Development of a multimodal foveated endomicroscope for the detection of oral cancer

Cardiac tropoini T (TNNT2) plays a potential oncogenic role in colorectal carcinogenesis

PURPOSE

Colorectal cancer (CRC) is the third most common cancer in the world. The purpose of this study was to investigate the role of TNNT2 in the proliferation, migration and invasion of CRC cells and its expression in CRC tissues to better understand the regulatory role of TNNT2 in CRC.

METHODS

Western blotting (WB) and qPCR were used to detect the expression of TNNT2 in colorectal cancer tissues and paracancerous tissues. CCK-8, colony formation, Transwell and other experiments were used to clarify the role of TNNT2 in the proliferation, migration and invasion of colorectal cancer cells. Changes in TNNT2, EGFR and HER2 mRNA transcription levels were detected by SYBR Real-Time PCR assay, and the effects of TNNT2 overexpression or knockdown on the expression of EGFR, HER2 and EMT-related proteins in CRC cells were determined by WB. TNNT2 and EGFR intreaction was carried out in HCT116 cells by coimmunoprecipitation experiments.

RESULTS

The protein and mRNA expression level of TNNT2 in CRC tissues were higher than those in paracancerous tissues. The CCK-8 results suggested that overexpression of TNNT2 significantly promoted the proliferation of HCT116 and RKO cells, and TNNT2 konckdown gets the opposite result; and the colony formation results were the same as tthose of CCK-8 assay. Transwell invasion and migration experiments showed that overexpression of TNNT2 promoted the migration and invasion of HCT116 and PKO cells, and TNNT2 konckdown suppressed the migration and invasion of the these cells. The SYBR Green I real-time PCR method revealed that them RNA levels of TNNT2, EGFR and HER2 in the TNNT2 overexpression group were higher than those in RKO cells. WB showed that overexpressing TNNT2 increased the expression of EGFR and HER2 in HCT16 and RKO cells,decreased the expression of EMT marker E-cadherin, and increased the expression of Vimentin and N-cadherin. Konckdown of TNNT2 decreased the expression of EGFR and HER2, increased the expression of E-cadherin, and decreased the expression of Vimentin and N-cadherin in HCT16 and RKO cells. The immunocoprecipitation experiment showed that there was an interaction between EGFR and TNNT2.

CONCLUSION

TNNT2 can promote the proliferation, invasion and metastasis of colorectal cancer cells. There is an interaction between TNNT2 and EGFR protein. TNNT2 can upregulate EGFR and HER2-related proteins in colorectal cancer cells and promote the occurrence of EMT. Therefore, TNNT2 can promote the invasion and metastasis of CRC cells through the EGFR/HER2/EMT signal axis, suggesting that TNNT2 is a potential target of CRC treatment.

Hybrid non-sequential modeling of an image mapping spectrometer

An image mapping spectrometer (IMS) is a kind of snapshot imaging spectrometer characterized by containing several array components including the image mapper, prism array, and reimaging lens array. We propose a hybrid non-sequential modeling method of IMS and present the complete optical model of the system built in Zemax. This method utilizes the spatial periodicity of the array components and requires only a small number of input parameters. Moreover, we design a collimating lens of a large relative aperture, sufficient working distance, and low aberration to meet the requirements of an IMS with good optical performance and compact volume. The designed lens is quantitatively evaluated in the entire IMS model, and the results demonstrate that the lens has excellent optical performance. The evaluation on the collimating lens also demonstrates the capability of the proposed modeling method in the design and optimization of systems such as the IMS that contain multiple array components. The designed collimating lens is manufactured and assembled in the experimental setup of the IMS. The proposed modeling method is verified by experimental results.

Bimodal multispectral imaging system with cloud-based machine learning algorithm for real-time screening and detection of oral potentially malignant lesions and biopsy guidance

SIGNIFICANCE

Screening and early detection of oral potentially malignant lesions (OPMLs) are of great significance in reducing the mortality rates associated with head and neck malignancies. Intra-oral multispectral optical imaging of tissues in conjunction with cloud-based machine learning (CBML) can be used to detect oral precancers at the point-of-care (POC) and guide the clinician to the most malignant site for biopsy.

AIM

Develop a bimodal multispectral imaging system (BMIS) combining tissue autofluorescence and diffuse reflectance (DR) for mapping changes in oxygenated hemoglobin (HbO2) absorption in the oral mucosa, quantifying tissue abnormalities, and guiding biopsies.

APPROACH

The hand-held widefield BMIS consisting of LEDs emitting at 405, 545, 575, and 610 nm, 5MPx monochrome camera, and proprietary Windows-based software was developed for image capture, processing, and analytics. The DR image ratio (R610/R545) was compared with pathologic classification to develop a CBML algorithm for real-time assessment of tissue status at the POC.

RESULTS

Sensitivity of 97.5% and specificity of 92.5% were achieved for discrimination of OPML from patient normal in 40 sites, whereas 82% sensitivity and 96.6% specificity were obtained for discrimination of abnormal (OPML + SCC) in 89 sites. Site-specific algorithms derived for buccal mucosa (27 sites) showed improved sensitivity and specificity of 96.3% for discrimination of OPML from normal.

CONCLUSIONS

Assessment of oral cancer risk is possible by mapping of HbO2 absorption in tissues, and the BMIS system developed appears to be suitable for biopsy guidance and early detection of oral cancers.

Improvement in optical fiber bundle-based imaging using synchronized fiber motion

Image quality in fiber bundle-based imaging systems is inherently limited by the size and spacing of the individual fiber cores. The fiber bundle limits the achievable spatial resolution and superimposes a fixed pattern of signal variability across the image. To overcome these limitations, piezoelectric tubes were used to synchronously dither the fiber bundle on both ends. Experimental results using the dithering approach with a commercial fiber bundle showed a substantial decrease in fixed pattern noise and an increase in spatial resolution.

Hyperspectral Imaging and the Retina: Worth the Wave?

Purpose

Hyperspectral imaging is gaining attention in the biomedical field because it generates additional spectral information to study physiological and clinical processes. Several technologies have been described; however an independent, systematic literature overview is lacking, especially in the field of ophthalmology. This investigation is the first to systematically overview scientific literature specifically regarding retinal hyperspectral imaging.

Methods

A systematic literature review was conducted, in accordance with PRISMA Statement 2009 criteria, in four bibliographic databases: Medline, Embase, Cochrane Database of Systematic Reviews, and Web of Science.

Results

Fifty-six articles were found that meet the review criteria. A range of techniques was reported: Fourier analysis, liquid crystal tunable filters, tunable laser sources, dual-slit monochromators, dispersive prisms and gratings, computed tomography, fiber optics, and Fabry-Perrot cavity filter covered complementary metal oxide semiconductor. We present a narrative synthesis and summary tables of findings of the included articles, because methodologic heterogeneity and diverse research topics prevented a meta-analysis being conducted.

Conclusions

Application in ophthalmology is still in its infancy. Most previous experiments have been performed in the field of retinal oximetry, providing valuable information in the diagnosis and monitoring of various ocular diseases. To date, none of these applications have graduated to clinical practice owing to the lack of sufficiently large validation studies.

Translational Relevance

Given the promising results that smaller studies show for hyperspectral imaging (e.g., in Alzheimer's disease), advanced research in larger validation studies is warranted to determine its true clinical potential.

Surgical spectral imaging

Recent technological developments have resulted in the availability of miniaturised spectral imaging sensors capable of operating in the multi- (MSI) and hyperspectral imaging (HSI) regimes. Simultaneous advances in image-processing techniques and artificial intelligence (AI), especially in machine learning and deep learning, have made these data-rich modalities highly attractive as a means of extracting biological information non-destructively. Surgery in particular is poised to benefit from this, as spectrally-resolved tissue optical properties can offer enhanced contrast as well as diagnostic and guidance information during interventions. This is particularly relevant for procedures where inherent contrast is low under standard white light visualisation. This review summarises recent work in surgical spectral imaging (SSI) techniques, taken from Pubmed, Google Scholar and arXiv searches spanning the period 2013-2019. New hardware, optimised for use in both open and minimally-invasive surgery (MIS), is described, and recent commercial activity is summarised. Computational approaches to extract spectral information from conventional colour images are reviewed, as tip-mounted cameras become more commonplace in MIS. Model-based and machine learning methods of data analysis are discussed in addition to simulation, phantom and clinical validation experiments. A wide variety of surgical pilot studies are reported but it is apparent that further work is needed to quantify the clinical value of MSI/HSI. The current trend toward data-driven analysis emphasises the importance of widely-available, standardised spectral imaging datasets, which will aid understanding of variability across organs and patients, and drive clinical translation.

Wave-vector-encoded nonlinear endomicroscopy

Based on a rigid square fiber for wave vector delivery, we present a novel (to the best of our knowledge) wave-vector-encoded nonlinear-optical endomicroscopy (WENE). WENE overcomes three tangled issues, including femtosecond pulse broadening induced signal degradation, complexity of packaging miniaturized scanners in the distal end, and pixel-like images, which cannot be fully addressed by current distal scanning nonlinear endomicroscopy (NE) or fiber-bundle-based proximal scanning NE. Due to the advantages of its simplicity in overall configuration and package in the distal end, the capability of addressing the issue of pulse broadening, and offering continuous wave vector delivery, the demonstrated WENE shows great promise for future basic research on biomedical processes and minimally invasive utilization for clinical diagnosis.

Accurate ray tracing model of an imaging system based on image mapper

The image mapper plays a key role in the imaging process of the image mapping spectrometer (IMS), which is a snapshot imaging spectrometer with superiority in light throughput, temporal resolution, and compactness. In this paper, an accurate ray tracing model of the imaging units of the IMS, especially the image mapper, is presented in the form of vector operation. Based on the proposed model, the behavior of light reflection on the image mapper is analyzed thoroughly, including the precise position of the reflection point and interaction between adjacent facets. Rigorous spatial correspondence between object points and pixels on the detector is determined by tracing the chief ray of an arbitrary point in the field. The shadowing effect, which is shadowing between adjacent facets and blocking caused by the facets' side walls, is analyzed based on our model. The experimental results verify the fidelity of the model and the existence of the shadowing effect. The research is meaningful for comprehending the imaging mechanism of the IMS and facilitates the design and analysis process in the future.

A Hybrid Non-destructive Measuring Method of Three-dimensional Profile of Through Silicon Vias for Realization of Smart Devices

Smart devices have been fabricated based on design concept of multiple layer structures which require through silicon vias to transfer electric signals between stacked layers. Because even a single defect leads to fail of the packaged devices, the dimensions of the through silicon vias are needed to be measured through whole sampling inspection process. For that, a novel hybrid optical probe working based on optical interferometry, confocal microscopy and optical microscopy was proposed and realized for enhancing inspection efficiency in this report. The optical microscope was utilized for coarsely monitoring the specimen in a large field of view, and the other methods of interferometry and confocal microscopy were used to measure dimensions of small features with high speed by eliminating time-consuming process of the vertical scanning. Owing to the importance of the reliability, the uncertainty evaluation of the proposed method was fulfilled, which offers a practical example for estimating the performance of inspection machines operating with numerous principles at semiconductor manufacturing sites. According to the measurement results, the mean values of the diameter and depth were 40.420 µm and 5.954 µm with the expanded uncertainty of 0.050 µm (k = 2) and 0.208 µm (k = 2), respectively.

Fiber bundle shifting endomicroscopy for high-resolution imaging

Flexible endomicroscopes commonly use coherent fiber bundles with high core densities to facilitate high-resolution in vivo imaging during endoscopic and minimally-invasive procedures. However, under-sampling due to the inter-core spacing limits the spatial resolution, making it difficult to resolve smaller cellular features. Here, we report a compact and rapid piezoelectric transducer (PZT) based bundle-shifting endomicroscopy system in which a super-resolution (SR) image is restored from multiple pixelation-limited images by computational means. A miniaturized PZT tube actuates the fiber bundle behind a GRIN micro-lens and a Delaunay triangulation based algorithm reconstructs an enhanced SR image. To enable real-time cellular-level imaging, imaging is performed using a line-scan confocal laser endomicroscope system with a raw frame rate of 120 fps, delivering up to 2 times spatial resolution improvement for a field of view of 350 µm at a net frame rate of 30 fps. The resolution enhancement is confirmed using resolution phantoms and ex vivo fluorescence endomicroscopy imaging of human breast specimens is demonstrated.

Microscopic investigation of" topically applied nanoparticles for molecular imaging of fresh tissue surfaces

Previous studies have shown that functionalized nanoparticles (NPs) topically applied on fresh tissues are able to rapidly target cell-surface protein biomarkers of cancer. Furthermore, studies have shown that a paired-agent approach, in which an untargeted NP is co-administered with a panel of targeted NPs, controls for the nonspecific behavior of the NPs, enabling quantitative imaging of biomarker expression. However, given the complexities in nonspecific accumulation, diffusion, and chemical binding of targeted NPs in tissues, studies are needed to better understand these processes at the microscopic scale. Here, fresh tissues were stained with a paired-agent approach, frozen, and sectioned to image the depth-dependent accumulation of targeted and untargeted NPs. The ratio of targeted-to-untargeted NP concentrations-a parameter used to distinguish between tumor and benign tissues-was found to diminish with increasing NP diffusion depths due to nonspecific accumulation and poor washout. It was then hypothesized and experimentally demonstrated that larger NPs would exhibit less diffusion below tissue surfaces, enabling higher targeted-to-untargeted NP ratios. In summary, these methods and investigations have enabled the design of NP agents with improved sensitivity and contrast for rapid molecular imaging of fresh tissues.

Multiplexed Optical Imaging of Tumor-Directed Nanoparticles: A Review of Imaging Systems and Approaches

In recent decades, various classes of nanoparticles have been developed for optical imaging of cancers. Many of these nanoparticles are designed to specifically target tumor sites, and specific cancer biomarkers, to facilitate the visualization of tumors. However, one challenge for accurate detection of tumors is that the molecular profiles of most cancers vary greatly between patients as well as spatially and temporally within a single tumor mass. To overcome this challenge, certain nanoparticles and imaging systems have been developed to enable multiplexed imaging of large panels of cancer biomarkers. Multiplexed molecular imaging can potentially enable sensitive tumor detection, precise delineation of tumors during interventional procedures, and the prediction/monitoring of therapy response. In this review, we summarize recent advances in systems that have been developed for the imaging of optical nanoparticles that can be heavily multiplexed, which include surface-enhanced Raman-scattering nanoparticles (SERS NPs) and quantum dots (QDs). In addition to surveying the optical properties of these various types of nanoparticles, and the most-popular multiplexed imaging approaches that have been employed, representative preclinical and clinical imaging studies are also highlighted.