt.

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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.

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“…Since their invention in the 1960s, lasers have served diverse technologies, many of which benefit from polarization control, beam shaping, and polarization smoothing that underlie laser-based devices for optical communications, − laser power scaling, and biological and medical imaging, , to name a few. With the ease of device scale-up at affordable costs, liquid crystal devices have become essential for polarization control, including circular and linear polarizers, and waveplates, using, in particular, cholesteric and nematic classes that are readily processed into large-area defect-free films.…”

Section: Introductionmentioning

confidence: 99%

Mesomorphic Ceramic Films Synthesized via Lyotropic Self-Assembly of Metal Oxide Nanorods Complete with Sintering

Zhang

Chen

Hilfiker

et al. 2020

ACS Appl. Nano Mater.

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Mesomorphic ceramics are broadly defined as solid systems with morphologies intermediate between isotropic materials and single crystals. To illustrate this materials concept, a class of mesomorphic ceramics with nematic-like superstructures has been synthesized via lyotropic liquid crystals of titanium dioxide, TiO2, in an isotropic solvent for a demonstration of uniaxially oriented solid films. A lyotropic dispersion of ligand-capped anatase nanorods at 60 wt % in chlorobenzene was calcined and sintered with prior manual shear to form an optically anisotropic, 2.3 ± 0.3 μm-thick solid film. In the course of sintering, nanorods fuse into low-aspect ratio grains that form nematic domains. Shear-induced alignment of nanorods followed by thermal treatment creates uniaxial orientation across millimeters, which exhibits high optical transparency and a nearly constant birefringence of 0.018 ± 0.002 from 650 to 1700 nm. Distinct from liquid-crystal templating, this new approach yields superstructures of nanoparticles with relative ease and at lower costs. The present study opens a pathway toward robust, ceramic-based solid films for diverse application.

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In vivo imaging of human oral hard and soft tissues by polarization-sensitive optical coherence tomography

Cited by 18 publications

References 54 publications

Comparative study on the detection of early dental caries using thermo-photonic lock-in imaging and optical coherence tomography

Comparative study on the detection of early dental caries using thermo-photonic lock-in imaging and optical coherence tomography

Influence of tissue fixation on depth-resolved birefringence of oral cavity tissue samples

Mesomorphic Ceramic Films Synthesized via Lyotropic Self-Assembly of Metal Oxide Nanorods Complete with Sintering

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