Micron-scale Imaging Research Articles

Virtual Hall sensor triggered multi-MHz endoscopic OCT imaging for stable real-time visualization.

Circumferential scanning in endoscopic imaging is crucial across various disciplines, and optical coherence tomography (OCT) is often the preferred choice due to its high-speed, high-resolution, and micron-scale imaging capabilities. Moreover, real-time and high-speed 3D endoscopy is a pivotal technology for medical screening and precise surgical guidance, among other applications. However, challenges such as image jitter and non-uniform rotational distortion (NURD) are persistent obstacles that hinder real-time visualization during high-speed OCT procedures. To address this issue, we developed an innovative, low-cost endoscope that employs a brushless DC motor for scanning, and a sensorless technique for triggering and synchronizing OCT imaging with the scanning motor. This sensorless approach uses the motor's electrical feedback (back electromotive force, BEMF) as a virtual Hall sensor to initiate OCT image acquisition and synchronize it with a Fourier Domain Mode-Locked (FDML)-based Megahertz OCT system. Notably, the implementation of BEMF-triggered OCT has led to a substantial reduction in image jitter and NURD (<4 mrad), thereby opening up a new window for real-time visualization capabilities. This approach suggests potential benefits across various applications, aiming to provide a more accurate, deployable, and cost-effective solution. Subsequent studies can explore the adaptability of this system to specific clinical scenarios and its performance under practical endoscopic conditions.

Automated quality evaluation for laser cutting in lithium metal battery production using an instance segmentation convolutional neural network

Separating lithium metal foil into individual anodes is a critical process step in all-solid-state battery production. With the use of nanosecond-pulsed laser cutting, a characteristic quality-decisive cut edge geometry is formed depending on the chosen parameter set. This cut edge can be characterized by micrometer-scale imaging techniques such as confocal laser scanning microscopy. Currently, experimental determination of suitable process parameters is time-consuming and biased by the human measurement approach, while no methods for automated quality assurance are known. This study presents a deep-learning computer vision approach for geometry characterization of lithium foil laser cut edges. The convolutional neural network architecture Mask R-CNN was implemented and applied for categorizing confocal laser scanning microscopy images showing defective and successful cuts, achieving a classification precision of more than 95%. The algorithm was trained for automatic pixel-wise segmentation of the quality-relevant melt superelevation along the cut edge, reaching segmentation accuracies of up to 88%. Influence of the training data set size on the classification and segmentation accuracies was assessed confirming the algorithm’s industrial application potential due to the low number of 246 or fewer original images required. The segmentation masks were combined with topography data of cut edges to obtain quantitative metrics for the quality evaluation of lithium metal electrodes. The presented computer vision pipeline enables the integration of an automated image evaluation for quality inspection of lithium foil laser cutting, promoting industrial production of all-solid-state batteries with lithium metal anode.

Minimally Invasive Polarization Sensitive Optical Coherence Tomography (PS-OCT) for assessing Pre-OA, a pilot study on technical feasibility

ObjectiveEfforts to develop chondroprotective approaches to halt osteoarthritis (OA) progression have recently increased. Current imaging techniques are critical in managing advanced OA, but greater resolution is needed to identify reversible stages (pre-OA). Optical coherence tomography (OCT) is a micron scale imaging technology widely used in ophthalmology, cardiology, and neurology. We previously demonstrated that polarization sensitive OCT (PS-OCT) can identify pre-OA in vitro, in animals, and in open surgical fields. This feasibility study examines performing intraarticular PS-OCT using a flexible endocatheter introduced through a stiff 18-gauge spinal needle. Results are critical for designing larger clinical trials examining minimally invasive PS-OCT's ability to identify pre-OA. DesignFifteen patients undergoing arthroscopic partial medial meniscectomy were selected to confirm their risk for rapid progression to OA. Magnetic resonance imaging (MRI) was obtained at time 0 and at 2.5 years to determine if significant OA developed over this short period and for correlation with time zero PS-OCT results. ResultsOver half of the patients developed frank OA by 2.65 ​± ​0.28 years. All cartilage surfaces were successfully imaged by PS-OCT, but endocatheter redesign is needed. Normal to severely abnormal areas by PS-OCT (all normal by MRI) were successfully identified. PS-OCT assessments were promising for predicting OA progression (p ​< ​0.008). However, the study's low power prevented definite conclusions regarding predictive value. ConclusionsThis pilot study produced at least two outcomes critical for future larger trial designs: medial meniscectomy patients are well-suited for studying PS-OCT's ability to predict future OA and substantial endocatheter redesign is needed.

High-Speed Wide-Field Imaging of Microcircuitry Using Nitrogen Vacancies in Diamond

The ability to measure the passage of electrical current with high spatial and temporal resolution is vital for applications ranging from inspection of microscopic electronic circuits to biosensing. The ability to image such signals passively and remotely is of great importance, in order to measure without invasive disruption of the system under study or the signal itself. A recent approach to achieving this utilizes point defects in solid-state materials; in particular, nitrogen-vacancy centers in diamond. Acting as a high-density array of independent sensors, addressable opto-electronically and highly sensitive to factors including temperature and magnetic field, these are ideally suited to microscopic wide-field imaging. In this work, we demonstrate simultaneous spatially and temporally resolved recovery signals from a microscopic lithographically patterned circuit. Through application of a lock-in amplifier camera, we demonstrate micrometer-scale imaging resolution with a millimeter-scale field of view with simultaneous spatially resolved submillisecond (up to 3500 frames ${\mathrm{s}}^{\ensuremath{-}1}$) recovery of dc to kilohertz alternating and broadband pulsed-current electrical signals, without aliasing or undersampling. We demonstrate as examples of our method the recovery of synthetic signals replicating digital pulses in integrated circuits and signals that would be observed in a biological neuronal network in the brain.

Passive Low-Energy Nuclear-Recoil Detection with Color Centers

Crystal-damage events such as tracks and point defects have been used to record and detect radiation for a long time and recently they have been proposed as a means for dark-matter detection. Color centers can be read out optically and we propose a scheme based on selective plane illumination microscopy for micrometer-scale imaging of large volumes corresponding to kilogram mass detectors. This class of detectors would be passive and would operate at room temperature and we call this the passive low-energy optical color-center nuclear-recoil (PALEOCCENE) detection method. We apply these concepts to the detection of reactor neutrinos using coherent elastic neutrino nucleus scattering (CE$\ensuremath{\nu}$NS). Crystal-damage formation energies are intrinsically on the order of 25 eV, resulting in similarly low nuclear-recoil thresholds. This would enable the observation of reactor-neutrino CE$\ensuremath{\nu}$NS with detectors as small as 10 g. Additionally, a competitive search for spin-dependent dark-matter scattering down to a dark-matter mass of $0.3$ GeV could be possible. Passive crystal detectors might also be attractive for nuclear-nonproliferation safeguards if used to monitor reactor power and to put limits on plutonium production. The passive nature and small footprint of the proposed detectors implies that these might fit well within accepted reactor-safeguards operations.

Endomicroscopy of the human cochlea using a micro-optical coherence tomography catheter

Sensorineural hearing loss (SNHL) is one of the most profound public health concerns of the modern era, affecting 466 million people today, and projected to affect 900 million by the year 2050. Advances in both diagnostics and therapeutics for SNHL have been impeded by the human cochlea’s inaccessibility for in vivo imaging, resulting from its extremely small size, convoluted coiled configuration, fragility, and deep encasement in dense bone. Here, we develop and demonstrate the ability of a sub-millimeter-diameter, flexible endoscopic probe interfaced with a micro-optical coherence tomography (μOCT) imaging system to enable micron-scale imaging of the inner ear’s sensory epithelium in cadaveric human inner ears.

Spectral Imaging and Computer Vision for High-Throughput Defect Detection and Root-Cause Analysis of Silicon Nanopillar Arrays

Abstract Far-field spectral imaging, coupled with computer vision methods, is demonstrated as an effective inspection method for detection, classification, and root-cause analysis of manufacturing defects in large area Si nanopillar arrays. Si nanopillar arrays exhibit a variety of nanophotonic effects, causing them to produce colors and spectral signatures which are highly sensitive to defects, on both the macro- and nanoscales, which can be detected in far-field imaging. Compared with traditional nanometrology approaches like scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical scatterometry, spectral imaging offers much higher throughput due to its large field of view (FOV), micrometer-scale imaging resolution, sensitivity to nm-scale feature geometric variations, and ability to be performed in-line and nondestructively. Thus, spectral imaging is an excellent choice for high-speed defect detection/classification in Si nanopillar arrays and potentially other types of large-area nanostructure arrays (LNAs) fabricated on Si wafers, glass sheets, and roll-to-roll webs. The origins of different types of nano-imprint patterning defects—including particle voids, etch delay, and nonfilling—and the unique ways in which they manifest as optical changes in the completed nanostructure arrays are discussed. With this understanding in mind, computer vision methods are applied to spectral image data to detect and classify various defects in a sample containing wine glass-shaped Si resonator arrays.

Estimating Fluid Saturations from Capillary Pressure and Relative Permeability Simulations Using Digital Rock

Direct numerical simulations of fluid flow on three-dimensional pore-scale microstructures derived from images promise more, cheaper, and faster, special core analysis for estimating volumetric and transport properties of rocks. However, the micron-scale X-ray computer tomography images generated by the present imaging technology are limited in resolution, and thus, a significant portion of rock pore volume can remain unresolved. The missing pore volume is not accessible to direct numerical simulations which limits applicability of digital rock physics to infer true residual saturation of reservoir fluids. To derive meaningful results from direct simulations, at minimum, raw fluid saturation inferred from simulations on micron-scale images must be corrected for the missing pore volume. We use concepts of capillary physics in rocks to quantify the impact of image resolution on image-derived fluid saturation and develop novel transforms that compensate for this effect on estimates of fluid saturation from multiphase simulations without the need for higher-resolution imaging. We find that image resolution constraints provide quality indicators when comparing digital rock-derived fluid saturations (e.g., connate water saturation) with those measured in a laboratory.

Estimating electrical cementation and saturation exponents using digital rock physics

Accurate quantitative determination of hydrocarbon saturation is important for informing decisions on hydrocarbon reservoir development and management. Petrophysical saturation models, like Archie, Waxman-Smits and other electrical conductivity models, are used to calculate the hydrocarbon saturation from resistivity logs. As these models contain empirical parameters, their accuracy typically depends on calibration against laboratory measurements using core samples. Alternatively, X-ray computer microtomography (Micro-CT) based Digital Rock technology promises a cheaper and faster method for calibrating these empirical parameters, but only if known limitations are addressed. Micron-scale X-ray computer tomography images generated by current imaging technology are limited in resolution; thus, a significant portion of rock pore volume can remain unresolved. This missing pore volume is not accessible to numerical solvers/simulators that simulate multiphase flow and electrical conductivity, which reduces the accuracy of the simulated results and limits applicability of Digital Rock technology. To get meaningful results from direct simulations, at minimum, image-derived exponents inferred from micron-scale images must be corrected for the missing pore volume. To derive the corrected Archie exponents, we develop novel transforms that compensate for the limited image resolution. The exponents predicted by our method agree with those obtained experimentally for reservoir rocks within ± 0.1.

Combining surface-sensitive microscopies for analysis of biological tissues after neural device implantation.

In order to address the complexity of chemical analysis of biological systems, time-of-flight secondary ion mass spectrometry (ToF-SIMS), x-ray photoelectron spectroscopy (XPS), and x-ray photoemission electron microscopy (XPEEM) were used for combined surface imaging of a biological tissue formed around a surface neural device after implantation on a nonhuman primate brain. Results show patterns on biological tissue based on extracellular matrix (ECM) and phospholipid membrane (PM) molecular fragments, which were contrasted through principal component analysis of ToF-SIMS negative spectrum. This chemical differentiation may indicate severe inflammation on tissue with an early case of necrosis. Quantification of the elemental composition and the chemical bonding states on both ECM-rich and PM-rich features was possible through XPS analysis from survey and high-resolution spectra, respectively. Variable amounts of carbon (68%-80.5%), nitrogen (10%-2.4%), and oxygen (20.8%-16.5%) were detected on the surface of the biological tissue. Chlorine, phosphorous sodium, and sulfur were also identified in lower extends. Besides that, analysis of the C 1s high-resolution spectra for the same two regions (ECM and PM ones) showed that a compromise between C-C (41.8 at. %) and C-N/C-O (35.6 at. %) amounts may indicate a strong presence of amino acids and proteoglycans on the ECM fragment-rich region, while the great amount of C-C (70.1 at. %) on the PM fragment-rich region is attributed to the large chains of fatty acids connected to phospholipid molecules. The micrometer-scale imaging of these chemical states on tissue was accomplished through XPEEM analysis. The C-C presence was found uniformly distributed across the entire analyzed area, while C-N/C-O and C=O were in two distinct regions. The combination of ToF-SIMS, XPS, and XPEEM is shown here as a powerful, noninvasive approach to map out elemental and chemical properties of biological tissues, i.e., identification of chemically distinct regions, followed by quantification of the surface chemical composition in each distinct region.

Optical coherence refraction tomography.

Optical coherence tomography (OCT) is a cross-sectional, micron-scale imaging modality with widespread clinical application. Typical OCT systems sacrifice lateral resolution to achieve long depths of focus for bulk tissue imaging, and hence tend to have better axial than lateral resolution. Such anisotropic resolution can obscure fine ultrastructural features. Furthermore, conventional OCT suffers from refraction-induced image distortions. Here, we introduce optical coherence refraction tomography (OCRT), which extends the superior axial resolution to the lateral dimension, synthesising undistorted cross-sectional image reconstructions from multiple conventional images acquired with angular diversity. In correcting refraction-induced distortions to register the OCT images, OCRT also achieves spatially resolved refractive index imaging. We demonstrate >3-fold improvement in lateral resolution as well as speckle reduction in imaging tissue ultrastructure, consistent with histology. With further optimisation in optical designs to incorporate angular diversity into clinical instruments, OCRT could be widely applied as an enhancement over conventional OCT.

Phase-sensitive imaging of microwave currents in superconductive circuits

We propose an improved measuring technique for microwave currents in superconductive circuits, demonstrate it experimentally, and validate the experimental data with numerical simulations. Contemporary superconductive electronics widely uses planar circuits with micrometer-scale elements for a variety of applications. With the rise of complexity of a circuit and increase in the number of its components, a simple impedance measurement is often not efficient for the diagnosis of problems, nor for clarifying the physics underlying the circuit response. The established Laser Scanning Microscopy (LSM) technique generates micrometer-scale images of the amplitude of the microwave currents in a planar superconductive circuit, but not the phase of the oscillating currents. Here, we present a more powerful type of LSM imaging containing signal phase information. We employ a fast-optical modulator in order to synchronize the phase of the laser intensity oscillation with the phase of the probing microwave signal. The loss induced in a laser illuminated area strongly depends on the phase difference between the RF probing signal and the laser beam modulation. As a proof of concept, we present the phase-sensitive LSM measurements of the inner mode currents in a planar superconductive resonator and confirm the data with numerical simulation of the resonator's electrodynamics.

Estimating Pore Volume of Rocks from Pore-Scale Imaging

Significant progress has been made in the field of pore-scale imaging in the last decade which is revolutionizing various scientific disciplines, including biology, material science, and food engineering. Pore-scale imaging holds considerable potential for estimating volumetric and hydromechanical properties of rocks for a variety of geoscience applications. However, the micron-scale images, generated by the present imaging technology, are limited in resolution and thus a significant portion of rock pore volume can remain unresolved. We use the established concepts of capillary physics in rocks to infer rock porosity that sits in pores that are smaller than the image voxel without the need for higher resolution imaging that is only possible at the expense of image field of view or physical laboratory measurement. This allows us to estimate porosity of reservoir rocks using X-ray computer tomography even when a significant portion of pore volume is below image resolution. We find that the porosity inferred by our method matches the experimentally obtained total porosity for rocks. The proposed concept is also applicable to other modes of imaging, including thin-section light microscopy, scanning electron microscopy, and synchrotron source micro-CT.

Synthesis and characterization of nickel doped zinc selenide nanospheres for nonlinear optical applications

Phase purity plays an important role in determining the properties of the material and its subsequent applications which depends on the synthesis conditions and dopant concentrations. Phase pure zinc selenide and nickel doped zinc selenide nanoparticles were synthesized by hydrothermal method using sodium selenite as precursor. Calculated crystallite size for various compositions showed a decrease with dopant concentration with the values around 10 nm and less. Morphological analysis showed the formation of spherical particles which is distinct in the micron scale image. SAED pattern showed the formation of nanocrystalline particles with particles size varying between 10 and 20 nm. Quantum confinement effect due to reduced size was corroborated with increased band gap values as measured from diffuse reflectance spectra. Photoluminescence spectra showed the presence of dominant near band-edge emission along with certain defect level emissions for all the samples. Nonlinear optical studies carried out using a continuous wave laser showed an increase in nonlinear refractive index and susceptibility values with dopant concentration signifying the role of defects and the structural modifications occurring due to doping. The nonlinear optical properties exhibited by this material has been utilized for device applications like optical limiting and the results show enhancement in limiting efficiency with dopant concentrations.

Optical Evaluation of Enamel Microleakage with One-Step Self-Etch Adhesives.

In this in vitro study, cross-polarization optical coherence tomography (CP-OCT) was used to evaluate microleakage in dental composite restorations bonded to enamel with two types of one-step self-etching (SE) adhesives. One-step SE adhesives were proposed to simplify bonding of composite restorations. However, bonding of these simplified adhesive to dental enamel is still questionable. OCT is a promising diagnostic tool that allows micron-scale imaging of biological tissues and structures. Class-V cavities (4-mm diameter × 1-mm depth) were prepared on the labial surfaces of extracted human anterior teeth with margins and floor located in enamel. The cavities were then divided into two groups (n = 5) and restored with either Tetric N-Bond Universal (Ivoclar Vivadent, Liechtenstein) or Palfique Bond (Tokuyama Dental Corporation, Japan), followed by Estelite Flow Quick flowable composite (Tokuyama Dental Corporation). After storage in 100% humidity for 24 h, specimens were immersed in ammoniacal silver nitrate solution for another 24 h. Later, they were rinsed and immersed in photo-developing solution under fluorescent light for 8 h. CP-OCT at 1310 nm center wavelength was used to scan seven two-dimensional cross-sectional images from each specimen. Each cross-sectional image was analyzed using ImageJ software to quantify interfacial microleakage at the cavity floor. Student's t-test showed significant difference between the tested adhesives (p < 0.05). Palfique Bond adhesive presented inferior interfacial adaptation as it obtained higher values of floor microleakage compared to Tetric N-Bond Universal adhesive group. CP-OCT enabled nondestructive quantitative assessment of microleakage in enamel dental restorations.

Optical Coherence Tomography: Basic Concepts and Applications in Neuroscience Research.

Optical coherence tomography is a micrometer-scale imaging modality that permits label-free, cross-sectional imaging of biological tissue microstructure using tissue backscattering properties. After its invention in the 1990s, OCT is now being widely used in several branches of neuroscience as well as other fields of biomedical science. This review study reports an overview of OCT's applications in several branches or subbranches of neuroscience such as neuroimaging, neurology, neurosurgery, neuropathology, and neuroembryology. This study has briefly summarized the recent applications of OCT in neuroscience research, including a comparison, and provides a discussion of the remaining challenges and opportunities in addition to future directions. The chief aim of the review study is to draw the attention of a broad neuroscience community in order to maximize the applications of OCT in other branches of neuroscience too, and the study may also serve as a benchmark for future OCT-based neuroscience research. Despite some limitations, OCT proves to be a useful imaging tool in both basic and clinical neuroscience research.

Making Advanced Scientific Algorithms and Big Scientific Data Management More Accessible

Author(s): Venkatakrishnan, SV; Mohan, KA; Beattie, K; Correa, J; Dart, E; Deslippe, JR; Hexemer, A; Krishnan, H; MacDowell, AA; Marchesini, S; Patton, SJ; Perciano, T; Sethian, JA; Stromsness, R; Tierney, BL; Tull, CE; Ushizima, D; Parkinson, DY | Editor(s): Bouman, Charles A; Sauer, Ken D | Abstract: Synchrotrons such as the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory are user facilities - they are sources of extremely bright X-ray beams, and scientists come from all over the world to perform experiments that require these beams. As the complexity of experiments has increased, and the size and rates of data sets has exploded, managing, analyzing and presenting the data collected at synchrotrons has been an increasing challenge. The ALS has partnered with high performance computing, fast networking, and applied mathematics groups to create asuper-facility, giving users simultaneous access to the experimental, computational, and algorithmic resources to overcome this challenge. This combination forms an efficient closed loop, where data despite its high rate and volume is transferred and processed, in many cases immediately and automatically, on appropriate compute resources, and results are extracted, visualized, and presented to users or to the experimental control system, both to provide immediate insight and to guide decisions about subsequent experiments during beam-time. In this paper, We will present work done on advanced tomographic reconstruction algorithms to support users of the 3D micron-scale imaging instrument (Beamline 8.3.2, hard X-ray micro-tomography).

MP74-17 POTENTIAL OF OPTICAL COHERENCE TOMOGRAPHY (OCT) AND PROBE-BASED CONFOCAL LASERENDOMICROSCOPY (PCLE) IN THE INVESTIGATION OF THE TESTIS – A FEASIBILITY STUDY

You have accessJournal of UrologyInfertility: Therapy1 Apr 2015MP74-17 POTENTIAL OF OPTICAL COHERENCE TOMOGRAPHY (OCT) AND PROBE-BASED CONFOCAL LASERENDOMICROSCOPY (PCLE) IN THE INVESTIGATION OF THE TESTIS – A FEASIBILITY STUDY Matthias Trottmann, Sabine Kölle, Christian Homann, Herbert Stepp, Daniel Döring, Regina Leeb, Sven Reese, Christian G. Stief, and Ronald Sroka Matthias TrottmannMatthias Trottmann More articles by this author , Sabine KölleSabine Kölle More articles by this author , Christian HomannChristian Homann More articles by this author , Herbert SteppHerbert Stepp More articles by this author , Daniel DöringDaniel Döring More articles by this author , Regina LeebRegina Leeb More articles by this author , Sven ReeseSven Reese More articles by this author , Christian G. StiefChristian G. Stief More articles by this author , and Ronald SrokaRonald Sroka More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.2672AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Male infertility is often due to azoospermia which is mainly addressed surgically by testicular sperm extraction. As no imaging technique for the detection of spermatozoa in vivo is available to date, the positive sperm retrieval rate is merely 50%. Therefore the aim of this study was the investigation of the potential of probe-based confocal laser endomicroscopy (pCLE) and optical coherence tomography (OCT) for micron-scale imaging of testis microarchitecture. METHODS Specimens of bovine testes and epididymides were obtained after slaughter (n=14). For OCT imaging FDA-approved probe-based Niris Imaging System (probe diameter 2.7 mm; axial resolution (AR) 10-20 μm, lateral resolution (LR) 25-50 μm; 1310 nm, Imalux, Cleveland, Ohio, USA) and microscopic style OCT system (AR 5 μm; LR 8-15μ m; Telesto 1325 nm, Ganymede 930 nm, Thorlabs Inc., Dachau, Germany) were used. All obtained images were compared to histological findings after H&E staining. For pCLE Cellvizio® system (Mauna Kea Technologies, France) images were correlated to those obtained by confocal laser microscopy, light microscopy and phase contrast microscopy. For pCLE, the probes ProFlex™ S1500 (LR 3.3 μm; surface imaging) and ProFlex™ Ultra Mini O (LR 1.4 μm; imaging depth of 60 μm) were used. As fluorescent agents 0.001% fluorescein isothiocyanate (FITC), 5% cresyl violet solution (CV), 0,001% TO-PRO®-3 Iodide (T3) and 0.04 % acriflavine (AF) were used. RESULTS By microscopic OCT imaging the testicular and epididymal microarchitecture including ducts and tubules could be identified. Furthermore intra-tubular content and diameter of the tubules could be were analysed. As optical resolution of probe-based Niris Imaging System was distinctly reduced, imaging of testicular tissue did not provide detailed information on single spermatozoa. By pCLE real-time imaging, cells of spermatogenesis and supporting Leydig cells could be identified as well as different cell compartments in the testis. Contrary to OCT, single viable spermatozoa were identified. CONCLUSIONS Microscopic OCT and pCLE techniques looks promising for ex-vivo imaging of specific testicular tissue areas thus discovering spermatozoa fertile areas looks feasible. In comparison to pCLE OCT does not need any fluorescence labelling. The results imply that application of these novel imaging techniques might improve sperm retrieval rates during testicular sperm extraction (TESE) by optical guidance. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e945-e946 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Matthias Trottmann More articles by this author Sabine Kölle More articles by this author Christian Homann More articles by this author Herbert Stepp More articles by this author Daniel Döring More articles by this author Regina Leeb More articles by this author Sven Reese More articles by this author Christian G. Stief More articles by this author Ronald Sroka More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Synchrotron radiation imaging is a powerful tool to image brain microvasculature

Synchrotron radiation (SR) imaging is a powerful experimental tool for micrometer-scale imaging of microcirculation in vivo. This review discusses recent methodological advances and findings from morphological investigations of cerebral vascular networks during several neurovascular pathologies. In particular, it describes recent developments in SR microangiography for real-time assessment of the brain microvasculature under various pathological conditions in small animal models. It also covers studies that employed SR-based phase-contrast imaging to acquire 3D brain images and provide detailed maps of brain vasculature. In addition, a brief introduction of SR technology and current limitations of SR sources are described in this review. In the near future, SR imaging could transform into a common and informative imaging modality to resolve subtle details of cerebrovascular function.

Micro-X-ray fluorescence-based comparison of skeletal structure and P, Mg, Sr, O and Fe in a fossil of the cold-water coral Desmophyllum sp., NW Pacific

Micro-scale distributions of trace and minor elements in, for example, coral skeletons are crucial as geochemical tracers of past environmental conditions, because they have the inherent advantage of accounting for confounding diagenetic and physiological effects. To extract reproducible paleoceanographic records from coral skeletons, a selective measurement of specific ultrastructures at high spatial resolution is required. Compared to warm-water reef-building corals, such data are limited in cold-water corals and, to the best of the authors’ knowledge, the latter have to date not been examined by means of micro-X-ray fluorescence. This technique was used for micrometer-scale imaging of P, Mg, Sr, O, and Fe intensities (counts per unit time) in a fossil specimen (as yet unknown age) of the cold-water coral Desmophyllum sp. from surface sediments of the NW Pacific. Cross plots confirmed that the micro-XRF signals were associated with corresponding trends in elemental concentration (ppm). Two major structural components of the septum—centers of calcification (COCs) and the surrounding fibrous aragonite portion—differed in composition. The COCs were characterized by higher intensities of P and Mg (650 and 220 counts per 5 s, respectively), and lower intensities of Sr (2,800) and O (580; corresponding values for the fibrous aragonite are 370, 180, 3,300 and 620 counts per 5 s, respectively). Oxygen intensity values were mostly homogeneous, but slightly lower in COCs and substantially higher in a well-defined patch in the fibrous aragonite. The mostly homogeneous P signals in the fibrous aragonite confirm the utility of this structural component and of coral septa in general for tracer studies of oceanic P. Nevertheless, spot occurrences of elevated P (>950 counts per 5 s) spanning tens of micrometers in specific parts of the fibrous region of the septum would cause overestimates of oceanic P, and should evidently not be overlooked in future research. The distribution of Fe showed no correlation with P, indicating no significant contamination in the form of P-bearing diagenetic ferromanganese precipitates. Such hotspots plausibly reflect the presence of other mineral phases, such as crystalline hydroxylapatite inclusions or contamination with organic material. The P signal intensity was positively correlated with Mg (r=0.553, p<0.001), and negatively with Sr (r=–0.489, p<0.001) and O (r=–0.311, p<0.001). There was no discernible evidence of control by water temperature in the Sr distribution pattern. These findings establish micro-X-ray fluorescence as a highly suitable pre-screening tool in cold-water coral sclerochronology, which can serve to refine sampling strategies without sample damage, and complement other micrometer-scale spatial distribution analyses of elements (notably, Ca) based on well-known approaches involving micro-milling, electron microprobes, secondary ion mass spectrometry, and laser ablation.