Anemia associated with intestinal parasites and malnutrition is the leading cause of morbidity and mortality in small ruminants worldwide. Qualitative scoring of conjunctival redness has been developed so that farmers can gauge anemia in sheep and goats to identify animals that require treatment. For clinically relevant anemia diagnosis, complete blood count-comparable quantitative methods often rely on complicated and expensive optical instruments, requiring detailed spectral information of hemoglobin. We report experimental and numerical results for simple, yet reliable, noninvasive hemoglobin detection that can be correlated with laboratory-based blood hemoglobin testing for anemia diagnosis. In our pilot animal study using calves, we exploit the third eyelid (i.e., palpebral conjunctiva) as an effective sensing site. To further test spectrometer-free (or spectrometerless) hemoglobin assessments, we implement full spectral reconstruction from RGB data and partial least square regression. The unique combination of RGB-based spectral reconstruction and partial least square regression could potentially offer uncomplicated instrumentation and avoid the use of a spectrometer, which is vital for realizing a compact and inexpensive hematology device for quantitative anemia detection in the farm field.
We demonstrate that a spatial and temporal analysis of subclinical hyperemia reliably predicts specific areas at high risk
for skin tumor development during photocarcinogenesis. To determine detailed spatiotemporal patterns of inflammatory
angiogenesis foci in a relatively large area, we developed a mesoscopic (between microscopic and macroscopic) imaging
approach. This method relies on our earlier finding that the combination of a spectral analysis of hemoglobin with
diffuse-light-suppressed imaging can increase the image resolution, contrast and penetration depth to visualize
microvasculature Hgb content in the large tissue area. In our recent study, SKH1 hairless albino mice were irradiated
for 10 weeks with a carcinogen dose of UVB. Using our newly developed mesoscopic imaging methods, we imaged
the mice over 20 - 30 weeks after stopping UVB, and excised hyperemic/non-hyperemic areas at several different timepoints.
We show that persistent hyperemic foci can predict future tumor formation. In particular, our imaging approach
allows us to assess the spatial and temporal extent of subclinical inflammatory foci, which in turn can predict sites of
future overlying tumor formation. In addition, although COX-2 inhibitors are known to suppress skin cancer
development in humans, it remains unclear whether the chemopreventive activity of COX-2 inhibitors are chiefly
attributable to their anti-inflammatory effects. Our study provides evidence that subclinical subepithelial inflammatory
foci occur prior to overt tumor formation, and that these areas are highly predictive for future tumor formation, that
celecoxib’s ability to suppress tumorigenesis is tightly linked to its ability to reduce the area of subclinical inflammatory
foci.
We report that when tissue images are formed via a small solid angle in the backward direction (i.e., back-directional gating), the image intensity is dominantly determined by tissue scattering anisotropy. Thus, this configuration allows for scattering anisotropy-weighted imaging that can provide an intrinsic contrast by capturing tissue structures and organizations. To demonstrate the immediate feasibility, we apply scattering anisotropy-weighted imaging to tissue blocks including basal-cell carcinomas as a pilot study. The main feature of our imaging approach is the high sensitivity to tumor locations and the simplicity for large-area visualization. We further envision that scattering anisotropy-weighted imaging could potentially be used to visualize tissue microenvironments in a mesoscopic (between microscopic and macroscopic) imaging setting.
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.
We experimentally study potential mechanisms by which the enhancement factor in low-coherence enhanced backscattering (LEBS) can probe subtle variations in radial intensity distribution in weakly scattering media. We use enhanced backscattering of light by implementing either (1) low spatial coherence illumination or (2) multiple spatially independent detections using a microlens array under spatially coherent illumination. We show that the enhancement factor in these configurations is a measure of the integrated intensity within the localized coherence or detection area, which can exhibit strong dependence on small perturbations in scattering properties. To further evaluate the utility of the LEBS enhancement factor, we use a well-established animal model of cutaneous two-stage chemical carcinogenesis. In this pilot study, we demonstrate that the LEBS enhancement factor can be substantially altered at a stage of preneoplasia. Our animal result supports the idea that early carcinogenesis can cause subtle alterations in the scattering properties that can be captured by the LEBS enhancement factor. Thus, the LEBS enhancement factor has the potential as an easily measurable biomarker in skin carcinogenesis.
A unique optical property of biological tissue is high anisotropy so that light is scattered in the same direction with
respect to the incident direction. We demonstrate that simple back-directional gating allows us to take advantage of such
an intrinsic property of biological tissue to significantly suppress unwanted diffuse light. In back-directional gated
imaging, the high anisotropic property of the surrounding medium can serve as a waveguide in a moderate depth.
Although this idea is straightforward, it has not been utilized for diffuse light suppression and imaging quality
improvement such as contrast and resolution in large-area imaging for biological tissue. We further show that by
combining a spectral analysis with back-directional gated imaging, image contrast and depth can be dramatically
enhanced for visualizing stromal microvascular blood content in a relatively large area. Because microvasculature can be
heterogeneous, our imaging approach can permit detailed visualization of microvascularity in a relatively large area up
to ~20 mm x 20 mm.
We demonstrate an alternative yet effective approach for spatial gating without mechanical pinhole scanning. We take
advantage of the intrinsic property of the robust self-interference effect of low-coherence enhanced backscattering under
low spatial coherence illumination. The unique combination of low spatial coherence illumination and differential angle
imaging permits the implementation of multiple independent virtual pinholes into a large area imaging platform. Thus,
our imaging approach substantially minimizes cross-talk among adjacent pixels, rejects the background light caused by
out-of-plane scattered light, and thereby enhances image contrast and resolution.
We experimentally demonstrate that back-directional gating in an imaging setup can potentially remove unwanted diffuse light to improve the contrast of an object embedded in a high anisotropic surrounding medium. In such back-directional gating, the high anisotropic property of the surrounding medium can serve as a waveguide to deliver the incident light to the embedded object and to isolate the ballistic or snake-like light backscattered from the object in a moderate depth. We further discuss the effects of back-directional gating in the image formation in terms of the image resolution and the depth of field. Although backscattering detections of biological tissue have recently received considerable attention, we, for the first time to our knowledge, show its potential advantage for the contrast improvement in high anisotropic media.
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