Diffuse light suppression of back-directional gating imaging in high anisotropic media

Xu, Zhengbin; Liu, Jingjing; Kim, Young L.

doi:10.1117/1.3156801

Cited by 10 publications

(10 citation statements)

References 9 publications

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“…Back-directional gating in an imaging setup can significantly suppress diffuse light in biological tissue, including bone tissue, and thus allows the isolation of partial waves in relatively localized volumes, because biological tissue is highly anisotropic. 13 Using our imaging system, we can obtain scattered intensity as a function of x, y, and λ in the area of ∼15×15 mm. 12 We first generated white-light images of our cortical bone specimen by summing all the intensities at the different wavelengths from 400 to 900 nm.…”

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confidence: 99%

Spectroscopic visualization of nanoscale deformation in bone: interaction of light with partially disordered nanostructure

Sun

Liu

et al. 2010

J. Biomed. Opt.

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Abstract. Given that bone is an intriguing nanostructured dielectric as a partially disordered complex structure, we apply an elastic light scattering-based approach to image prefailure deformation and damage of bovine cortical bone under mechanical testing. We demonstrate that our imaging method can capture nanoscale deformation in a relatively large area. The unique structure, the high anisotropic property of bone, and the system configuration further allow us to use the transfer matrix method to study possible spectroscopic manifestations of prefailure deformation.Our sensitive yet simple imaging method could potentially be used to detect nanoscale structural and mechanical alterations of hard tissue and biomaterials in a fairly large field of view. C 2010 Society of Photo-Optical Instrumentation Engineers.[ DOI: 10.1117/1.3514633] Keywords: nanoscale deformation; cortical bone; spectroscopic imaging; transfer matrix method.Paper 10467LR received Aug. 24, 2010; revised manuscript received Oct. 12, 2010; accepted for publication Oct. 18, 2010; published online Dec. 7, 2010. The interaction of light with complex nanostructures has received considerable attention. Because the length scale of the refractive index variations in bone are comparable to the wavelength of light, 1 bone can be considered as a biological nanostructured dielectric in an intermediate regime between ordered photonic structures (e.g., photonic crystals) and completely disordered nanostructures. Bone is a nanocomposite of a mineral phase (e.g., carbonated apatite crystals) and organic matrix (e.g., mainly collagen protein), and the entire structure of bone is highly hierarchical, containing multiscale features from the nanoscales to the macroscales.2, 3 This nanocomposite provides the structural basis for the mineralized collagen fibrils of ∼100 nm in diameter as the basic building block of bone. Microdamage in bone such as microcrack formation and propagation has been intensively studied for better understanding how bone deforms and fractures in terms of plasticity, toughness, and durability. 3,4 There is emerging evidence that such material characteristics are highly attributable to specific nanoscale structures.3, 5 For example, the unique bone structure may allow nanoscale deformation to spread out over a large spatial area as a highly effective energy dissipation mechanism. 5 Daily habitual strain and loading in bone can also be associated with prefailure damage before microcrack formation. 6 Stress distribution of undamaged regions of bone in double-notch specimens has been successfully mapped by converting Raman spectral shifts into stress values.7 Overall, the exact spatial extent of nanoscale prefailure damage in bone still remains relatively unexplored, in part, due to current technical limitations for nondestructively studying its structural properties at nanoscales. 8 Although conventional nanoscale imaging methods such as electron microscopy and atomic force microscopy are highly valuable for investigating various aspects...

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confidence: 99%

Spectroscopic visualization of nanoscale deformation in bone: interaction of light with partially disordered nanostructure

Sun

Liu

et al. 2010

J. Biomed. Opt.

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“…For celecoxib studies (20), a chemopreventive dose of 0.5 mg of celecoxib (LC Laboratories, Woburn, MA, USA) in 0.2 ml acetone (or vehicle alone) was applied topically immediately after each UVB irradiation and 3 times per week after discontinuation of the UVB irradiations. We imaged the irradiated mouse skin every 2 weeks, using our microvascular imaging platform (22, 23) (Supplemental Methods and Figs S1 – S3 for detailed performance characteristics). To obtain sequential images from identical areas over time, we had reference tattoos placed on each mouse to form a rectangular imaging grid.…”

Section: Methodsmentioning

confidence: 99%

Spatiotemporal Assessments of Dermal Hyperemia Enable Accurate Prediction of Experimental Cutaneous Carcinogenesis as well as Chemopreventive Activity

Konger

Sahu

et al. 2013

Cancer Research

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Field cancerization refers to areas of grossly normal epithelium that exhibit increased risk for tumor occurrence. Unfortunately, elucidation of the locoregional changes that contribute to increased tumor risk is difficult due to the inability to visualize the field. In this study, we use a non-invasive optical-based imaging approach to detail spatiotemporal changes in subclinical hyperemia that occur during experimental cutaneous carcinogenesis. After acute inflammation from 10 weeks of ultraviolet B (UVB) irradiation subsides, small areas of focal hyperemia form and were seen to persist and expand long after cessation of UVB irradiation. We show that these persistent early hyperemic foci reliably predict sites of angiogenesis and overlying tumor formation. Over 96% of tumors (57 of 59) that developed following UVB or DMBA/PMA treatment developed in sites of preexisting hyperemic foci. Hyperemic foci were multifocal and heterogeneously distributed and represented a minor fraction of the carcinogen-treated skin surface (10.3% of the imaging area in vehicle treated animals). Finally, we also assessed the ability of the anti-inflammatory agent celecoxib to suppress hyperemia formation during photocarcinogenesis. The chemopreventive activity of celecoxib was shown to correlate with its ability to reduce the area of skin that exhibit these hyperemic foci, reducing the area of imaged skin containing hyperemic foci by 49.1%. Thus, we propose that a hyperemic switch can be exploited to visualize the cancerization field very early in the course of cutaneous carcinogenesis and provides insight into the chemopreventive activity of the anti-inflammatory agent celecoxib.

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“…Elastic Light Scattering-Based Spectroscopic Imaging Setup. Figure 1 illustrates our spectroscopic imaging system described elsewhere [13,16,17]. In brief, a beam from the xenon arc lamp was collimated using a four focal length (4-f) system and delivered onto the specimen through the beamsplitter.…”

Section: Methodsmentioning

confidence: 99%

“…A CCD camera mounted on the spectrograph captured the separated light and recorded a matrix of intensity as a function of pixel locations x, y, and wavelength k (¼400 nm-700 nm). In the imaging platform, cross-talk between adjacent pixels can be minimized to enhance the image contrast and resolution, because back-directional gating can significantly suppress diffuse light in biological tissue [17]. In this study, the specimens were imaged in an area of 13 mm Â 12 mm with a pixel size of 50 lm.…”

Section: Methodsmentioning

confidence: 99%

Spatiotemporal Characterization of Extracellular Matrix Microstructures in Engineered Tissue: A Whole-Field Spectroscopic Imaging Approach

Özçelikkale

Kim

et al. 2013

Journal of Nanotechnology in Engineering and Medicine

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Quality and functionality of engineered tissues are closely related to the microstructures and integrity of their extracellular matrix (ECM). However, currently available methods for characterizing ECM structures are often labor-intensive, destructive, and limited to a small fraction of the total area. These methods are also inappropriate for assessing temporal variations in ECM structures. In this study, to overcome these limitations and challenges, we propose an elastic light scattering approach to spatiotemporally assess ECM microstructures in a relatively large area in a nondestructive manner. To demonstrate its feasibility, we analyze spectroscopic imaging data obtained from acellular collagen scaffolds and dermal equivalents as model ECM structures. For spatial characterization, acellular scaffolds are examined after a freeze/thaw process mimicking a cryopreservation procedure to quantify freezing-induced structural changes in the collagen matrix. We further analyze spatial and temporal changes in ECM structures during cell-driven compaction in dermal equivalents. The results show that spectral dependence of light elastically backscattered from engineered tissue is sensitively associated with alterations in ECM microstructures. In particular, a spectral decay rate over the wavelength can serve as an indicator for the pore size changes in ECM structures, which are at nanometer scale. A decrease in the spectral decay rate suggests enlarged pore sizes of ECM structures. The combination of this approach with a whole-field imaging platform further allows visualization of spatial heterogeneity of EMC microstructures in engineered tissues. This demonstrates the feasibility of the proposed method that nano- and micrometer scale alteration of the ECM structure can be detected and visualized at a whole-field level. Thus, we envision that this spectroscopic imaging approach could potentially serve as an effective characterization tool to nondestructively, accurately, and rapidly quantify ECM microstructures in engineered tissue in a large area.

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Diffuse light suppression of back-directional gating imaging in high anisotropic media

Cited by 10 publications

References 9 publications

Spectroscopic visualization of nanoscale deformation in bone: interaction of light with partially disordered nanostructure

Spectroscopic visualization of nanoscale deformation in bone: interaction of light with partially disordered nanostructure

Spatiotemporal Assessments of Dermal Hyperemia Enable Accurate Prediction of Experimental Cutaneous Carcinogenesis as well as Chemopreventive Activity

Spatiotemporal Characterization of Extracellular Matrix Microstructures in Engineered Tissue: A Whole-Field Spectroscopic Imaging Approach

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