Volumetric Resolution Research Articles

Spatial proteomics of single cells and organelles on tissue slides using filter-aided expansion proteomics.

Hydrogel-based tissue expansion combined with mass spectrometry (MS) offers an emerging spatial proteomics approach. Here, we present a filter-aided expansion proteomics (FAXP) strategy for spatial proteomics analysis of archived formalin-fixed paraffin-embedded (FFPE) specimens. Compared to our previous ProteomEx method, FAXP employed a customized tip device to enhance both the stability and throughput of sample preparation, thus guaranteeing the reproducibility and robustness of the workflow. FAXP achieved a 14.5-fold increase in volumetric resolution. It generated over 8 times higher peptide yield and a 255% rise in protein identifications while reducing sample preparation time by 50%. We also demonstrated the applicability of FAXP using human colorectal FFPE tissue samples. Furthermore, for the first time, we achieved bona fide single-subcellular proteomics under image guidance by integrating FAXP with laser capture microdissection.

Assessing the 3D resolution of refocused correlation plenoptic images using a general-purpose image quality estimator

Correlation plenoptic imaging (CPI) is emerging as a promising approach to light-field imaging (LFI), a technique enabling simultaneous measurement of light intensity distribution and propagation direction from a scene. LFI allows single-shot 3D sampling, offering fast 3D reconstruction for a wide range of applications. However, the array of micro-lenses typically used in LFI to obtain 3D information limits image resolution, which rapidly declines with enhanced volumetric reconstruction capabilities. CPI addresses this limitation by decoupling the measurement of the light field on two photodetectors with spatial resolution, eliminating the need for micro-lenses. 3D information is encoded in a four-dimensional correlation function, which is decoded in post-processing to reconstruct images without the resolution loss seen in conventional LFI. This paper evaluates the tomographic performance of CPI, demonstrating that the refocusing reconstruction method provides axial sectioning capabilities comparable to conventional imaging systems. A general-purpose analytical approach based on image fidelity is proposed to quantitatively study axial and lateral resolution. The analysis fully characterizes the volumetric resolution of any CPI architecture, offering a comprehensive evaluation of its imaging performance.

SMERF: Streamable Memory Efficient Radiance Fields for Real-Time Large-Scene Exploration

Recent techniques for real-time view synthesis have rapidly advanced in fidelity and speed, and modern methods are capable of rendering near-photorealistic scenes at interactive frame rates. At the same time, a tension has arisen between explicit scene representations amenable to rasterization and neural fields built on ray marching, with state-of-the-art instances of the latter surpassing the former in quality while being prohibitively expensive for real-time applications. We introduce SMERF, a view synthesis approach that achieves state-of-the-art accuracy among real-time methods on large scenes with footprints up to 300 m 2 at a volumetric resolution of 3.5 mm 3 . Our method is built upon two primary contributions: a hierarchical model partitioning scheme, which increases model capacity while constraining compute and memory consumption, and a distillation training strategy that simultaneously yields high fidelity and internal consistency. Our method enables full six degrees of freedom navigation in a web browser and renders in real-time on commodity smartphones and laptops. Extensive experiments show that our method exceeds the state-of-the-art in real-time novel view synthesis by 0.78 dB on standard benchmarks and 1.78 dB on large scenes, renders frames three orders of magnitude faster than state-of-the-art radiance field models, and achieves real-time performance across a wide variety of commodity devices, including smartphones. We encourage readers to explore these models interactively at our project website: https://smerf-3d.github.io.

Virtual cylindrical PET for efficient DOI image reconstruction with sub-millimetre resolution

Objective. Image reconstruction in high resolution, narrow bore PET scanners with depth of interaction (DOI) capability presents a substantial computational challenge due to the very high sampling in detector and image space. The aim of this study is to evaluate the use of a virtual cylinder in reducing the number of lines of response (LOR) for DOI-based reconstruction in high resolution PET systems while maintaining uniform sub-millimetre spatial resolution. Approach. Virtual geometry was investigated using the awake animal mousePET as a high resolution test case. Using GEANT4 Application for Tomographic Emission (GATE), we simulated the physical scanner and three virtual cylinder implementations with detector size 0.74 mm, 0.47 mm and 0.36 mm (vPET1, vPET2 and vPET3, respectively). The virtual cylinder condenses physical LORs stemming from various crystal pairs and DOI combinations, and which intersect a single virtual detector pair, into a single virtual LOR. Quantitative comparisons of the point spread function (PSF) at various positions within the field of view (FOV) were compared for reconstructions based on the vPET implementations and the physical scanner. We also assessed the impact of the anisotropic PSFs by reconstructing images of a micro Derenzo phantom. Main results. All virtual cylinder implementations achieved LOR data compression of at least 50% for DOI PET reconstruction. PSF anisotropy in radial and tangential profiles was chiefly influenced by DOI resolution and only marginally by virtual detector size. Spatial degradation introduced by virtual cylinders was most prominent in the axial profile. All virtual cylinders achieved sub-millimetre volumetric resolution across the FOV when 6-bin DOI reconstructions (3.3 mm DOI resolution) were performed. Using vPET2 with 6 DOI bins yielded nearly identical reconstructions to the non-virtual case in the transaxial plane, with an LOR compression factor of 86%. Resolution modelling significantly reduced the effects of the asymmetric PSF arising from the non-cylindrical geometry of mousePET. Significance. Narrow bore and high resolution PET scanners require detectors with DOI capability, leading to computationally demanding reconstructions due to the large number of LORs. In this study, we show that DOI PET reconstruction with 50%–86% LOR compression is possible using virtual cylinders while maintaining sub-millimetre spatial resolution throughout the FOV. The methodology and analysis can be extended to other scanners with DOI capability intended for high resolution PET imaging.

Visualizing cortical blood perfusion after photothrombotic stroke in vivo by needle-shaped beam optical coherence tomography angiography

Optical imaging techniques provide low-cost, non-radiative images with high spatiotemporal resolution, making them advantageous for long-term dynamic observation of blood perfusion in stroke research and other brain studies compared to non-optical methods. However, high-resolution imaging in optical microscopy fundamentally requires a tight optical focus, and thus a limited depth of field (DOF). Consequently, large-scale, non-stitched, high-resolution images of curved surfaces, like brains, are difficult to acquire without z-axis scanning. To overcome this limitation, we developed a needle-shaped beam optical coherence tomography angiography (NB-OCTA) system, and for the first time, achieved a volumetric resolution of less than 8 μm in a non-stitched volume space of 6.4 mm × 4 mm × 620 μm in vivo. This system captures the distribution of blood vessels at 3.4-times larger depths than normal OCTA equipped with a Gaussian beam (GB-OCTA). We then employed NB-OCTA to perform long-term observation of cortical blood perfusion after stroke in vivo, and quantitatively analyzed the vessel area density (VAD) and the diameters of representative vessels in different regions over 10 days, revealing different spatiotemporal dynamics in the acute, sub-acute and chronic phase of post-ischemic revascularization. Benefiting from our NB-OCTA, we revealed that the recovery process is not only the result of spontaneous reperfusion, but also the formation of new vessels. This study provides visual and mechanistic insights into strokes and helps to deepen our understanding of the spontaneous response of brain after stroke.

Creating high-resolution 3D cranial implant geometry using deep learning techniques.

Creating a personalized implant for cranioplasty can be costly and aesthetically challenging, particularly for comminuted fractures that affect a wide area. Despite significant advances in deep learning techniques for 2D image completion, generating a 3D shape inpainting remains challenging due to the higher dimensionality and computational demands for 3D skull models. Here, we present a practical deep-learning approach to generate implant geometry from defective 3D skull models created from CT scans. Our proposed 3D reconstruction system comprises two neural networks that produce high-quality implant models suitable for clinical use while reducing training time. The first network repairs low-resolution defective models, while the second network enhances the volumetric resolution of the repaired model. We have tested our method in simulations and real-life surgical practices, producing implants that fit naturally and precisely match defect boundaries, particularly for skull defects above the Frankfort horizontal plane.

Exploiting volumetric wave correlation for enhanced depth imaging in scattering medium

Imaging an object embedded within a scattering medium requires the correction of complex sample-induced wave distortions. Existing approaches have been designed to resolve them by optimizing signal waves recorded in each 2D image. Here, we present a volumetric image reconstruction framework that merges two fundamental degrees of freedom, the wavelength and propagation angles of light waves, based on the object momentum conservation principle. On this basis, we propose methods for exploiting the correlation of signal waves from volumetric images to better cope with multiple scattering. By constructing experimental systems scanning both wavelength and illumination angle of the light source, we demonstrated a 32-fold increase in the use of signal waves compared with that of existing 2D-based approaches and achieved ultrahigh volumetric resolution (lateral resolution: 0.41 mu m, axial resolution: 0.60 mu m) even within complex scattering medium owing to the optimal coherent use of the broad spectral bandwidth (225 nm).

479 Chronic Subdural Hematomas Treated With Surgical Evacuation Versus Standalone Middle Meningeal Artery Embolization: Volumetric Resolution in Immediate, Early and Late Follow-Up in a Propensity Matched Cohort

INTRODUCTION: Literature comparing surgery and middle meningeal artery embolization (MMAE) for chronic subdural hematomas (cSDH) is limited by patient selection bias. Furthermore, most studies do not perform volumetric measurements over time when comparing these two modalities. METHODS: Retrospective search of our database to include cSDH patients managed with either SEA or standalone MMAE. Propensity-score-matching was performed for axial and coronal lengths, maximum diameter and midline shift. Volumes of cSDH were measured at 24 h post-procedure, 3-12-weeks, 12-24-weeks, 24-36-weeks, 36-48-weeks and 48-60-weeks. RESULTS: Forty-eight matched hematoma pairs were obtained. The groups were also similar in demographics, comorbidities, medications and symptoms. Median volume was significantly lower at 24 h in the SEA group (SEA, 12.6 mL vs MMAE, 52.7 mL, P < 0.001). Median volume reduction was significantly greater in the SEA group at 24 h (SEA, 39.1 mL vs MMAE, 8.8 mL, P < 0.001) and in the 3-12 weeks interval (SEA, 50.8 mL vs MMAE, 23.7 mL, P < 0.001). The SEA group had significantly greater median resolution rate at 24 h (39.1 mL/day vs 8.8 mL/day, P < 0.001) and in the 3 to 12 weeks interval (1 mL/day vs 0.4 mL/day, P < 0.001) but not in remaining intervals. Near complete resolution at the 3 to 12 interval (SEA, 26.1% vs MMAE, 28%, P = 1) and 12 to 60 weeks interval (SEA, 78.3% vs MMAE, 80%, P = 1) was not significantly different between the groups. Overall, the recurrence was significantly higher in the SEA group than in the MMAE group (22.9% vs 4.2%, P = 0.01). CONCLUSIONS: In comparable cSDH patients, surgical evacuation resulted in better volumetric outcomes in the immediate and early follow-up periods but in extended follow-up intervals. Furthermore, surgical patients experienced a significantly higher rate of recurrence.

Investigation of Novel Preclinical Total Body PET Designed With J-PET Technology: A Simulation Study

The growing interest in human-grade total body positron emission tomography (PET) systems has also application in small animal research. Due to the existing limitations in human-based studies involving drug development and novel treatment monitoring, animal-based research became a necessary step for testing and protocol preparation. In this simulation-based study two unconventional, cost-effective small animal total body PET scanners (for mouse and rat studies) have been investigated in order to inspect their feasibility for preclinical research. They were designed with the novel technology explored by the Jagiellonian-PET (J-PET) Collaboration. Two main PET characteristics: sensitivity and spatial resolution were mainly inspected to evaluate their performance. Moreover, the impact of the scintillator dimension and time-of-flight on the latter parameter was examined in order to design the most efficient tomographs. The presented results show that for mouse TB J-PET the achievable system sensitivity is equal to 2.35% and volumetric spatial resolution to 9.46 ± 0.54 mm3, while for rat TB J-PET they are equal to 2.6% and 14.11 ± 0.80 mm3, respectively. Furthermore, it was shown that the designed tomographs are almost parallax-free systems, hence, they resolve the problem of the acceptance criterion tradeoff between enhancing spatial resolution and reducing sensitivity.

Computational study of boundary layer effects on stochastic rotor blade vortex shedding noise

This work entailed the use of lattice-Boltzmann simulations to investigate the effects of different sUAS rotor blade surface treatments, volumetric grid resolutions, and surface roughness heights on broadband noise prediction. Aerodynamic results showed trailing edge flow separation and a mispredicted laminar separation bubble for the laminar-to-turbulent transitional wall-function case and the fully-turbulent wall-function case as well as a transition front for the laminar-to-turbulent transitional wall-function case. It was seen that the current version of PowerFLOW (6-2021) cannot predict turbulent structures associated with turbulent wall-bounded flow unless a triggering mechanism (e.g., boundary layer trip) is employed, possibly explaining aerodynamic force and broadband noise underprediction. Tonal noise results showed thickness (i.e., geometry dependent) noise dominance at out-of-plane observers located above the rotor plane for the fundamental blade passage frequency and at all observer locations for the second harmonic of the blade passage frequency. Extrapolation techniques were also successfully used over broadband noise results to separate regions of underpredicted broadband noise caused by inadequate spatial resolution from other underpredicted regions caused by the misprediction of flow physics using the current computational strategy.

Volumetric resolution of chronic subdural hematomas treated with surgical evacuation versus middle meningeal artery embolization during immediate, early, and late follow up: propensity-score matched cohorts

BackgroundLiterature on volumetric resolution and recurrence over time between surgical evacuation alone (SEA) and standalone middle meningeal artery embolization (MMAE) in comparable chronic subdural hematoma (cSDH) patients is limited.MethodsA retrospective...

Effective Spatial Resolution of Photon Counting CT for Imaging of Trabecular Structures is Superior to Conventional Clinical CT and Similar to High Resolution Peripheral CT.

Photon counting computed tomography (PCCT) might offer an effective spatial resolution that is significantly improved compared with conventional state-of-the-art computed tomography (CT) and even provide a microstructural level of detail similar to high-resolution peripheral CT (HR-pQCT). The aim of this study was to evaluate the volumetric effective spatial resolution of clinically approved PCCT as an alternative to HR-pQCT for ex vivo or preclinical high-resolution imaging of bone microstructure. The experiment contained 5 human vertebrae embedded in epoxy resin, which were scanned 3 times each, and on 3 different clinical CT scanners: a PCCT (Naeotom Alpha), a dual-energy CT (Somatom Force [SF]), and a single-energy CT (Somatom Sensation 40 [S40]), all manufactured by Siemens Healthineers (Erlangen, Germany). Scans were performed with a tube voltage of 120 kVp and, to provide maximum scan performance and minimum noise deterioration, with exposures of 1500 mAs (SF), 2400 mAs (S40), and 4500 mAs (PCCT) and low slice increments of 0.1 (PCCT) and 0.3 mm (SF, S40). Images were reconstructed with sharp and very sharp bone kernels, Br68 and Br76 (PCCT), Br64 (SF), and B65s and B75h (S40). Ground truth information was obtained from an XtremeCT scanner (Scanco, Brüttisellen, Switzerland). Voxel-wise comparison was performed after registration, calibration, and resampling of the volumes to isotropic voxel size of 0.164 mm. Three-dimensional point spread- and modulation-transfer functions were calculated with Wiener's deconvolution in the anatomical trabecular structure, allowing optimum estimation of device- and kernel-specific smoothing properties as well as specimen-related diffraction effects on the measurement. At high contrast (modulation transfer function [MTF] of 10%), radial effective resolutions of PCCT were 10.5 lp/cm (minimum resolvable object size 476 μm) for kernel Br68 and 16.9 lp/cm (295 μm) for kernel Br76. At low contrast (MTF 5%), radial effective spatial resolutions were 10.8 lp/cm (464 μm) for kernel Br68 and 30.5 lp/cm (164 μm) for kernel Br76. Axial effective resolutions of PCCT for both kernels were between 27.0 (185 μm) and 29.9 lp/cm (167 μm). Spatial resolutions with kernel Br76 might possibly be still higher but were technically limited by the isotropic voxel size of 164 μm. The effective volumetric resolutions of PCCT with kernel Br76 ranged between 61.9 (MTF 10%) and 222.4 (MTF 5%) elements per cubic mm. Photon counting CT improved the effective volumetric resolution by factor 5.5 (MTF 10%) and 18 (MTF 5%) compared with SF and by a factor of 8.7 (MTF 10%) and 20 (MTF 5%) compared with S40. Photon counting CT allowed obtaining similar structural information as HR-pQCT. The effective spatial resolution of PCCT in trabecular bone imaging was comparable with that of HR-pQCT and more than 5 times higher compared with conventional CT. For ex vivo samples and when patient radiation dose can be neglected, PCCT allows imaging bone microstructure at a preclinical level of detail.

Utility of Maximum Intensity Projections in Volumetric High Resolution Computed Tomography Lung in the Evaluation of Diffuse Lung Diseases- A Retrospective Analysis

Introduction: Though volumetric High Resolution Computed Tomography (HRCT) has increased the sensitivity of diagnosing diffuse lung diseases, there are some drawbacks related with lesion detection. Post processing techniques like Maximum Intensity Projection (MIP) can help in increasing the sensitivity of HRCT further. Aim: To study various possible utilities of MIP in HRCT lung. Materials and Methods: A retrospective cross-sectional study was done in a tertiary care hospital, including all Computed Tomography (CT) scans performed in July 2020 to August 2020, with multiple lung findings and diffuse involvement of lungs. Two radiologists reviewed the base mean axial images of 1 mm and MIP images in sliding scale from 2 to 10 mm in lung window. They recorded the findings in every scan based on widely accepted basic pattern of interpretation of HRCT thorax. The slice/slab thickness that best depicted each finding was noted. Inter reader agreement was calculated for each finding. Results: Fifty nine CT cases, which included scans of 34 males and 25 female patients with a mean age of 37.4±12.5 years were reviewed. There was near perfect to substantial agreement between the two radiologists on various findings (kappa > 0.75). MIP images of 6-10 mm slab thickness were best suited to detect smaller nodules, assess vessel size in areas of mosaic attenuation and detect dense lesions in images with poor breath hold. The MIP images of 2-5 mm thickness were useful in detecting the location in relation to secondary pulmonary lobule, reticular densities and crazy-paving densities. Conclusion: The MIP being an easy to use and readily available post processing technique, when used with volumetric HRCT dataset of thorax enhanced the value of HRCT in detecting various lesions.

Development of an Integrated C-Arm Interventional Imaging System With a Strip Photon Counting Detector and a Flat Panel Detector.

Modern interventional x-ray systems are often equipped with flat-panel detector-based cone-beam CT (FPD-CBCT) to provide tomographic, volumetric, and high spatial resolution imaging of interventional devices, iodinated vessels, and other objects. The purpose of this work was to bring an interchangeable strip photon-counting detector (PCD) to C-arm systems to supplement (instead of retiring) the existing FPD-CBCT with a high quality, spectral, and affordable PCD-CT imaging option. With minimal modification to the existing C-arm, a 51×0.6 cm2 PCD with a 0.75 mm CdTe layer, two energy thresholds, and 0.1 mm pixels was integrated with a Siemens Artis Zee interventional imaging system. The PCD can be translated in and out of the field-of-view to allow the system to switch between FPD and PCD-CT imaging modes. A dedicated phantom and a new algorithm were developed to calibrate the projection geometry of the narrow-beam PCD-CT system and correct the gantry wobbling-induced geometric distortion artifacts. In addition, a detector response calibration procedure was performed for each PCD pixel using materials with known radiological pathlengths to address concentric artifacts in PCD-CT images. Both phantom and human cadaver experiments were performed at a high gantry rotation speed and clinically relevant radiation dose level to evaluate the spectral and non-spectral imaging performance of the prototype system. Results show that the PCD-CT system has excellent image quality with negligible artifacts after the proposed corrections. Compared with FPD-CBCT images acquired at the same dose level, PCD-CT images demonstrated a 53% reduction in noise variance and additional quantitative imaging capability.

Volumetric interferometric lattice light-sheet imaging.

Live-cell imaging with high spatiotemporal resolution and high detection sensitivity facilitates the study of the dynamics of cellular structure and function. However, extracting high-resolution 4D (3D space plus time) information from live cells remains challenging, because current methods are slow, require high peak excitation intensities or suffer from high out-of-focus background. Here we present 3D interferometric lattice light-sheet (3D-iLLS) imaging, a technique that requires low excitation light levels and provides high background suppression and substantially improved volumetric resolution by combining 4Pi interferometry with selective plane illumination. We demonstrate that 3D-iLLS has an axial resolution and single-particle localization precision of 100 nm (FWHM) and <10 nm (1σ), respectively. We illustrate the performance of 3D-iLLS in a range of systems: single messenger RNA molecules, nanoscale assemblies of transcription regulators in the nucleus, the microtubule cytoskeleton, and mitochondria organelles. The enhanced 4D resolution and increased signal-to-noise ratio (SNR) of 3D-iLLS will facilitate the analysis of biological processes at the sub-cellular level.

Towards Quantum 3D Imaging Devices

We review the advancement of the research toward the design and implementation of quantum plenoptic cameras, radically novel 3D imaging devices that exploit both momentum–position entanglement and photon–number correlations to provide the typical refocusing and ultra-fast, scanning-free, 3D imaging capability of plenoptic devices, along with dramatically enhanced performances, unattainable in standard plenoptic cameras: diffraction-limited resolution, large depth of focus, and ultra-low noise. To further increase the volumetric resolution beyond the Rayleigh diffraction limit, and achieve the quantum limit, we are also developing dedicated protocols based on quantum Fisher information. However, for the quantum advantages of the proposed devices to be effective and appealing to end-users, two main challenges need to be tackled. First, due to the large number of frames required for correlation measurements to provide an acceptable signal-to-noise ratio, quantum plenoptic imaging (QPI) would require, if implemented with commercially available high-resolution cameras, acquisition times ranging from tens of seconds to a few minutes. Second, the elaboration of this large amount of data, in order to retrieve 3D images or refocusing 2D images, requires high-performance and time-consuming computation. To address these challenges, we are developing high-resolution single-photon avalanche photodiode (SPAD) arrays and high-performance low-level programming of ultra-fast electronics, combined with compressive sensing and quantum tomography algorithms, with the aim to reduce both the acquisition and the elaboration time by two orders of magnitude. Routes toward exploitation of the QPI devices will also be discussed.

Combining X-ray Nano Tomography with focused ion beam serial section imaging — Application of correlative tomography to integrated circuits

In this research we show the combination of two sub-micrometer imaging techniques, namely focused ion beam (FIB) and scanning electron microscope (SEM)-based X-ray nano tomography, on the exact same sample, a fragment of a central processing unit (CPU). Based on its three-dimensional structure, we compare the volumetric measurement results in terms of scanned volume, spatial resolution, visible details, and artifacts. For comparability reasons we limit the acquisition time to 24 h for both imaging modalities. By this comparison we evaluate the capability of our self-developed laboratory nano-computed tomography system (XRM-II nano-CT) as its performance and usability was increased by the recent upgrades.The nano-computed tomography (nano-CT) offers a 12 times larger scanned sample volume than the FIB tomography on the one hand, but a lower volumetric resolution combined with a factor of 5 lower sampling on the other. The main artifacts of the nano-CT are blurred structures caused by incomplete alignment during the reconstruction process, while in the FIB tomography curtain artifacts lead to distorted structures in the reconstructed volume.We give an outlook to combine the benefits of the two methods, where the nano-CT is used as a navigational scan for the FIB tomography to achieve the best resolution on a given part of a sample.

Recurrence and Coniglobus Volumetric Resolution of Subacute and Chronic Subdural Hematoma Post-Middle Meningeal Artery Embolization.

Objective: To study the efficacy of middle meningeal artery (MMA) embolization for the treatment of chronic subdural hematoma (SDH) and characterize its post-embolization volumetric resolution. Methods: Ten patients diagnosed with 13 cSDH underwent MMA embolization. SDH volumes were measured from time of initial discovery on imaging to pre-operative, post-operative, short-term and long-term follow-up. Time between procedure to obliteration was also measured. Volumetric analysis was done using the coniglobus formula, and recurrence rate as well as resolution timeline was defined using best-fit models. Results: Out of 10 patients, five were recurrent lesions, three were bilateral and seven unilateral cSDH. Average and median pre-operative volumes were 105.3 cc and 97.4 cc, respectively. Embolization on average was performed 21 days after discovery. Sixty percent of patients had concurrent antiplatelets or anticoagulation use. Forty percent underwent embolization treatment as the primary therapy. Recurrence was not seen in any patients treated with embolization. There were no peri- or post-operative complications. Five patients experienced complete or near-complete obliteration, while those with partial resolution showed a composite average of 75% volumetric reduction in 45 days. Post-embolization, the volumetric resolution followed an exponential decay curve over time and was independent of initial volume. Conclusion: MMA embolization contributed to a marked reduction in SDH volume post-operatively and can be used as a curative therapy for primary or recurrent chronic SDH.

Learning to Reconstruct Confocal Microscopy Stacks From Single Light Field Images

We present a novel deep learning approach to reconstruct confocal microscopy stacks from single light field images. To perform the reconstruction, we introduce LFMNet, a fully convolutional neural network architecture inspired by the U-Net design. A property of LFMNet is its ability to reconstruct with near confocal accuracy a 112 ×112 ×57.6 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> volume (1287×1287×64 voxels) in 50 ms given a single light field image of 1287×1287 pixels, thus dramatically reducing 720-fold the capture time compared to confocal scanning of assays at the same volumetric resolution and 64-fold the required storage. To prove its applicability in life sciences, our approach is evaluated both quantitatively and qualitatively on mouse brain slices with fluorescently labeled blood vessels. Because of the drastic reduction in image acquisition time, our setup and method are suitable for imaging highly dynamic and light-sensitive events, and in closed-loop systems, where latency due to the reconstruction time is crucial. We provide empirical analysis of the optical design, of the network architecture and of our training procedure to reconstruct confocal-like volumes for a given target depth range. To train our network, we built a data set of 362 light field images of the mouse brain sample and the corresponding aligned set of 3D confocal scans, which we use as ground truth. The data set will be made available for research purposes.

A Novel Sensor for In Situ Detection of Freeze‐Thaw Characteristics in Plants from Stem Temperature and Water Content Measurements

Freezing is a typical abiotic stress on plants, which can induce physiological damages of plants. A better understanding of plant freeze‐thaw characteristics contributes to solving some hot issues in plant physiology, such as cold resistance and cold acclimation. This article presents a novel sensor for in situ detection of freeze‐thaw characteristics in plants based on stem temperature and water content. The measuring circuit of stem temperature was designed based on constant current source and platinum resistance. The measuring circuit of stem water content was designed based on standing wave ratio and the dielectric properties of stem tissue. The temperature resolution of the compound sensor is less than 0.1°C. The MAE and RMSE of temperature measurement are approximately 0.57°C and 0.65°C, respectively. The volumetric water content resolution of the compound sensor is less than 0.05%. The MAE and RMSE of volumetric water content measurement are approximately 1.59% and 1.81%, respectively. Moreover, a mathematical model for describing the freeze‐thaw characteristics of plant stem was established and solved based on the compound sensor. Then, some freeze‐thaw indicators including stem water content, ice content, freezing depth, freezing velocity, thawing depth, and thawing velocity were solved and used to interpret the freeze‐thaw rules of plant stem. It can be concluded that the freeze‐thaw velocity is closely related to the physicochemical properties of plant stem which also change dynamically in the freeze‐thaw cycle.