42 research outputs found
Blur resolved OCT: full-range interferometric synthetic aperture microscopy through dispersion encoding
We present a computational method for full-range interferometric synthetic
aperture microscopy (ISAM) under dispersion encoding. With this, one can
effectively double the depth range of optical coherence tomography (OCT),
whilst dramatically enhancing the spatial resolution away from the focal plane.
To this end, we propose a model-based iterative reconstruction (MBIR) method,
where ISAM is directly considered in an optimization approach, and we make the
discovery that sparsity promoting regularization effectively recovers the
full-range signal. Within this work, we adopt an optimal nonuniform discrete
fast Fourier transform (NUFFT) implementation of ISAM, which is both fast and
numerically stable throughout iterations. We validate our method with several
complex samples, scanned with a commercial SD-OCT system with no hardware
modification. With this, we both demonstrate full-range ISAM imaging, and
significantly outperform combinations of existing methods.Comment: 17 pages, 7 figures. The images have been compressed for arxiv -
please follow DOI for full resolutio
Impedance-optical Dual-modal Cell Culture Imaging with Learning-based Information Fusion
While Electrical Impedance Tomography (EIT) has found many biomedicine
applications, a better resolution is needed to provide quantitative analysis
for tissue engineering and regenerative medicine. This paper proposes an
impedance-optical dual-modal imaging framework, which is mainly aimed at
high-quality 3D cell culture imaging and can be extended to other tissue
engineering applications. The framework comprises three components, i.e., an
impedance-optical dual-modal sensor, the guidance image processing algorithm,
and a deep learning model named multi-scale feature cross fusion network
(MSFCF-Net) for information fusion. The MSFCF-Net has two inputs, i.e., the EIT
measurement and a binary mask image generated by the guidance image processing
algorithm, whose input is an RGB microscopic image. The network then
effectively fuses the information from the two different imaging modalities and
generates the final conductivity image. We assess the performance of the
proposed dual-modal framework by numerical simulation and MCF-7 cell imaging
experiments. The results show that the proposed method could significantly
improve image quality, indicating that impedance-optical joint imaging has the
potential to reveal the structural and functional information of tissue-level
targets simultaneously
Quantitative Action Spectroscopy Reveals ARPE-19 Sensitivity to Long-Wave 1 Ultraviolet Radiation at 350 nm and 380 nm
The role of ultraviolet radiation (UVR) exposure in the aetiology of retinal degeneration has been debated for decades with epidemiological evidence failing to find a clear consensus for or against it playing a role. A key reason for this is a lack of foundational research into the response of living retinal tissue to UVR in regard to modern ageing-specific parameters of tissue function. We therefore explored the response of cultured retinal pigmented epithelium (RPE), the loss of which heralds advanced visual decline, to specific wavelengths of UVR across the UV-B and UV-A bands found in natural sunlight. Using a bespoke in vitro UVR exposure apparatus coupled with bandpass filters we exposed the immortalised RPE cell line, ARPE-19, to 10Â nm bands of UVR between 290 and 405Â nm. Physical cell dynamics were assessed during exposure in cells cultured upon specialist electrode culture plates which allow for continuous, non-invasive electrostatic interrogation of key cell parameters during exposure such as monolayer coverage and tight-junction integrity. UVR exposures were also utilised to quantify wavelength-specific effects using a rapid cell viability assay and a phenotypic profiling assay which was leveraged to simultaneously quantify intracellular reactive oxygen species (ROS), nuclear morphology, mitochondrial stress, epithelial integrity and cell viability as part of a phenotypic profiling approach to quantifying the effects of UVR. Electrical impedance assessment revealed unforeseen detrimental effects of UV-A, beginning at 350Â nm, alongside previously demonstrated UV-B impacts. Cell viability analysis also highlighted increased effects at 350Â nm as well as 380Â nm. Effects at 350Â nm were further substantiated by high content image analysis which highlighted increased mitochondrial dysfunction and oxidative stress. We conclude that ARPE-19 cells exhibit a previously uncharacterised sensitivity to UV-A radiation, specifically at 350Â nm and somewhat less at 380Â nm. If upheld in vivo, such sensitivity will have impacts upon geoepidemiological risk scoring of macular sensitivity
Exploring the Potential of Electrical Impedance Tomography for Tissue Engineering Applications
In tissue engineering, cells are generally cultured in biomaterials to generate three-dimensional artificial tissues to repair or replace damaged parts and re-establish normal functions of the body. Characterizing cell growth and viability in these bioscaffolds is challenging, and is currently achieved by destructive end-point biological assays. In this study, we explore the potential to use electrical impedance tomography (EIT) as a label-free and non-destructive technology to assess cell growth and viability. The key challenge in the tissue engineering application is to detect the small change of conductivity associated with sparse cell distributions in regards to the size of the hosting scaffold, i.e., low volume fraction, until they assemble into a larger tissue-like structure. We show proof-of-principle data, measure cells within both a hydrogel and a microporous scaffold with an ad-hoc EIT equipment, and introduce the frequency difference technique to improve the reconstruction