Image Research Articles

Imaging dendrite growth in solid-state sodium batteries using fluorescence tomography technology.

Dendrite growth in solid-state sodium batteries (SSBs) is one of the most concerned issues that critically affect the battery efficiency and cycling performance. Here, by designing a fluorescent Eu3+-doped Na3Zr2Si2PO12 solid electrolyte (SE) to facilitate three-dimensional (3D) optical imaging on a confocal laser scanning microscopy, a fluorescence tomography (FT) method is developed for observing the sodium dendrite growth during charge/discharge cycles of the SSBs in a 3D view. It is quantitatively revealed that small-size sodium islands appear after several cycles, and with the cycles increasing, large-size dendrites in tens of micrometers gradually form until a critical sodium dendrite volume arrives where a short circuit or severe performance deterioration occurs. Furthermore, by regulating the Eu3+ doping ratio, a record-high sodium plating/stripping cycling stability for more than 1 year (487.5 days) is achieved at 25°C. This work demonstrates an FT method observing sodium dendrite growth in SSBs and will promote the functional design of high-performance SEs.

Asymmetric choroidal vascular pattern in tilted disc syndrome.

To observe the choroidal vasculature in patients with tilted disc syndrome (TDS) using en face optical coherence tomography (OCT) and to evaluate the symmetry of the choroidal vascular pattern in the macular area. En face OCT was performed using a Plex Elite 9000 (Zeiss) with a 12 × 12mm image of the macula, which was flattened with retinal pigment epithelium and segmented into choroidal layers. The middle/large choroidal vessels were evaluated for vertical symmetry qualitatively by the retina specialist coauthors and quantitatively by binarization analysis of choroidal vessel density and mean vessel diameter. The 2 cases and 4 eyes (19.0%) that were difficult to segment due to the severe slope of the macular area were excluded. Of the 17 eyes in the remaining 13 cases, asymmetric middle/large choroidal vessels were observed in all eyes. Vessel density (P = 0.01) and mean vessel diameter (P < 0.01) of the choroidal middle/large vessels were significantly higher in the superior than in the inferior choroidal segmentation. Serous retinal detachment was observed in 4 eyes, all asymmetric cases. Vertical asymmetry of the middle and large choroidal vessels is observed in most TDS patients. Circulatory imbalance due to choroidal vascular abnormalities in TDS may be one of the causes of serous retinal detachment. What is known: Tilted disc syndrome is the congenital disease with ocular morphologic abnormalities associated with incomplete closure of the embryonic fissure of the eye at the inferior optic nerve head Vertical cross-sectional optical coherence tomography images revealed that the choroid above the macula in tilted disc syndrome is relatively thickened, whereas the choroid within the inferior staphyloma is thinning. Evaluation of choroidal vascularity in tilted disc syndrome by en face optical coherence tomography revealed qualitatively and quantitatively highly dense choroidal vessels in the superior region, with larger diameter choroidal vessels than in the inferior region, and vertical asymmetry with an upward predominance. Choroidal circulatory imbalance due to vertical asymmetry of the choroidal vessels may be one of the causes of serous retinal detachment in tilted disc syndrome.

MEMS-metasurface-enabled mode-switchable vortex lasers.

Compared to conventional lasers limited to generating static modes, mode-switchable lasers equipped with adjustable optics significantly enhance the flexibility and versatility of coherent light sources. However, most current approaches to achieving mode-switchable lasers depend on conventional, i.e., inherently bulky and slow, optical components. Here, we demonstrate fiber lasers empowered by electrically actuated intracavity microelectromechanical system (MEMS)-based optical metasurface (MEMS-OMS) enabling mode switching between fundamental Gaussian and vortex modes at ~1030 nm. By finely adjusting the voltage applied to the MEMS mirror, high-contrast switching between Gaussian (l = 0) and vortex (l = 1, 2, 3, and 5, depending on the OMS arrangement) laser modes is achieved, featuring high mode purities (>95%) and fast responses (~100 microseconds). The proposed intracavity MEMS-OMS-enabled laser configuration provides an at-source solution for generating high-purity fast-switchable laser modes, with potential applications ranging from advanced optical imaging to optical tweezers, optical machining, and intelligent photonics.

Improved ion detection sensitivity in mass spectrometry imaging using tapping-mode scanning probe electrospray ionization to visualize localized lipids in mouse testes.

Mass spectrometry imaging (MSI) is a promising analytical method to visualize the distribution of lipids in biological tissues. To clarify the relationship between cellular distribution and lipid types in a tissue, it is crucial to achieve both an improvement in ion detection sensitivity and a reduction in the ionization area. We report methods for improving the efficiency of ion transfer to a mass spectrometer and miniaturizing the extraction area of a sample for tapping-mode scanning probe electrospray ionization (t-SPESI), atmospheric pressure sampling, and ionization methods. To verify the efficacy of the new t-SPESI measurement system, MSI was performed on mouse testes with a pixel size of 5µm. Lipid images of the testes from wild-type (WT) and lysophospholipid acyltransferase 3 (LPLAT3) knockout mice revealed the characteristic distribution of docosahexaenoic acid-containing phospholipids (DHA-PLs). A comparison of the ion images obtained by MSI and optical images of the same tissues stained with hematoxylin and eosin suggested that the distribution of DHA-PLs was significantly altered by spermatogenesis in the WT mouse testes.

Single-cell electro-mechanical shear flow deformability cytometry

The complex structural and molecular features of a cell lead to a set of specific dielectric and mechanical properties which can serve as intrinsic phenotypic markers that enable different cell populations to be characterised and distinguished. We have developed a microfluidic technique that exploits non-contact shear flow deformability cytometry to simultaneously characterise both the electrical and mechanical properties of single cells at high speed. Cells flow along a microchannel and are deformed (elongated) to different degrees by the shear force created by a viscoelastic fluid and channel wall. The electrical impedance of each cell is measured using sets of integrated microelectrodes along two orthogonal axes to determine the shape change and thus the electrical deformability, together with cell dielectric properties. The system performance was evaluated by measuring the electro-mechanical properties of cells treated in different ways, including osmotic shock, glutaraldehyde cross-linking and cytoskeletal disruption with Cytochalasin D and Latrunculin B. To confirm the accuracy of the system images of deformed cells were also captured using a camera. Correlation between the optical deformability and the electrical deformability is excellent. This novel cytometer has a throughput of ~100 cells s—1 is simple, does not use sheath flow or require high speed optical imaging.

Genetic diagnosis of peripheral blood interleukin-1 in premature infants based on bioinformatics and optical imaging

Preterm labor is a severe health concern among expectant mothers, affecting approximately 5 % to 7 % of all pregnancies worldwide, and is associated with various factors, including genes, peripheral blood, and immunological functions. In our study, we examined the role of familial genetics in preterm labor to address knowledge gaps and provide more evidence on the concept. We searched the GEO database for applicable genes and found that the GSE26315 and GSE73685 series were relevant. We then performed an analysis using the GEO2R, GEPIA2, STRING, and KEGG enrichment pathways. Our findings are consistent with the literature regarding the association between preterm birth and familial genetics, peripheral blood, and interleukin-1. Interleukin-1 exploits immunological functions by inducing uterine inflammation, creating an unfavorable environment for fetal survival. Similarly, peripheral blood induces premature labor, with higher levels in the amniotic fluid indicating a higher rate of preterm birth. Inheritance of the familial genes responsible for preterm birth passes down the trait.

An Open Access Resource for Marmoset Neuroscientific Apparatus.

The use of the common marmoset ( Callithrix jacchus ) for neuroscientific inquiry has grown precipitously over the past two decades. Despite windfalls of grant support from funding initiatives in North America, Europe, and Asia to model human brain diseases in the marmoset, marmoset- specific apparatus are of sparse availability from commercial vendors and thus are often developed and reside within individual laboratories. Through our collective research efforts, we have designed and vetted myriad designs for awake or anesthetized magnetic resonance imaging (MRI), positron emission tomography (PET), computed tomography (CT), as well as focused ultrasound (FUS), electrophysiology, optical imaging, surgery, and behavior in marmosets across the age- span. This resource makes these designs openly available, reducing the burden of de novo development across the marmoset field. The computer-aided-design (CAD) files are publicly available through the Marmoset Brain Connectome (MBC) resource ( https://www.marmosetbrainconnectome.org/apparatus/ ) and include dozens of downloadable CAD assemblies, software and online calculators for marmoset neuroscience. In addition, we make available a variety of vetted touchscreen and task-based fMRI code and stimuli. Here, we highlight the online interface and the development and validation of a few yet unpublished resources: Software to automatically extract the head morphology of a marmoset from a CT and produce a 3D printable helmet for awake neuroimaging, and the design and validation of 8-channel and 14- channel receive arrays for imaging deep structures during anatomical and functional MRI.

Unwrap-Net: A deep neural network-based InSAR phase unwrapping method assisted by airborne LiDAR data

In Interferometric Synthetic Aperture Radar (InSAR) data processing, accurately unwrapping the phase is crucial for measuring elevation or deformation. DCNN models such as PhaseNet and PGNet have improved the efficiency and accuracy of phase unwrapping, but they still face challenges such as incomplete multiscale feature learning, high feature redundancy, and reliance on unrealistic datasets. These limitations compromise their effectiveness in areas with low coherence and high gradient deformation. This study proposed Unwrap-Net, a novel network model featuring an encoder-decoder structure and enhanced multiscale feature learning via ASPP (Atrous Spatial Pyramid Pooling). Unwrap-Net minimizes feature redundancy and boosts learning efficiency using SERB (Residual Convolutional with SE-block). For dataset construction, airborne LiDAR terrain data combined with land cover data from optical images, using the SGS (Sequential Gaussian Simulation) method, are used to synthesize phase data and simulate decorrelation noise. This approach creates a dataset that closely approximates real-world conditions. Additionally, the introduction of a new high-fidelity optimization loss function significantly enhances the model’s resistance to noise. Experimental results show that compared to the SNAPHU and PhaseNet models, the SSIM of the Unwrap-Net model improves by over 13%, and the RMSE is reduced by more than 34% in simulated data experiments. In real data experiments, SSIM improves by over 6%, and RMSE is reduced by more than 49%. This indicates that the unwrapping results of the Unwrap-Net model are more reliable and have stronger generalization capabilities. The related experimental code and dataset will be made available at https://github.com/yangwangyangzi48/UNWRAPNETV1.git.

Insights into an indolicidin-derived low-toxic anti-microbial peptide's efficacy against bacterial cells while preserving eukaryotic cell viability.

Antimicrobial peptides (AMPs) are a current solution to combat antibiotic resistance, but they have limitations, including their expensive production process and the induction of cytotoxic effects. We have developed novel AMP candidate (peptide 3.1) based on indolicidin, among the shortest naturally occurring AMP. The antimicrobial activity of this peptide is demonstrated by the minimum inhibitory concentration, while the hemolysis tests and MTT assay indicate its low cytotoxicity. In optical diffraction tomography, red blood cells treated with peptide 3.1 showed no discernible effects, in contrast to indolicidin. However, peptide 3.1 did induce cell lysis in E. coli, leading to a reduced potential for the development of antibiotic resistance. To investigate the mechanism underlying membrane selectivity, the structure of peptide 3.1 was analyzed using nuclear magnetic resonance spectroscopy and molecular dynamics simulations. Peptide 3.1 is structured with an increased distinction between hydrophobic and charged residues and remained in close proximity to the eukaryotic membrane. On the other hand, peptide 3.1 exhibited a disordered conformation when approaching the prokaryotic membrane, similar to indolicidin, leading to its penetration into the membrane. Consequently, it appears that the amphipathicity and structural rigidity of peptide 3.1 contribute to its membrane selectivity. In conclusion, this study may lead to the development of Peptide 3.1, a promising commercial candidate based on its low cost to produce and low cytotoxicity. We have also shed light on the mechanism of action of AMP, which exhibits selective toxicity to bacteria while not damaging eukaryotic cells.

Point spread function deconvolution using a convolutional autoencoder

A major issue in optical astronomical image analysis is the combined effect of the instrument’s point spread function (PSF) and the atmospheric seeing that blurs images and changes their shape in a way that is band and time-of-observation dependent. In this work we present a very simple neural network based approach to nonblind image deconvolution that relies on feeding a convolutional autoencoder (CAE) input images that have been preprocessed by convolution with the corresponding PSF and its regularized inverse, a method which is both conceptually simple and computationally less intensive. We also present here, a new approach for dealing with limited input dynamic range of neural networks compared to the dynamic range present in astronomical images. Published by the American Physical Society 2024

Acute effects of high-intensity interval training on microvascular circulation: a case control study in uveal melanoma

Abstract Objectives The aim of this study was to explore the acute effects of high-intensity interval training (HIIT) on the microvascular circulation and vascular tumor microenvironment (TME) in a patient with uveal melanoma (UM). Additionally, the acceptance of the applied diagnostics and the exercise protocol in a clinical ophthalmic-oncology setting were evaluated. Methods This case-control study included a young adult male patient with UM previously treated with radiation and an age-matched healthy control. Participants underwent a baseline assessment of dynamic retinal vessel analysis (DRVA) and cardiopulmonary exercise testing (CPET) to determine endothelial function and intensity for HIIT. Optical coherences tomography angiography (OCTA) was performed before, immediately and 30 min after one session of HIIT. The primary outcome were changes in ocular vessel parameters and whole body oxygen uptake. Results The UM patient exhibited lower arterial dilation and constriction in the affected eye compared to his healthy eye and both eyes of the healthy control. OCTA revealed heterogeneous patterns of vascular response to HIIT in both participants. The tumor eye showed an increase followed by a significant decrease in vessel density post-exercise, while the healthy control exhibited minor increases. Conclusions The findings of this study highlighted the potential of UM combined with OCTA and DRVA as a model for examine exercise-induced vascular effects within the TME. However, a pre-treated UM as well as detailed image analyses and further research with longitudinal, randomized controlled designs are essential to validate these findings and address methodological limitations. Such investigations could refine integrative cancer treatment.

200 mm optical synthetic aperture imaging over 120 meters distance via macroscopic Fourier ptychography

Fourier ptychography (FP) imaging, drawing on the idea of synthetic aperture, has been demonstrated as a potential approach for remote sub-diffraction-limited imaging. Nevertheless, the farthest imaging distance is still limited to around 10 m, even though there has been a significant improvement in macroscopic FP. The most severe issue in increasing the imaging distance is the field of view (FoV) limitation caused by far-field conditions for diffraction. Here, we propose to modify the Fourier far-field condition for rough reflective objects, aiming to overcome the small FoV limitation by using a divergent beam to illuminate objects. A joint optimization of pupil function and target image is utilized to attain the aberration-free image while estimating the pupil function simultaneously. Benefiting from the optimized reconstruction algorithm, which effectively expands the camera’s effective aperture, we experimentally implement several FP systems suited for imaging distances of 12 m, 65 m, and 120 m with the maximum synthetic aperture of 200 mm. The maximum synthetic aperture is thus improved by more than one order of magnitude of the state-of-the-art works from the furthest distance, with an over fourfold improvement in the resolution compared to a single aperture. Our findings demonstrate significant potential for advancing the field of macroscopic FP, propelling it into a new stage of development.

Picosecond pulsed flat-top beam in a mode-locking all-fiber laser.

Ow7ing to the flat center and steep edge, the flat-top beam is widely used in the fields of micromachining and optical image processing. Here, we propose an efficient scheme to generate a picosecond pulsed flat-top beam in a mode-locking all-fiber laser. After utilizing an orthogonal polarization method for complete incoherence and a high-precision all-fiber optical delay line (ODL) for rigorous time synchronization, the pulsed fundamental mode (LP01) and the pulsed vortex beam (VB) are superimposed to generate a pulsed flat-top beam. The pulsed flat-top beam has a duration of 6.10 ps, with a normalized root mean square (NRMS) variation of 0.049 and a steep degree value of 0.876, indicating an excellent beam quality. In addition, the effect of coherence between the two superimposed beams on the quality of the combined beam has also been investigated. This is the first, to the best of our knowledge, demonstration of a picosecond scale pulsed flat-top beam in the mode-locking all-fiber laser, which may greatly promote its application in laser processing and biomedicine.

The Influence of Cyanine 5.5 and Doxorubicin on Cell Cycle Arrest, Magnetic Resonance, and Near-Infrared Fluorescence Optical Imaging for Fe3O4-Encapsulated PLA-TPGS Nanoparticles.

The combination of magnetic resonance imaging (MRI)/near-infrared (NIR) fluorescence signals and chemotherapy agents has been developed for cancer diagnosis and treatment. In this work, we investigated the impacts of NIR Cyanine 5.5 fluorescence and Doxorubicin on cell cycle arrest, magnetic resonance, and NIR fluorescence optical imaging for Fe3O4-encapsulated nanosystems based on poly(lactide)-tocopheryl polyethylene glycol succinate (PLA-TPGS) copolymer. Although Cyanine 5.5 and Fe3O4 nanoparticles (NPs) are less cytotoxic than Doxorubicin, they present a cytostatic effect, inducing cell cycle arrest at the G2/M phasein human brain adenocarcinoma (CCF-STTG1) cells. For MRI applications, the permeability of the PLA-TPGS copolymer coating layer to water molecules might lengthen the translational diffusion time (τD), causing the high relaxivity ratio (r2/r1) in Fe3O4 bare NPs under an applied magnetic field (7 Tesla). Astonishingly, the chemical structures of Cyanine 5.5 and Doxorubicin significantly contribute to the enhancement of the T2 relaxivities of Fe3O4 NPs through π-π andp-π conjugation. Furthermore, the radiance ratio and signal-to-noise ratio enhancement and a slight blue shift in the optimal excitation and emission wavelengths were recorded. These findings show the potential for in vivo MRI and NIR bioimaging experiments of the nanoparticles.

The Vascular Response After Balloon Angioplasty of Infrapopliteal Intermediate Stenosis Evaluated by Optical Frequency Domain Imaging.

We often experience worsening of stenosis by balloon angioplasty of infrapopliteal (IP) lesion compared with the initial stenosis. However, reports on this phenomenon are limited. The main purpose of this study is to evaluate vascular response after balloon angioplasty of IP artery stenosis. Thirteen patients (15 arteries) who underwent endovascular treatment (EVT) and follow-up angiography with optical frequency domain imaging (OFDI) of intermediate IP stenosis were included. Serial OFDI images at 3 time points (before and after EVT and at follow-up) were analyzed. Diameter and area of external elastic lamina, internal elastic lamina, and lumen were measured, and plaque area and plaque burden (PB) were calculated. PB before EVT was classified into mild, moderate, and severe by 0%-20%, 21%-40%, and 41%-60%, respectively. Analyzed were 229 cross sections. External elastic lamina diameter did not change significantly among three time points (3.8 ± 0.5 [95% confidence interval (CI): 3.7 to 3.9] mm, 3.9 ± 0.4 [95% CI: 3.8 to 4.0] mm, 3.9 ± 0.4 [95% CI: 3.8 to 4.0] mm, p = 0.06). Lumen area increased after EVT but became smaller at follow-up than before EVT (4.5 ± 1.5 [95% CI: 4.3 to 4.7] mm2, 5.3 ± 1.3 [95% CI: 5.1 to 5.5] mm2, 3.7 ± 1.2 [95% CI: 3.5 to 3.9] mm2, p < 0.001). Plaque area became smaller after EVT and larger at follow-up than before EVT (3.0 ± 1.7 [95% CI: 2.8 to 3.2] mm2, 2.4 ± 1.5 [95% CI: 2.2 to 2.6] mm2, 4.0 ± 1.6 [95% CI: 3.8 to 4.2] mm2, p < 0.001). Lumen area was significantly smaller at follow-up than before EVT in mild and moderate PB groups, but it was not different in severe PB group (mild PB group: 5.1 ± 1.5 [95% CI: 4.7 to 5.5] mm2 vs. 4.0 ± 1.3 [95% CI: 3.7 to 4.3] mm2, p < 0.001, moderate PB group: 4.6 ± 1.3 [95% CI: 4.4 to 4.8] mm2 vs. 3.6 ± 1.2 [95% CI: 3.4 to 3.8] mm2, p < 0.001, severe PB group: 3.0 ± 1.4 [95% CI: 2.5 to 3.5] mm2 vs. 3.1 ± 1.0 [95% CI: 2.7 to 3.5] mm2, p = 0.93). Balloon angioplasty of intermediate IP artery stenosis with mild or moderate PB led to smaller lumen area at follow-up than before EVT.

High-density recording reveals sparse clusters (but not columns) for shape and texture encoding in macaque V4.

Macaque area V4 includes neurons that exhibit exquisite selectivity for visual form and surface texture, but their functional organization across laminae is unknown. We used high-density Neuropixels probes in two awake monkeys (one female and one male) to characterize shape and texture tuning of dozens of neurons simultaneously across layers. We found sporadic clusters of neurons that exhibit similar tuning for shape and texture: ∼20% exhibited similar tuning with their neighbors. Importantly, these clusters were confined to a few layers, seldom 'columnar' in structure. This was the case even when neurons were strongly driven, and exhibited robust contrast invariance for shape and texture tuning. We conclude that functional organization in area V4 is not columnar for shape and texture stimulus features and in general organization maybe at a coarser stimulus category scale (e.g. selectivity for stimuli with vs without 3D cues), and a coarser spatial scale (assessed by optical imaging), rather than at a fine scale in terms of similarity in single neuron tuning for specific features. We speculate that this may be a direct consequence of the great diversity of inputs integrated by V4 neurons to build variegated tuning manifolds in a high-dimensional space.Significance Statement In the primary visual cortex of the macaque monkey, studies have demonstrated columnar functional organization, i.e. shared tuning across layers for stimulus orientation, spatial frequency, ocular dominance, etc. In mid and higher level visual form processing stages, where neurons exhibit high-dimensional tuning, functional organization has been harder to evaluate. Here, leveraging the use of the high-density Neuropixels probes to record simultaneously from dozens of neurons across cortical layers, we demonstrate that functional organization is not columnar for shape and texture tuning in area V4, a midlevel stage critical for form processing. Our results contribute to the debate about the functional significance of cortical columns providing support to the idea that they emerge due to one-to-many representational expansion.

Detection of Marine Oil Spill from PlanetScope Images Using CNN and Transformer Models

The contamination of marine ecosystems by oil spills poses a significant threat to the marine environment, necessitating the prompt and effective implementation of measures to mitigate the associated damage. Satellites offer a spatial and temporal advantage over aircraft and unmanned aerial vehicles (UAVs) in oil spill detection due to their wide-area monitoring capabilities. While oil spill detection has traditionally relied on synthetic aperture radar (SAR) images, the combined use of optical satellite sensors alongside SAR can significantly enhance monitoring capabilities, providing improved spatial and temporal coverage. The advent of deep learning methodologies, particularly convolutional neural networks (CNNs) and Transformer models, has generated considerable interest in their potential for oil spill detection. In this study, we conducted a comprehensive and objective comparison to evaluate the suitability of CNN and Transformer models for marine oil spill detection. High-resolution optical satellite images were used to optimize DeepLabV3+, a widely utilized CNN model; Swin-UPerNet, a representative Transformer model; and Mask2Former, which employs a Transformer-based architecture for both encoding and decoding. The results of cross-validation demonstrate a mean Intersection over Union (mIoU) of 0.740, 0.840 and 0.804 for all the models, respectively, indicating their potential for detecting oil spills in the ocean. Additionally, we performed a histogram analysis on the predicted oil spill pixels, which allowed us to classify the types of oil. These findings highlight the considerable promise of the Swin Transformer models for oil spill detection in the context of future marine disaster monitoring.

Circumpapillary OCT-based multi-sector analysis of retinal layer thickness in patients with glaucoma and high myopia

Glaucoma is the leading cause of irreversible blindness worldwide. The diagnosis process for glaucoma involves the measurement of the thickness of retinal layers in order to track its degeneration. The elongated shape of highly myopic eyes can hinder this diagnosis process, since it affects the OCT scanning process, producing deformations that can mimic or mask the degeneration caused by glaucoma. In this work, we present the first comprehensive cross-disease analysis that is focused on the anatomical structures most impacted in glaucoma and high myopia patients, facilitating precise differential diagnosis from those solely afflicted by myopia. To achieve this, a fully automatic approach for the retinal layer segmentation was specifically tailored for the accurate measurement of retinal thickness in both highly myopic and emmetropic eyes. To the best of our knowledge, this is the first approach proposed for the analysis of retinal layers in circumpapillary optical coherence tomography images that takes into account the elongation of the eyes in myopia, thus addressing critical diagnostic needs. The results from this study indicate that the temporal superior (mean difference 11.1μm, p<0.05), nasal inferior (13.1μm, p<0.01) and temporal inferior (13.3μm, p<0.01) sectors of the retinal nerve fibre layer show the most significant reduction in retinal thickness in patients of glaucoma and myopia with regards to patients of myopia.

Brain tissue classification in hyperspectral images using multistage diffusion features and transformer.

Brain surgery is a widely practised and effective treatment for brain tumours, but accurately identifying and classifying tumour boundaries is crucial to maximise resection and avoid neurological complications. This precision in classification is essential for guiding surgical decisions and subsequent treatment planning. Hyperspectral (HS) imaging (HSI) is an emerging multidimensional optical imaging method that captures detailed spectral information across multiple wavelengths, allowing for the identification of nuanced differences in tissue composition, with the potential to enhance intraoperative tissue classification. However, current frameworks often require retraining models for each HSI to extract meaningful features, resulting in long processing times and high computational costs. Additionally, most methods utilise the deep semantic features at the end of the network for classification, ignoring the spatial details contained in the shallow features. To overcome these challenges, we propose a novel approach called MedDiffHSI, which combines diffusion and transformer techniques. Our method involves training an unsupervised learning framework based on the diffusion model to extract high-level and low-level spectral-spatial features from HSI. This approach eliminates the need for retraining of spectral-spatial feature learning model, thereby reducing time complexity. We then extract intermediate multistage features from different timestamps for classification using a pretrained denoising U-Net. To fully explore and exploit the rich contextual semantics and textual information hidden in the extracted diffusion feature, we utilise a spectral-spatial attention module. This module not only learns multistage information about features at different depths, but also extracts and enhances effective information from them. Finally, we employ a supervised transformer-based classifier with weighted majority voting (WMV) to perform the HSI classification. To validate our approach, we conduct comprehensive experiments on in vivo brain database data sets and also extend the analysis to include additional HSI data sets for breast cancer to evaluate the framework performance across different types of tissue. The results demonstrate that our framework outperforms existing approaches by using minimal training samples (5%) while achieving state-of-the-artperformance.

High-resolution optical image reconstruction based on adaptive sparse dictionary

Image spatial resolution reflects the ability of an optical system to capture detailed information about an object. Compared to Low-resolution (LR) images, High-resolution (HR) images contain greater pixel density and textural detail. In the experiments, it is difficult to obtain ideal HR images due to the effects of acquisition equipment and image degradation. To address the problems, this paper proposes a HR optical image reconstruction method based on adaptive sparse dictionary. The experimental show that the area of the modulation transfer function (MTF) curve of the reconstructed image is improved by 16.41%, which represents the increase in the frequency components it contains. Meanwhile the cut-off resolution is improved from 0.2692cy/pix to 0.4018cy/pix. The method in paper achieves good results in both reconstruction efficiency and accuracy. The peak signal-to-noise ratio (PSNR) of the reconstructed image is improved from 20.1650 to 28.0192. The feature similarity (FSIM) and detail retention are above 90%.