A biopsy is often performed for the diagnosis of cancer during a surgical operation. In addition, pathological biopsy is required to discriminate the margin between cancer tissues and normal tissues ...in surgical specimens. In this study, we presented a novel method for discriminating between tumor and normal tissues using fluorescence lifetime endoscopy (FLE). We demonstrated the relationship between the fluorescence lifetime and pH in fluorescein using the proposed fluorescence lifetime measurement system. We also showed that cancer could be diagnosed based on this relationship by assessing differences in pH based fluorescence lifetime between cancer and normal tissues using two different types of tumor such as breast tumors (MDA-MB-361) and skin tumors (A375), where cancer tissues have ranged in pH from 4.5 to 7.0 and normal tissues have ranged in pH from 7.0 to 7.4. To support this approach, we performed hematoxylin and eosin (H&E) staining test of normal and cancer tissues within a certain area. From these results, we showed the ability to diagnose a cancer using FLE technique, which were consistent with the diagnosis of a cancer with H&E staining test. In summary, the proposed pH-based FLE technique could provide a real time, in vivo, and in-situ clinical diagnostic method for the cancer surgical and could be presented as an alternative to biopsy procedures.
In this study, we developed a digital shade-matching device for dental color determination using the support vector machine (SVM) algorithm. Shade-matching was performed using shade tabs. For the ...hardware, the typically used intraoral camera was modified to apply the cross-polarization scheme and block the light from outside, which can lead to shade-matching errors. For reliable experiments, a precise robot arm with ±0.1 mm position repeatability and a specially designed jig to fix the position of the VITA 3D-master (3D) shade tabs were used. For consistent color performance, color calibration was performed with five standard colors having color values as the mean color values of the five shade tabs of the 3D. By using the SVM algorithm, hyperplanes and support vectors for 3D shade tabs were obtained with a database organized using five developed devices. Subsequently, shade matching was performed by measuring 3D shade tabs, as opposed to real teeth, with three additional devices. On average, more than 90% matching accuracy and a less than 1% failure rate were achieved with all devices for 10 measurements. In addition, we compared the classification algorithm with other classification algorithms, such as logistic regression, random forest, and k-nearest neighbors, using the leave-pair-out cross-validation method to verify the classification performance of the SVM algorithm. Our proposed scheme can be an optimum solution for the quantitative measurement of tooth color with high accuracy.
Confocal endomicroscopy is a powerful tool for in vivo real-time imaging at cellular resolution inside a living body without tissue resection. Microscopic fluorescence lifetime measurement can ...provide information about localized biochemical conditions such as pH and the concentrations of oxygen and calcium. We hypothesized that combining these techniques could assist accurate cancer discrimination by providing both biochemical and morphological information. We designed a dual-mode experimental setup for confocal endomicroscopic imaging and fluorescence lifetime measurement and applied it to a mouse xenograft model of activated human pancreatic cancer generated by subcutaneous injection of AsPC-1 tumor cells. Using this method with pH-sensitive sodium fluorescein injection, we demonstrated discrimination between normal and cancerous tissues in a living mouse. With further development, this method may be useful for clinical cancer detection.
•We examined distributive equity based on the use of green spaces.•Access to local parks decreased as the percentage of the elderly population increased.•Local park use increased as the percentage of ...children and the elderly increased.•The results suggest that access and use can be different for the same group.•Mobility data provide novel insights for park visit behavior.
Previous green space equity studies have relied on access measures, such as the distance to, number of, or size of green spaces and have produced mixed results on green space disparities in the U.S. While the benefits of green spaces can be fulfilled when people visit them, attention to the differential use of green spaces has been less common. We examined green space inequalities using traditional access measures in order to understand which group has lower access to local parks and then investigated which urban residents visit local parks more using SafeGraph’s mobility data. We found that the Phoenix metro area experiences green space access disparities by age group and (partially) income rather than by race and ethnicity. Access to local parks consistently decreased as the percentage of the elderly population increased in a neighborhood. However, the visit to local parks consistently increased as the percentage of children and the elderly increased. We discuss the implications of our findings for urban planning.
Background and Objectives
Optical coherence tomography (OCT) is a cross‐sectional imaging method utilizing a low coherence interferometry. The lateral resolution of the OCT is limited by the ...numerical aperture (NA) of the imaging lens. Using a high NA lens improves the lateral resolution but reduces the depth of focus (DOF). In this study, we propose a method to improve the lateral resolution of OCT images by end‐to‐end training of a deep 1‐D deconvolution network without use of high‐resolution images.
Materials and Methods
To improve the lateral resolution of the OCT, we trained the 1‐D deconvolution network using lateral profiles of OCT images and the beam spot size. We used our image‐guided laparoscopic surgical tool (IGLaST) to acquire OCT images of nonbiological and biological samples ex vivo. The OCT images were then blurred by applying Gaussian functions with various full width half maximums ranging from 40 to 160 µm. The network was trained using the blurred OCT images as input and the non‐blurred original OCT images as output. We quantitatively evaluated the developed network in terms of similarity and signal‐to‐ratio (SNR), using in‐vivo images of mesenteric tissue from a porcine model that was not used for training. In addition, we performed knife‐edge tests and qualitative evaluation of the network to show the lateral resolution improvement of ex‐vivo and in‐vivo OCT images.
Results
The proposed method showed an improvement of image quality on both blurred images and non‐blurred images. When the proposed deconvolution network was applied, the similarity to the non‐blurred image was improved by 1.29 times, and the SNR was improved by 1.76 dB compared to the artificially blurred images, which was superior to the conventional deconvolution method. The knife‐edge tests at distances at 200 to 1000 µm from the imaging probe showed an approximately 1.2 times improvement in lateral resolution. In addition, through qualitative evaluation, it was found that the image quality of both ex‐vivo and in‐vivo tissue images was improved with clear structure and less noise.
Conclusions
This study showed the ability of the 1‐D deconvolution network to improve the image quality of OCT images with variable lateral resolution. We were able to train the network with a small amount of data by constraining the network in 1‐D. The quantitative evaluation showed better results than conventional deconvolution methods for various amount of blurring. Qualitative evaluation showed analogous results with quantitative results. This simple yet powerful image restoration method provides improved lateral resolution and suppresses background noise, making it applicable to a variety of OCT imaging applications.
We demonstrated GPU accelerated real-time confocal fluorescence lifetime imaging microscopy (FLIM) based on the analog mean-delay (AMD) method. The frame rate of our system was demonstrated to be 13 ...fps for a 200 × 200 pixel image when observing maize vascular tissue. This system can be utilized for studying spectroscopic characteristics of cancer tissues.
Urban green and blue spaces provide mental and physical health benefits for their surrounding communities, but the key to many of these benefits is the utilization of the urban greenspace for ...recreation or relaxation. For some communities, use is limited by physical access to the greenspace while for other communities, the characteristics of the greenspace play an important role in encouraging or discouraging use. What drives communities to use their local greenspace with respect to all other available greenspace in an urban area remains an underexplored question. To fill this gap, we leverage a large human mobility dataset to track a year of park visitation by residents across the Phoenix, AZ, metropolitan area combined with a spatial autoregressive model using spatially lagged dependent variables. Our results suggest that it is not vegetation but the presence of water features within a park that encourages higher visitation to local parks. Water features also influence visitation to parks outside a communities local area; its presence within a local park decreased how often individuals visited non-local parks as a proportion of their total park visitation. We discuss the implications of these finding in the context of a desert city that lacks both greenspace and water.
We present a new high-speed lifetime measurement scheme of analog mean-delay (AMD) method which is suitable for studying dynamical time-resolved spectroscopy and high-speed fluorescence lifetime ...imaging microscopy (FLIM). In our lifetime measurement method, the time-domain intensity signal of a fluorescence decay is acquired as an analog waveform. And the lifetime information is extracted from the mean temporal delay of the acquired signal. Since this method does not rely on the single-photon counting technique, the signals of multiple fluorescence photons can be acquired simultaneously. The measurement speed can be increased easily by raising the fluorescence intensity without a photon-rate limit. We have investigated various characteristics of our method in lifetime accuracy and precision as well as measurement speed. It has been found that our method can provide excellent measurement performances in various aspects. We hav demonstrated a high-speed measurement with a high photon detection rate of approximately 108 photons per second with a nearly shot noise-limited photon economy. A fluorescence lifetime of 3.2 ns was accurately determined with a standard deviation of 3% from the data acquired within 17.8 micros at a rate of 56,300 lifetime determinations per second.
We demonstrated GPU accelerated real-time confocal fluorescence lifetime imaging microscopy (FLIM) based on the analog mean-delay (AMD) method. Our algorithm was verified for various fluorescence ...lifetimes and photon numbers. The GPU processing time was faster than the physical scanning time for images up to 800 × 800, and more than 149 times faster than a single core CPU. The frame rate of our system was demonstrated to be 13 fps for a 200 × 200 pixel image when observing maize vascular tissue. This system can be utilized for observing dynamic biological reactions, medical diagnosis, and real-time industrial inspection.
A redox-responsive specific theranostic agent was developed by the conjugation of photosensitizers with the tryptophan-containing GE11 peptide via a cleavable disulfide linker. It showed a potential ...utility for the target-cell-specific activatable fluorescence imaging and photodynamic therapy of triple-negative breast cancers.
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