Spectroscopic Imaging Techniques Research Articles

Three-dimensional radial echo-planar spectroscopic imaging for hyperpolarized 13C MRSI in vivo.

To demonstrate the feasibility of 3D echo-planar spectroscopic imaging (EPSI) technique with rapid volumetric radial k-space sampling for hyperpolarized (HP) 13C magnetic resonance spectroscopic imaging (MRSI) in vivo. A radial EPSI (rEPSI) was implemented on a 3 T clinical PET/MR system. To enable volumetric coverage, the sinusoidal shaped readout gradients per k-t-spoke were rotated along the three spatial dimensions in a golden-angle like manner. A distance-weighted, density-compensated gridding reconstruction was used, also in cases with undersampling of spokes in k-space. Measurements without and with HP 13C-labeled substances were performed in phantoms and rats using a double-resonant 13C/1H volume resonator with 72 mm inner diameter. Phantom measurements demonstrated the feasibility of the implemented rEPSI sequence, as well as the robustness to undersampling in k-space up to a factor of 5 without advanced reconstruction techniques. Applied to measurements with HP [1-13C]pyruvate in a tumor-bearing rat, we obtained well-resolved MRSI datasets with a large matrix size of 123 voxels covering the whole imaging FOV of (180 mm)3 within 6.3 s, enabling to observe metabolism in dynamic acquisitions. After further optimization, the proposed rEPSI method may be useful in applications of HP 13C-tracers where unknown or varying metabolite resonances are expected, and the acquisition of dynamic, volumetric MRSI datasets with an adequate temporal resolution is a challenge.

The EuAPS Betatron Radiation Source: Status Update and Photon Science Perspectives

The EuPRAXIA EU project is at the forefront of advancing particle accelerator research and the development of photon sources through innovative plasma acceleration approaches. Within this framework, the EuAPS project aims to exploit laser wakefield acceleration to build and operate a betatron radiation source at the INFN Frascati National Laboratory. The EuAPS source will provide femtosecond X-ray pulses in the spectral region between about 1 and 10 keV, unlocking a realm of experimental ultrafast methodologies encompassing diverse imaging and X-ray spectroscopy techniques. This paper presents a description of the EuAPS betatron source, including simulations of the photon beam parameters, outlines the preliminary design of the dedicated photon beamline, and provides an insightful overview of its photon science applications.

Ultrafast dynamics of exciton-polariton fluids at non-zero momenta

In this study, we have explored the ultrafast formation and decay dynamics of exciton-polariton fluids at non-zero momenta, non-resonantly excited by a small-spot femtosecond pump pulse in a ZnO microcavity. Using the femtosecond angle-resolved spectroscopic imaging technique, multidimensional dynamics in both the energy and momentum degrees of freedom have been obtained. Two distinct regions with different decay rate in the energy dimension and various decay-channels in the momentum dimension can be well-resolved. Theoretical simulations based on the generalized Gross–Pitaevskii equation can reach a qualitative agreement with the experimental observations, demonstrating the significance of the initial potential barrier induced by the pump pulse during the decay process. The finding of our study can provide additional insights into the fundamental understanding of exciton-polariton condensates, enabling further advancements for controlling the fluids and practical applications.

Nanometer-precision measurements of geometric fluctuations via momentum-filtered spectroscopy

In this work, we report ultra-sensitive detection of geometric fluctuations of semiconductor nanostructures using momentum-filtered spectroscopy. Our strategy is developed based on angle-resolved photoluminescence/absorption spectroscopic imaging technique. By filtering out signals with non-zero in-plane momentum using a confocal pinhole, ultra-sensitive detection of tiny geometric fluctuations with nanometer precision was made possible. In this way, we could optically detect geometric fluctuations of semiconductor nanostructures in real-time with a spatial resolution as high as ∼0.2 nm. Moreover, this technique is widely applicable to nanostructures where optical resonance can be formed.

Assessment of Hypoxia in Breast Cancer: Emerging Functional MR Imaging and Spectroscopy Techniques and Clinical Applications.

Breast cancer is one of the most prevalent forms of cancer affecting women worldwide. Hypoxia, a condition characterized by insufficient oxygen supply in tumor tissues, is closely associated with tumor aggressiveness, resistance to therapy, and poor clinical outcomes. Accurate assessment of tumor hypoxia can guide treatment decisions, predict therapy response, and contribute to the development of targeted therapeutic interventions. Over the years, functional magnetic resonance imaging (fMRI) and magnetic resonance spectroscopy (MRS) techniques have emerged as promising noninvasive imaging options for evaluating hypoxia in cancer. Such techniques include blood oxygen level-dependent (BOLD) MRI, oxygen-enhanced MRI (OE) MRI, chemical exchange saturation transfer (CEST) MRI, and proton MRS (1H-MRS). These may help overcome the limitations of the routinely used dynamic contrast-enhanced (DCE) MRI and diffusion-weighted imaging (DWI) techniques, contributing to better diagnosis and understanding of the biological features of breast cancer. This review aims to provide a comprehensive overview of the emerging functional MRI and MRS techniques for assessing hypoxia in breast cancer, along with their evolving clinical applications. The integration of these techniques in clinical practice holds promising implications for breast cancer management. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 1.

Variation of the electron flux spectrum along a solar flare loop as inferred from STIX hard X-ray observations

Context. Regularized imaging spectroscopy was introduced for the construction of electron flux images at different energies from count visibilities recorded by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). In this work we seek to extend this approach to data from the Spectrometer/Telescope for Imaging X-rays (STIX) on board the Solar Orbiter mission. Aims. Our aims are to demonstrate the feasibility of regularized imaging spectroscopy as a method for analysis of STIX data, and also to show how such an analysis can lead to insights into the physical processes affecting the nonthermal electrons responsible for the hard X-ray emission observed by STIX. Methods. STIX records imaging data in an intrinsically different manner from RHESSI. Rather than sweeping the angular frequency plane in a set of concentric circles (one circle per detector), STIX uses 30 collimators, each corresponding to a specific angular frequency. For this work, we derived an appropriate modification to the previous computational approach for the analysis of the visibilities observed by STIX. This approach also allows for the observed count data to be placed into nonuniformly spaced energy bins. Results. We show that the regularized imaging spectroscopy approach is not only feasible for an analysis of the visibilities observed by STIX, but also more reliable. The application of the regularized imaging spectroscopy technique to several well-observed flares reveals details of the variation of the electron flux spectrum throughout the flare sources. Conclusions. We conclude that the visibility-based regularized imaging spectroscopy approach is well suited for the analysis of STIX data. We also used STIX electron flux spectral images to track, for the first time, the behavior of the accelerated electrons during their path from the acceleration site in the solar corona toward the chromosphere.

Simulation and quantitative analysis of Raman spectra in chemical processes with autoencoders

Raman spectroscopy represents an advanced process analytical technology to monitor and control chemical and biochemical processes. This study presents an autoencoder-based methodology that simulates Raman spectra from process variables and predicts the concentrations of different chemicals. The methodology accurately predicts concentrations from the spectra, even considering the temperature influences, and can work as an anomaly detector in process monitoring. The proposed methodology has significant implications for the optimization of industrial processes, improving process efficiency, reducing waste, and minimizing costs. It can also be extended to other industrial processes and imaging spectroscopy techniques, making it a valuable tool for process monitoring. This study highlights the effectiveness of autoencoders in simulating spectra and quantitative analysis, contributing significantly to the field of process monitoring. It has the potential to revolutionize industrial process monitoring and optimization, leading to substantial improvements in productivity and sustainability.

First measurements with a Coherence Imaging Charge Exchange Recombination Spectroscopy (CICERS) diagnostic at Wendelstein 7-X

In this work, the Coherence Imaging Spectroscopy technique is exploited for active charge exchange radiation measurements to infer high spatial resolution 2D ion temperature ( Ti ) maps in the core region of Wendelstein 7-X plasmas. A synthetic model of the diagnostic is developed and used for the optimization of the hardware components for the expected ion temperatures ( Ti∼2 keV) prioritizing Ti measurements while also considering the ion velocity flow resolution. The experimental set-up is shown and the diagnostic calibration procedure for Ti measurements is introduced. A combination of both simulations and experimental calibrations enable high fidelity system group delay ( ∂ϕ∂λ ) characterization in the whole visible spectral range. Finally, the signal processing techniques applied to the diagnostic signal are introduced and first measurements of 2D Ti maps are presented and validated against standard Charge eXchange Recombination Spectroscopy Ti profiles, finding excellent agreement.

New insights on collagen structural organization and spatial distribution around dental implants: a comparison between machined and laser-treated surfaces

BackgroundOne of the main factors for the osseointegration of dental implants is the development of an adequate soft tissue barrier, mainly composed by collagen, which protects the implant from bacterial development. The structural features of the peri-implant collagen are influenced by the implant components and, in particular, by the type of the surface. In the clinical practice, healing abutments are characterized by smooth surfaces, named machined. Recently, a new laser technique, Synthegra, has been developed to obtain a topography-controlled surface with micrometric regular pores that seems reducing the risk of peri-implantitis. Based on this background, this study aims investigating the structural organization and spatial distribution of collagen surrounding healing abutments characterized by laser-treated and machined surfaces.MethodsGingiva portions surrounding custom-made healing abutments (HA), characterized by alternated laser-treated and machined surfaces, were collected and analyzed by combining Fourier Transform InfraRed Imaging (FTIRI) spectroscopy, a non-invasive and high-resolution bidimensional analytical technique, with histological and multivariate analyses.ResultsMasson’s trichrome staining, specific for collagen, highlighted a massive presence of collagen in all the analyzed samples, evidencing a surface-related spatial distribution. The nature of collagen, investigated by the FTIRI spectroscopy, appeared more abundant close to the laser-treated surface, with a perpendicular disposition of the bundles respect to the HA; conversely, a parallel distribution was observed around the machined surface. A different secondary structure was also found, with a higher amount of triple helices and a lower quantity of random coils in collagen close to the laser treated surfaces.ConclusionsFTIRI spectroscopy demonstrates that the use of a laser treated transmucosal surface can improve the morphological organization of the peri-implant collagen, which presents a distribution more similar to that of natural teeth.Trial registration: This trial is registered with ClinicalTrials.gov Identifier: (Registration Number: NCT05754970). Registered 06/03/2023, retrospectively registered, https://clinicaltrials.gov/show/NCT05754970.

A Pre-Trial Study to Identify Species of Origin in Halloumi Cheese Utilising Chemometrics with Near-Infrared and Hyperspectral Imaging Technologies

Halloumi cheese has recently gained a Protected Designation of Origin (PDO) indicator, which is related to the place (Cyprus) in which halloumi cheese is made. The PDO label is linked with several requirements, e.g., milk species, quantities, etc.; thus, it is important to study this product regarding authenticity. The utility of using two spectroscopic techniques, hyperspectral imaging (HSI) (400–1000 nm) and conventional near-infrared spectroscopy (NIR) (800–2500 nm) were assessed for the discrimination of 17 Cypriot halloumi cheese types, which could be categorized as of cow or goat–sheep origin. The aim of this study was to obtain spectral information for halloumi cheese using other promising infrared and imaging spectroscopic techniques as a comparison to a previously acquired mid-infrared (MIR) spectroscopy dataset. NIR and HSI are both fast and easy techniques in application, both of which provide significant information in food analysis. Chemometric analysis was crucial for interpreting the spectroscopic data by applying the unsupervised methods: principal component analysis (PCA) and hierarchical cluster analysis (HCA). The HSI model was found to be based intuitively on the appearance of cheese samples after freeze-drying (e.g., color; yellow/white, and texture; oily/dry), while the NIR grouping of samples was determined to be based on composition, mainly fat, protein and lactose content of the cheese samples. The HSI model returned distinct clusters of the two halloumi cheese types, cow and goat–sheep origin, with one outlier (16/17 accuracy; 94%), while the NIR model proved less accurate (13/17; 76%).

Characterisation of HEXITECMHz - A 1 MHz continuous frame rate spectroscopic X-ray imaging detector system

Spectroscopic X-ray imaging techniques including Compton X-ray Imaging, X-ray Fluorescence Imaging and Hyperspectral X-ray Tomography require energy-resolving detectors capable of operating at high incident X-ray fluxes to make time resolved measurements. HEXITECMHz, operates at a continuous 1 MHz frame rate and can make fully spectroscopic measurements at >106 ph s−1 mm−2. This is enabled by an integrating Front End, in-pixel digitisation and high-speed serialisers. A 300 μm thick p-type Si HEXITECMHz detector was characterised on the B16 Test Beamline at the Diamond Light Source and are the first measurements taken at a 1 MHz frame rate. At 10 keV and 15 keV) the device displayed average FWHM of 656 eV and 682 eV respectively, with minimal changes in spectroscopic performance over ∼8 h. Analysis of charge-sharing events show low charge loss and a linear energy-signal response. Higher-flux measurements illustrated the capability of the ASIC to operate as a photon-counting device.

Spectroscopy Imaging Techniques as In Vivo Analytical Tools to Detect Plant Traits

The efficiency of hyper- and multispectral imaging (HSI and MSI) has gained considerable attention in research on plant phenotyping. This is due to their ease of use while being considered a nondestructive technology. Unlike current point-scanned spectroscopy, both HSI and MSI extract spatial and spectral information while covering a wide range of a plant body. Moreover, it is necessary to equip the extracted information with multivariate calibration techniques, followed by model evaluation. To date, the application of HSI and MSI for monitoring plant growth under a controlled environment is emerging and showing a good trend. Our systematic literature review discusses spectroscopy imaging techniques and their chemometric approaches as a sustainable sensor technology to detect plant traits. In conclusion, we also explore the possibility of carrying out HSI and MSI during plant trait analysis.

Robotic Exploration of Europa's Subsurface with Autonomous Underwater Vehicle (AUV): A Comprehensive Mission Concept and Design

Next-generation space explorers are keen to identify potential bio signatures on other planets and extraterrestrial bodies. So, we have explored Moon and Mars with scientific landers and rovers which transmitted lots of data for exploration beyond earth's orbit. In this scenario, Europa a moon of Jupiter holds a potential site for biological exploration and detection of bio signatures. In addition, spacecraft have identified that the moon is ejecting water vapor into the surface wherein it could hold all the possible elements to support life under the surface. Going forward, orbiters and landers might produce inaccurate results with spectroscopic analysis and imaging techniques, and it is significant to deploy bots or penetrators into the surface for deep investigation and analysis. Therefore, in this paper, we intend to develop and deploy an AUV (Autonomous Underwater Vehicle) for detecting biological signs and to do numerous biological investigations. Studying Europa's water and its interactions with the moon's icy crust provides valuable insights into the potential habitability of icy worlds and the possibilities for life beyond Earth and that exclusively is the work of our AUV. This project can also help further researches on this moon of Jupiter. The AUV will be deployed into the surface via a lander which will act as a ground command for further operation and data transmission. Further, we have planned to develop a 3D model and simulate its operation in upcoming years. Finally, the objective of this mission might provide useful insights for a future manned exploration missions to Europa considering the complete challenges.

Interdiffusion measurements in thermally controlled microchannel using infrared spectroscopic imaging

In many applications, knowledge of the mass diffusivity coefficient is mandatory to optimize the design and operating conditions of microfluidic devices and chemical reactions. The literature reports few values due to limited techniques, and the impact of the fluid temperature is rarely taken into account when the diffusivity is measured. In this study, we present an imaging method to investigate and quantify the interdiffusion of two fluids in a microchannel under controlled temperatures. The experimental setup combines a thermally controlled microfluidic chip and a microscale infrared (IR) spectroscopy imaging technique. The mass diffusivity of formic acid (HCOOH) in sulfuric acid (H2SO4) was measured from room temperature to 50°C to demonstrate the performance of the setup. This work offers a rapid tool and a methodology for accurate contactless interdiffusion measurements in thermally controlled T-shape reactors applicable a large set of chemicals.

Early detection of the Mediterranean Fruit Fly, Ceratitis capitata (Wied.) in oranges using different aspects of remote sensing applications

Mediterranean Fruit Fly, Ceratitis capitata (Diptera: Tephritidae) is regarded as an important pest of orange (Citrus). Early detection of pest infestations enables theoptimal application of preventative and control measures. This study was carried out under laboratory conditions, in order to predict and monitor orange pest infestations. Consequently, the scope was to find a remote sensing application that can help in the prediction of Mediterranean Fruit Fly infestation in oranges with the least loss in production. Spectroscopic and thermal imaging techniques were investigated, as effective tools in determination of pest infestation and damage in orange fruits. According to the findings, the optimum spectral zones that can be used to discriminate and differentiate between healthy (non-infected) orange fruit and infected ones were red and near infrared bands. Six vegetation indices were calculated to analyze the Field Spectral measurements. By calculating the NPCI (Normalized Pigment Chlorophyll Index), it was found that NPCI values for infected orange fruits were higher in comparison to healthy ones. Thermal imaging showed that the infected orange fruit temperatures were on average 0.8 °C higher than that of healthy fruits. As the maximum temperature differential (MTD) between healthy and infected fruits were 23.7–24.5 °C, respectively. These spectral reflectance curves were useful for researchers working on Site-specific crop management, as they can use remote sensing to detect individual fruit infections. Also, this technique should be used as a powerful and non-destructive method for assistance in agriculture.

Covalently modified Kevlar fabric incorporating graphene oxide with enhanced antibacterial properties and preserved strength.

This work describes a multi-step modification process for the covalent transformation of Kevlar fabric en route the incorporation of graphene oxide (GO) nanosheets. Spectroscopic, thermal and microscopy imgaing techniques have been employed to follow step-by-step the modification of Kevlar and the formation of the corresponding Kevlar-GO hybrid fabric. The level of Kevlar's functionalization can be controled with the nitration time, the first reactionin the multi-sequence organic transformations, for obtaining the hybrid fabricwith a content of GO up to 30%. Most importantly, the covalent post-modification of Kevlar does not occur in the expense of the other otherwise excellent mechanical properties of the fabric. Under optimal conditions, theKevlar-GO hybrid fabric shows a 20% enhancement of the ultimate strengh. Notably, when the Kevlar-GO hybrid fabric exposed to cyanobacterialSynechococcusthe bacteria growth was fully inhibited. Overall, the covalently modified fabric demonstrated significant antibacterial behavior, excellent strength and stability under common processes. Due to its simplicity, the methodology presented in this work not only promises to result in a standard procedure to functionalize themerunits of Kevlar witha variety of chemicals and nanomaterials but it can be also extended for the modification and hybridization of other fabrics.

NEIM-11 DEUTERIUM METABOLIC IMAGING (DMI) DETECTS A LARGER WARBURG EFFECT IN HIGH-GRADE BRAIN TUMORS AND IN IDH WILD TYPE GLIOMAS

Abstract BACKGROUND The Warburg Effect (WE) is a metabolic change in which tumors favor glycolysis over oxidative phosphorylation and has been linked to cancer aggressiveness. Mutations in the isocitrate dehydrogenase (IDH) genes in gliomas are associated with improved outcomes. We deployed a magnetic resonance (MR) spectroscopic imaging technique coined Deuterium Metabolic Imaging (DMI) to measure the WE in multiple brain tumor types. METHODS Twenty-one patients underwent DMI, acquired on a Bruker 4T MR scanner after oral administration of 0.75g/kg of deuterated glucose. The WE was defined as the ratio of deuterated lactate, representing glycolysis, over deuterated glutamate and glutamine, representing oxidative phosphorylation. We devised an interval scale from 0 to 2 for the WE RESULTS The Wilcoxon rank sum test was performed to detect differences between groups. RESULTS The WE measurements for the largest groups, by diagnosis, showed: glioblastoma (n=9, mean=1.67); astrocytoma, IDH-mutant, WHO grade 3 (n=2, mean=0.25); oligodendroglioma, WHO grade 3 (n=3, mean=0.5); low grade glioma, IDH-mutant (n=2, mean=0); and meningioma, WHO grade 2 (n=2, mean=0). The WE for high-grade tumors (n=15, mean=1.27) was significantly different from the WE for low-grade tumors (n=5, mean=0), with a p=0.010. The WE for IDH wild type gliomas (n=9, mean=1.67) was significantly different from the WE for IDH-mutant gliomas (n=9, mean=0.44), with a p=0.007. Analysis is ongoing. CONCLUSIONS DMI successfully and non-invasively detects the WE in many types of brain tumors. The WE was larger in high-grade tumors as compared to low-grade tumors, and the WE was larger in IDH wild type gliomas as compared to IDH-mutant gliomas. If validated with future studies, our results suggest that DMI is a useful tool to measure differences in the metabolism of brain tumors with different clinical behaviors.

Monitoring of banana’s optical properties by laser light backscattering imaging technique during drying

Banana drying is an important process that used to extend the shelf life and increase the marketability of the dried banana. However, this process can lead to changes in weight loss, firmness, and color, which may influence consumer acceptance. As a result, it is crucial to monitor these changes to maintain the desired quality. Therefore, the aim of this study was to assess the quality of sliced bananas during the drying process by simultaneously monitoring their optical and physical properties using laser light backscatter imaging, near-infrared spectroscopy, and electrical impedance spectroscopy techniques. Banana sliced were prepared with 10 mm thickness and immersed into 4% ascorbic acid solution and water as treated and control samples dried at 50 °C for 6 h. The parameters measured were weight loss, color, firmness, NIR absorbance in the range from 740 to 1700 nm and electrical impedance in the frequency range from 30 kHz to 1 MHz. Absorption, reduced scattering and diffusion coefficients, penetration depth and full width at half maximum (FWHM) were computed on the LLBI signal at wavelengths of 532, 635, 780, 808, 850 and 1064 nm. The results showed that both the drying time and the ascorbic acid treatment and their interaction affected the measured values. The strong NIR absorption spectrum changes observed at wavelengths of 1064 and 1416 nm. The least squares partial regression model (PLSR) was performed with high accuracy for weight loss (%) and relaxation time (ms) at a coefficient of determination (R2) of 0.940 and 0.945 with a mean square error (RMSE) of 3.748 and 0.001, respectively. The electrical impedance spectral changes were found in the frequency range from 60 Hz to 1 MHz. The most sensitive laser wave lengths to evaluate optical properties were 532, 635, 780 and 1064 nm. Therefore, laser backscatter imaging together with NIR spectroscopy and impedance spectroscopy is a promising technique to assess the quality of sliced bananas during the drying process.Graphical abstract

Identification of traditional black Persian inks by spectroscopic and spectral imaging techniques: Presenting a flowchart method

The aim of this study is to identify different types of traditional Persian inks using molecular spectroscopy and spectral imaging methods. This study focused on six types of black inks - carbon, iron-gall, carbo-gall-vitriol, carbo-gall-alum, peacock, and starch, which were prepared using traditional Persian recipes. After preparation, the inks were subsequently analyzed with the aid of Raman spectroscopy, FTIR spectroscopy, micro-spectrophotometer, FORS, technical imaging, hyperspectral imaging and SEM. The findings revealed that Raman spectroscopy can differentiate between carbon-based and iron-gall-based inks. Additionally, SEM-BSE imaging and EDS, which provides information about the presence of vitriol and alum in some of the inks, can assist Raman spectroscopy results in identifying these inks. Spectral imaging helps classify the inks as either carbon-based or iron-gall-based. FTIR spectroscopy, on the other hand, shows more reliable outcomes in identifying different types of inks, albeit it cannot effectively differentiate between iron-gall and carbo-gall-vitriol inks. However, their identification is still possible because these two inks have distinct reflective spectra. As a result, this research demonstrates that spectroscopic and spectral imaging techniques, coupled with a multi-analytical approach, are effective in identifying types of traditional Persian black inks.

Laser spectroscopy imaging technique coupled with nanomaterials for cancer diagnosis: A review

Laser spectroscopic imaging techniques have received tremendous attention in the field of cancer diagnosis due to their high sensitivity, high temporal resolution, and short acquisition time. However, the limited tissue penetration of the laser is still a challenge for the in vivo diagnosis of deep-seated lesions. Nanomaterials have been universally integrated with spectroscopic imaging techniques for deeper cancer diagnosis in vivo. The components, morphology, and sizes of nanomaterials are delicately designed, which could realize cancer diagnosis in vivo or in situ. Considering the enhanced signal emitting from the nanomaterials, we emphasized their combination with spectroscopic imaging techniques for cancer diagnosis, like the surface-enhanced Raman scattering (SERS), photoacoustic, fluorescence, and laser-induced breakdown spectroscopy (LIBS). Applications of the above spectroscopic techniques offer new prospects for cancer diagnosis.