Volume Reconstruction Research Articles

Stochastic alluvial fan and terrace formation triggered by a high-magnitude Holocene landslide in the Klados Gorge, Crete

Abstract. Alluvial fan and terrace formation is traditionally interpreted as a fluvial system response to Quaternary climate oscillations under the backdrop of slow and steady tectonic activity. However, several recent studies challenge this conventional wisdom, showing that such landforms can evolve rapidly as a geomorphic system responds to catastrophic and stochastic events, like large-magnitude mass wasting. Here, we contribute to this topic through a detailed field, geochronological, and numerical modelling investigation of thick (>50 m) alluvial sequences in the Klados catchment in southwestern Crete, Greece. The Klados River catchment lies in a Mediterranean climate, is largely floored by carbonate bedrock, and is characterised by well-preserved alluvial terraces and inset fans at the river mouth that exceed the volumes of alluvial deposits in neighbouring catchments of similar size. Previous studies interpreted the genesis and evolution of these deposits to result from a combination of Pleistocene sea-level variation and the region's long-term tectonic activity. We show that the >20 m thick lower fan unit, previously thought to be late Pleistocene in age, unconformably buries a paleoshoreline uplifted in the first centuries CE, placing the depositional age of this unit firmly in the late Holocene. The depositional timing is supported by seven new radiocarbon dates that indicate middle to late Holocene ages for the entire fan and terrace sequence. Furthermore, we report new evidence of a previously unidentified valley-filling landslide deposit that is locally 100 m above the modern stream elevation, and based on cross-cutting relationships, it predates the alluvial sequence. Observations indicate the highly erodible landslide deposit as the source of the alluvial fill sediment. We identify the likely landslide detachment area as a large rockfall scar at the steepened head of the catchment. A landslide volume of 9.08×107 m3 is estimated based on volume reconstructions of the mapped landslide deposit and the inferred scar location. We utilise landslide runout modelling to validate the hypothesis that a high-magnitude rockfall would pulverise and send material downstream, filling the valley up to ∼100 m. This partial liquefaction is required for the rockfall to form a landslide body of the extent observed in the valley and is consistent with the sedimentological characteristics of the landslide deposit. Based on the new age control and the identification of the landslide deposit, we hypothesise that the rapid post-landslide aggradation and incision cycles of the alluvial deposits are not linked to long-term tectonic uplift or climate variations but rather stochastic events such as mobilisation of sediment in large earthquakes, storm events, or ephemeral blockage in the valley's narrow reaches. The Klados case study represents a model environment for how stochastically driven events can mimic climate-induced sedimentary archives and lead to deposition of thick alluvial sequences within hundreds to thousands of years, and it illustrates the ultrasensitivity of mountainous catchments to external perturbations after catastrophic events.

4: Four-flap Breast Reconstruction: Assessing Breast-q And Donor Site Morbidity In Bilateral Stacked Autologous Breast Reconstruction

Purpose:Patients undergoing bilateral autologous breast reconstruction may benefit from increased flap volume using bilateral stacked deep inferior epigastric perforator (DIEP) and profunda artery perforator (PAP) flaps. Four-flap reconstruction patients are a unique population in which to compare donor site morbidity of the two most commonly used free flaps in breast reconstruction (DIEP and PAP). Our aim was to characterize the donor site morbidity and overall patient outcomes of four-flap breast reconstruction patients.Methods:Retrospective chart review was performed for all patients undergoing four-flap breast reconstruction by two surgeons between 2014-2019 at a single academic medical center. Inpatient surgical site pain location and pain scores by Numeric Pain Rating Scale (NPRS) were recorded during the immediate post-operative admission. All patients were contacted to complete the BREAST-Q reconstructive module and the Lower Extremity Functional Scale (LEFS). Four-flap BREAST-Q scores were compared to bilateral DIEP and to bilateral PAP patients as reference populations.Results:A total of 63 patients undergoing four-flap breast reconstruction were identified. BREAST-Q (n=38) scores demonstrated mean Satisfaction With Breasts of 66.1+/-32.2, Psychosocial Well-Being 70.8+/-34.3, Sexual Well-Being 44.5+/-36.5, Physical Well-Being Chest 72.8+/-32.5, and Physical Well-Being Abdomen 63.6+/-34.9. In comparison to bilateral DIEP (n=180), and bilateral PAP reconstruction patients (n=43), four-flap BREAST-Q scores were similar. No difference in BREAST-Q scores remained after matching four-flap patients to bilateral DIEP patients by Age, Race, BMI, Zip Code, and radiation history. With regard to donor site morbidity, mean instances of donor site pain location recorded at the abdomen (9.72, 95%CI[7.78-11.66]) were significantly higher than the thigh (2.82, 95%CI[1.63-4.00]) during the post-operative admission (p=<0.0001). Mean pain scores by NPRS were similar between abdomen, thigh, and breast surgical sites. Subjective survey data revealed more donor site pain at the PAP site, a patient preference for the DIEP donor site, and easier post-operative care for the DIEP donor site. Further, a majority of patients felt the thighs were aesthetically improved post-operatively (54.29%). Long term survey outcomes from the LEFS (n=35) demonstrated a mean score of 92.4% (SD 10.9). The majority of women would make the same decision for four flap breast reconstruction (81.82%).Conclusion:This is the largest consecutive series of four-flap breast reconstruction outcomes reported to date. Patients undergoing four-flap breast reconstruction have more immediate donor site pain at the abdomen than the thigh, but more thigh pain after discharge home once ambulating. BREAST-Q scores in four-flap patients demonstrate overall high patient satisfaction that is similar to both bilateral DIEP and bilateral PAP reconstruction patients. In patients who require increased flap volume for body appropriate breast reconstruction, four-flap reconstruction is comparable to bilateral DIEP and bilateral PAP by BREAST-Q scores.

Unsupervised Generative Adversarial Network for 3-D Microstructure Synthesis from 2-D Image

Three-dimensional microstructure reconstruction is indispensable for understanding the performance and reliability of SOFC electrodes. Not only the microstructure parameters, but also SOFC electrochemical characteristics such as overpotentials can be calculated when combined with numerical simulations. The most common method to analyze 3-D structures with a feature size of 0.01 – 10 μm is a focused ion beam - scanning electron microscope (FIB-SEM). However, there’s a tradeoff between reconstruction volume size and resolution. Besides, in order to obtain high quality reconstruction, accumulation of know-hows for pre and post-processing is required. Therefore, fast screening of the microstructures is not easy for FIB-SEM due to the difficulty of measurement. On the other hand, a single SEM image can be obtained very easily. An arising question is if it is possible to extract properties of microstructures and numerically synthesize 3-D model directly from a single 2-D SEM image.In recent years, machine learning techniques have become a powerful tool for image processing. Nevertheless, applications of machine learning in the field of porous materials, in particular fuel cells and batteries are still limited. The previous works concentrated on relatively simple artificial neural networks (ANN), but the class of neural networks that can effectively analyze visual images is the convolutional neural network (CNN). Gayon-Lombardo et al. (1) demonstrated a successful application of generative adversarial network (GAN) based on CNN layers to fabricate synthetic 3-D SOFC microstructures. It is indicated that the GAN-based approach can be very effective, but the algorithm requires 3-D teaching data (GAN3Dto3D).In the scope of this research, a novel method for fabrication of synthetic 3-D microstructure directly from a 2-D SEM image is proposed (Fig. 1A). The GAN2Dto3D network consists of a 3-D microstructure generator and a discriminator which operate on 2-D data. Each microstructure fabricated by the generator is treated as a set of individual cross-sectional 2-D images. The discriminator checks the validity of each 2-D slice in the generated microstructure in all spatial directions (height, width and thickness). Patches extracted from a real 2-D cross-section image are used as training data. In each training iteration, new random patches are extracted to increase the number of available training data. Additionally, the training images are augmented by random horizontal and vertical flipping. As all of the cross-section of the newly generated microstructure has to be statistically equivalent to the real 2-D cross-section, the generated 3-D microstructure is smooth in all spatial directions.The GAN2Dto3D approach is tested on the dataset of real SOFC microstructures. For the real microstructure, a set of nickel (Ni) – gadolinium doped ceria (GDC) microstructures was fabricated. All composite anode samples were prepared with NiO (AGC Seimi, Japan) and GDC (Gd0.1Ce0.9O ShinEtsu, Japan) powders mixed in a designated proportion and sintered at 1350 oC. Differences in the structure are due to the initial anode slurry composition and packing density. The solid phase fractions were controlled by GDC share in the composite in the range of 30 – 70 vol.%, and their porosity was controlled by isostatic pressing (2). 3-D microstructures were reconstructed by FIB-SEM and used as the ground truth data for the validation of GAN2Dto3D model. The results of the GAN2Dto3D algorithm applied to generate two synthetic microstructures with different GDC share and the porosity are shown in Fig. 1B and 1C. The size of the generated microstructures is 64 × 64 × 64 voxels, which is equivalent to 6.4 × 6.4 × 6.4 µm. The real microstructures reconstructed with FIB-SEM are shown for comparison. The proposed GAN algorithm produces realistic microstructures, which indicates that GAN has a great potential to enable fast evaluation of various samples without carrying out complex FIB-SEM measurements.1. Gayon-Lombardo, L. Mosser, N. P. Brandon, and S. J. Cooper, npj Comput. Mater., 6, 1–11 (2020).2. Komatsu, A. Sciazko, and N. Shikazono, J. Power Sources, 485, 229317 (2021). Figure 1

Constrained realizations of 2MRS density and peculiar velocity fields: growth rate and local flow

ABSTRACT We generate constrained realizations (CRs) of the density and peculiar velocity fields within $200 \, h^{-1} \, \mathrm{Mpc}$ from the final release of the Two-Micron All-Sky Redshift Survey (2MRS) – the densest all-sky redshift survey to date. The CRs are generated by combining a Wiener filter estimator in spherical Fourier-Bessel space with random realizations of log-normally distributed density fields and Poisson-sampled galaxy positions. The algorithm is tested and calibrated on a set of semi-analytic mock catalogues mimicking the environment of the Local Group (LG), to rigorously account for the statistical and systematic errors of the reconstruction method. By comparing our peculiar velocity CRs with the observed velocities from the Cosmicflows-3 catalogue, we constrain the normalized linear growth rate to $f \sigma _8^{\text{lin}}= 0.367 \pm 0.060$, which is consistent at the 1.1σ level with the latest Planck results as well as other direct probes. Simultaneously, we estimate a bulk flow contribution from sources beyond the 2MRS reconstruction volume of $B^{\text{ext}}= 199 \pm 68 \, \mathrm{km} \, \mathrm{s}^{-1}$ towards l = 299 ± 18°, b = 8 ± 19°. The total reconstructed velocity field at the position of the LG, smoothed with a $1 \, h^{-1} \, \mathrm{Mpc}$ Gaussian, is $685 \pm 75 \, \mathrm{km} \, \mathrm{s}^{-1}$ towards l = 270.6 ± 6.6°, b = 35.5 ± 7.2°, in good agreement with the observed CMB dipole. The total reconstructed bulk flow within different radii is compatible with other measurements. Within a $50 \, h^{-1} \, \mathrm{Mpc}$ Gaussian window we find a bulk flow of $274 \pm 50 \, \mathrm{km} \, \mathrm{s}^{-1}$ towards l = 287 ± 9°, b = 11 ± 10°. The code used to generate the CRs and obtain these results, dubbed coras, is made publicly available.

Efficient computation of backprojection arrays for 3D light field deconvolution.

Light field deconvolution allows three-dimensional investigations from a single snapshot recording of a plenoptic camera. It is based on a linear image formation model, and iterative volume reconstruction requires to define the backprojection of individual image pixels into object space. This is effectively a reversal of the point spread function (PSF), and backprojection arrays H' can be derived from the shift-variant PSFs H of the optical system, which is a very time consuming step for high resolution cameras. This paper illustrates the common structure of backprojection arrays and the significance of their efficient computation. A new algorithm is presented to determine H' from H, which is based on the distinct relation of the elements' positions within the two multi-dimensional arrays. It permits a pure array rearrangement, and while results are identical to those from published codes, computation times are drastically reduced. This is shown by benchmarking the new method using various sample PSF arrays against existing algorithms. The paper is complemented by practical hints for the experimental acquisition of light field PSFs in a photographic setup.

Spatio-temporal performance in an incoherent holography lattice light-sheet microscope (IHLLS).

We propose an Incoherent holography detection technique for lattice light-sheet (IHLLS) systems for 3D imaging without moving either the sample stage or the detection microscope objective, providing intrinsic instrumental simplicity and high accuracy when compared to the original LLS schemes. The approach is based on a modified dual-lens Fresnel Incoherent Correlation Holography technique to produce a complex hologram and to provide the focal distance needed for the hologram reconstruction. We report such an IHLLS microscope, including characterization of the sensor performance, and demonstrate a significant contrast improvement on beads and neuronal structures within a biological test sample as well as quantitative phase imaging. The IHLLS has similar or better transverse performances when compared to the LLS technique. In addition, the IHLLS allows for volume reconstruction from fewer z-galvo displacements, thus facilitating faster volume acquisition.

Low annual hospital volume of anterior cruciate ligament reconstruction is not associated with higher revision rates.

Surgery performed in low-volume centres has been associated with longer operating time, longer hospital stays, lower functional outcomes, and higher rates of revision surgery, complications and mortality. This has been reported consistently in the arthroplasty literature, but there is a paucity of data regarding the relationship between surgical volume and outcome following anterior cruciate ligament (ACL) reconstruction. The purpose was to compare ACL reconstruction failure rates between hospitals performing different annual surgical volumes. All patients from the Norwegian Knee Ligament Register having primary autograft ACL reconstruction between 2004 and 2016 were included. Hospital volume was divided into quintiles based on the number of ACL reconstructions performed annually, defined arbitrarily as: 1-12 (V1), 13-24 (V2), 25-49 (V3), 50-99 (V4) and ≥ 100 (V5) annual procedures. Kaplan-Meier estimated survival curves and survival percentages were calculated with revision ACL reconstruction as the end point. Secondary outcome measures included (1) mean change in Knee Injury and Osteoarthritis Outcome Score (KOOS) Quality of Life (QoL) and Sport subsections from pre-operative to 5-year follow-up and (2) subjective failure defined as KOOS QoL < 44. Twenty thousand eight hundred and fifty patients met the inclusion criteria and 1195 (5.7%) underwent subsequent revision ACL reconstruction over the study period. Revision rates were lower in the lower volume hospitals compared with the higher volume hospitals (p < 0.001). There was no clinically significant difference in improvement between pre-operative and 5-year follow-up KOOS scores between hospital volume categories, but a higher proportion of patients having surgery at lower volume hospitals reported a subjective failure. Patients in the lower volume categories (V1-3) were more often male and older compared to the higher volume hospitals (V4-5). Concomitant meniscal injuries and participation in pivoting sports were most common in V5 compared with V1 (p < 0.001). Median operative time decreased as hospital volume increased, ranging from 90min at V1 hospitals to 56min at V5 hospitals (p < 0.001). Patients having ACL reconstruction at lower volume hospitals had a lower rate of subsequent revision surgery relative to higher volume hospitals. However, complications occurred more frequently, operative duration was longer, and the number of patients reporting a subjective failure of ACL reconstruction was highest at these lower volume hospitals. Level III.

An automatic multi-tissue human fetal brain segmentation benchmark using the Fetal Tissue Annotation Dataset

It is critical to quantitatively analyse the developing human fetal brain in order to fully understand neurodevelopment in both normal fetuses and those with congenital disorders. To facilitate this analysis, automatic multi-tissue fetal brain segmentation algorithms are needed, which in turn requires open datasets of segmented fetal brains. Here we introduce a publicly available dataset of 50 manually segmented pathological and non-pathological fetal magnetic resonance brain volume reconstructions across a range of gestational ages (20 to 33 weeks) into 7 different tissue categories (external cerebrospinal fluid, grey matter, white matter, ventricles, cerebellum, deep grey matter, brainstem/spinal cord). In addition, we quantitatively evaluate the accuracy of several automatic multi-tissue segmentation algorithms of the developing human fetal brain. Four research groups participated, submitting a total of 10 algorithms, demonstrating the benefits the dataset for the development of automatic algorithms.

Effect of Change of Kilovoltage and Voxel Size on 3D Volume Measurement Using Cone Beam Computed Tomography

Purpose: The aim of this study is to study the impact of change in kilovoltage (KV) or voxel size on extracted 3D radiographic volume measurement of different sizes of endodontic files and to determine the optimal exposure parameters for volume measurement in CBCT. Methods: Eight different endodontic k files were radiographically exposed at three different kilovoltages using CBCT and divided into three groups, group 1 (80 KV ), group 2 (60 KV ), and group 3 (50 KV ), then exposed to two different voxel sizes, and divided into two groups, group a (300 μm) and group b (180 μm). The 3D radiographic volume and the actual files volumes were measured using ITK-SNAP software and water displacement method respectively. Finding: Regarding changes in the kilovoltages, no significant difference ( p ˃0.05 ) was reported between the mean of the 3D radiographic volume of groups 3 and 2 with the mean of actual volume with a mean difference of 1.1 ±7.7 mm3 and 2.6 ±9.6 mm3 respectively. The results for voxel size change, showed no significant difference between the mean of the 3D radiographic volume of group (b) and actual volume group with a mean difference of 1.9 ±7.8 mm3. In the other hand, the difference between the mean of volume measurement at group (a) and actual group became significant with a mean difference of 10.5 ±5.7 mm3 was found. Conclusion: it concluded that both changes in kilovoltage and voxel size parameters affect significantly the 3D volume measurement and reconstruction.

Correlation analysis of resected breast tissue and implant volume after mastectomy and its association with breast density

BackgroundThe current methods for calculating the ideal implant volume for breast reconstruction are based on pre- or intraoperative volume measurements of the existing breast volume and do not take into account the individual breast density of the woman. This study aims is to identify objective parameters that can help to improve the optimal implant selection.Materials and methodsThis retrospective analysis includes 198 breast cancer patients who underwent mastectomy. Breast densities (ACR) measured in mammography and MRI were compared with the removed breast tissue weight and volume of the implants used. In addition, the resected weight was compared directly with the implant volume to calculate a mathematical function.ResultsThere was no significant correlation between the ACR values and the resected weights [correlation coefficient: mammography:− 0.117 (p = 0.176), MRI − 0.033 (p = 0.756)]. A negative correlation between the implant volumes and both imaging methods could be demonstrated [correlation coefficient: mammography − 0.268; p = 0.002; MRI was − 0.200 (p = 0.055)]. A highly significant correlation between the resected weights and the implant volumes (correlation coefficient 0.744; p < 0.001) was observed. This correlation corresponds to a power function (y = 34.71 x0.39), in which any resected weight can be used for the variable x to calculate the implant volume.ConclusionWe were able to show that there is a significant correlation between the resected breast tissue and the implant volume. With our novel potency function, the appropriate implant volume can be calculated for any resected weight making it easier for the surgeon to choose a fitting implant in a simple and more objective manner.

Rock physical and chemical alterations during the in-situ interaction between fracturing fluid and Silurian organic-rich shales in China

Hydraulic fracturing has been proved to be an effective way to unlock shale gas resources. During this process, fracturing fluid comes into contact with shale reservoirs and interact with the rocks. This could cause alteration of the pore systems in shales, thereby affecting gas transport and production. To illustrate this geochemical process and identify the physical and chemical alterations of shales, fluid-shale interaction at in-situ conditions is studied for typical marine organic-rich shales from the Silurian Longmaxi Formation in the Sichuan Basin, using actual fracturing fluid and deionized water over a 5-day period. The minerals and pore structures before and after the reaction were examined by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), QEMSCAN, computed tomography (CT) scanning, nitrogen adsorption testing and organic geochemical analysis. Results showed that, the fracturing fluid and deionized water caused indiscernible changes to the organic matter, but a variety of alterations on carbonate minerals. Calcites and dolomites were markedly dissolved, but quartzs, albites and illites remained relatively unaltered. More dolomites crystals were precipitated in the deionized water-shale interaction than in the fracturing fluid-shale interaction, and some of the fractures seemed to be filled by flocculation of friction reducers or deposited mineral particles. The fracturing fluid could enlarge the pore volumes and improve pore connectivity, and the invasion depth of fracturing fluid after 120 h’ was around 60 μm. The dissolved pores and loosening/shedding of particles detected by CT increased through time, and the calculated 3D pore volume increased by 67% at 24 h, 117% at 72 h, and 430% at 120 h compared to that of the initial sample. The XRD and nitrogen adsorption data indicated that new pore volumes increased with higher contents of carbonate minerals in the sample and longer treatment by fracturing fluid. The mineral and pore-scale alterations of shale reservoirs indicated that fracturing fluid-shale interaction (FFSI) enlarged the reservoir reconstruction volume, increased well performance during shut-in period and should be considered as part of the well treatment optimization process.

Three dimensional reconstruction of coronary artery stents from optical coherence tomography: experimental validation and clinical feasibility

The structural morphology of coronary stents (e.g. stent expansion, lumen scaffolding, strut apposition, tissue protrusion, side branch jailing, strut fracture), and the local hemodynamic environment after stent deployment are key determinants of procedural success and subsequent clinical outcomes. High-resolution intracoronary imaging has the potential to enable the geometrically accurate three-dimensional (3D) reconstruction of coronary stents. The aim of this work was to present a novel algorithm for 3D stent reconstruction of coronary artery stents based on optical coherence tomography (OCT) and angiography, and test experimentally its accuracy, reproducibility, clinical feasibility, and ability to perform computational fluid dynamics (CFD) studies. Our method has the following steps: 3D lumen reconstruction based on OCT and angiography, stent strut segmentation in OCT images, packaging, rotation and straightening of the segmented struts, planar unrolling of the segmented struts, planar stent wireframe reconstruction, rolling back of the planar stent wireframe to the 3D reconstructed lumen, and final stent volume reconstruction. We tested the accuracy and reproducibility of our method in stented patient-specific silicone models using micro-computed tomography (μCT) and stereoscopy as references. The clinical feasibility and CFD studies were performed in clinically stented coronary bifurcations. The experimental and clinical studies showed that our algorithm (1) can reproduce the complex spatial stent configuration with high precision and reproducibility, (2) is feasible in 3D reconstructing stents deployed in bifurcations, and (3) enables CFD studies to assess the local hemodynamic environment within the stent. Notably, the high accuracy of our algorithm was consistent across different stent designs and diameters. Our method coupled with patient-specific CFD studies can lay the ground for optimization of stenting procedures, patient-specific computational stenting simulations, and research and development of new stent scaffolds and stenting techniques.

Droplet size distributions in cryogenic flash atomization

Flash atomization can occur in rocket thrusters operated at near vaccum conditions just prior to ignition when cryogenic propellants are injected into the reaction chamber. Although the morphology of flashing sprays has been widely studied, empirical observations of the primary breakup mechanisms at the micro-scale are currently not feasible. Still, further analysis of the micro-scales is necessary for development of closure models in both empirical and numerical models. In this work direct numerical simulations are performed to provide insight into the microscopic processes that dominate the dynamics of the primary atomization. We use a multiphase solver (FS3D) based on the volume of fluid method and PLIC reconstruction to track the liquid-vapour interface with high fidelity, fully resolving viscous and capillary effects. Thermodynamic effects are introduced by calibration of the fluid properties and evaporation rate to a target range of thermodynamic conditions and nuclei number density. The use of an affordable incompressible scheme allows for highly resolved simulations comprising up to thousand bubbles across a range of Weber and Ohnesorge numbers. Using a randomized bubble arrangement it is generally observed that the qualitative characterization of the breakup dynamics corroborates previous results using regular bubble arrays. However, these differ substantially from the simplified mechanics hypothesised in the literature. A temporal analysis of the breakup provides estimates for the rate of change in the spray surface area and volume fraction. The droplet size distributions are compared in terms of droplet number, surface area and volume fraction. A model based on the thermodynamic conditions is proposed to estimate the SMD for different Weber numbers.

Single-objective selective-volume illumination microscopy enables high-contrast light-field imaging.

The performance of light-field microscopy is improved by selectively illuminating the relevant subvolume of the specimen with a second objective lens. Here we advance this approach to a single-objective geometry, using an oblique one-photon illumination path or two-photon illumination to accomplish selective-volume excitation. The elimination of the second orthogonally oriented objective to selectively excite the volume of interest simplifies specimen mounting; yet, this single-objective approach still reduces the out-of-volume background, resulting in improvements in image contrast, effective resolution, and volume reconstruction quality. We validate our new, to the best of our knowledge, approach through imaging live developing zebrafish, demonstrating the technology's ability to capture imaging data from large volumes synchronously with high contrast while remaining compatible with standard microscope sample mounting.

AFRL Additive Manufacturing Modeling Series: Challenge 4, 3D Reconstruction of an IN625 High-Energy Diffraction Microscopy Sample Using Multi-modal Serial Sectioning

High-energy diffraction microscopy (HEDM) in-situ mechanical testing experiments offer unique insight into the evolving deformation state within polycrystalline materials. These experiments rely on a sophisticated analysis of the diffraction data to instantiate a 3D reconstruction of grains and other microstructural features associated with the test volume. For microstructures of engineering alloys that are highly twinned and contain numerous features around the estimated spatial resolution of HEDM reconstructions, the accuracy of the reconstructed microstructure is not known. In this study, we address this uncertainty by characterizing the same HEDM sample volume using destructive serial sectioning (SS) that has higher spatial resolution. The SS experiment was performed on an Inconel 625 alloy sample that had undergone HEDM in-situ mechanical testing to a small amount of plastic strain (~ 0.7%), which was part of the Air Force Research Laboratory Additive Manufacturing (AM) Modeling Series. A custom-built automated multi-modal SS system was used to characterize the entire test volume, with a spatial resolution of approximately 1 µm. Epi-illumination optical microscopy images, backscattered electron images, and electron backscattered diffraction maps were collected on every section. All three data modes were utilized and custom data fusion protocols were developed for 3D reconstruction of the test volume. The grain data were homogenized and downsampled to 2 µm as input for Challenge 4 of the AM Modeling Series, which is available at the Materials Data Facility repository.

Evaluation of the Accuracy of Standardized Uptake Values of 18F-fluorodeoxyglucose in Lung Lesions Based on Phantom Studies.

The aim of the study was to estimate the accuracy of standardized uptake values of 18F-fluorodeoxyglucose (18F-FDG) in lung lesions during positron emission tomography combined with computed tomography (PET/CT) imaging, based on phantom studies performed for different PET/CT scanners.Materials and MethodsThe analysis of the PET/CT with 18F-FDG data was performed for 86 patients newly diagnosed with the lung lesions: malignant tumors (n=37), benign tumors and inflammatory diseases (n=49). The criteria for inclusion in the study were developed considering the recommendations of the Fleischner Society (2017). The characteristics of the lesions on CT met the following requirements: a round shape or close to it; total size of 8 to 30 mm; solid or subsolid structure (with the exception of lesion with ground-glass opacity); a solid part size of ≥8 mm. All the patients had no signs of pleurisy, lymphadenopathy, or cancer history. PET/CT imaging with 18F-FDG was performed with three scanners: Discovery 690 (General Electric, USA), Biograph mCT 128 (Siemens, Germany), and Biograph mCT 40 (Siemens); the preparation of patients prior to the scan was standardized. To determine the reference accumulation of a radiopharmaceutical in the pathological lesion, four scans of a specialized NEMA IEC PET Body Phantom Set (USA) were performed for each scanner. For each unit, the recovery coefficients (RCs) of radioactivity, maximum and recovered (corrected) standardized uptake values (SUVs) were determined. Statistical relationship between the size of lesions, SUVmax and SUVcorrect was evaluated. Data processing was performed using MedCalc v. 19.2.0 software.ResultsDuring the phantom study, the underestimation of the radioactivity was determined in the spheres with the diameters of 10 and 13 mm, overestimation was observed in the sphere with the diameter of 28 mm. Both underestimation and overestimation of radioactivity were determined for the spheres with a diameter of 17 and 22 mm.SUVmax differed from the reference values for 85 patients (98.8%). The underestimation of these values was found for 63 patients (73.2%) due to the partial volume effect. The greatest underestimation was observed for the patients with 8 mm diameter lesions. Depending on the scanner, the underestimation of the SUVmax in these patients reached up to 54–73%. For 9 patients (25%) with malignant tumors of 9–12 mm, the utility of RC made it possible to avoid false negative results. For the lesions with a diameter of 30 mm, an overestimation of SUVmax up to 22% was determined due to the negative influence of the reconstruction algorithms.ConclusionThe use of RC eliminates the influence of the partial volume effect and reconstruction methods on the accuracy of estimating the SUVmax in lung lesions, which ensures reproducibility, increase in the information content of the method, as well as the comparability of the results of PET/CT with 18F-FDG obtained on the different models of PET/CT units with different technological characteristics.

Preoperative Staging Diagnosis of Colorectal Cancer Based on Multi-Row Spiral CT

Colorectal cancer is a common malignant tumor of digestive tract, and its incidence has increased significantly in recent years. The 5-year survival rate of patients with early local colorectal cancer is more than 90%, with local invasion of about 68%, and distant metastasis of less than 10%. Therefore, early diagnosis and early treatment is an effective means for the prevention and treatment of colorectal cancer. At present, X-ray air-barium double contrast radiography and fiberoptic endoscope are most commonly used in the examination of colorectal tumors in the world. These two methods have the advantages of simple operation, intuition and low cost. However, it is limited to judge the depth of tumor invasion, whether to break through the serosa, lymphatic metastasis, and distant metastasis. In this work, it can be confirmed that the measurement of preoperative tumor vascular volume reconstruction density is feasible in the preoperative evaluation of colorectal cancer, it will provide clinicians with more valuable information about preoperative tumor staging. Besides, multi-slice spiral CT has the advantages of less trauma, high speed, and clear image. It can not only judge the location of the tumor, the depth, and extent of tumor invasion, and show distant organ metastasis, but also has good application value in tumor staging. In this paper, the clinical data and MSCT imaging data of patients with colorectal cancer were analyzed retrospectively, and the value of MSCT in the diagnosis of colorectal cancer was discussed.

Studi Interaksi Materi Elektron Al2O3 dengan Simulasi Monte Carlo dan wet-STEM Electron Tomography

Materials science and biology are both fields that require a three-dimensional (3D) structure characterization method. Tomography is an efficient tool for analyzing the three-dimensional structure of a material. The principle is based on the acquisition of a series of projected images at different tilt angles, and on the calculation of the three-dimensional (3D) volume reconstruction (tomogram) using a special algorithm. Various studies have been developed to perform electron tomography in Environmental Scanning Electron Microscopy (ESEM), which provides access to the observation of hydrated samples in an aquatic environment. In this study we present the feasibility of tomography on wet materials, namely Al2O3 compounds by simulating electron material interactions. From these simulations, we determine the optimum detectable thickness of water in the wet material which is calculated by Monte Carlo simulation. Keyword : Al 2 O 3, Tomography, Monte Carlo Simulation, wet-STEM

Fast fully automatic detection, classification and 3D reconstruction of pulmonary nodules in CT images by local image feature analysis

This study develops a computer-aided diagnosis (CAD) system for automatic detection and classification of pulmonary nodules in lung computed tomography (CT) images, which can simultaneously detect and classify ground-glass opacity (GGO), part-solid, and solid nodules. From the morphological feature and local image features of pulmonary nodules, a total of ten features were selected for artificial neural network (ANN) training and testing, to ensure the system can detect and classify pulmonary nodules. Then, the cross-sectional area of each slice of pulmonary nodule was extracted. The response evaluation criteria in solid tumor (RECIST) value was obtained using the Euclidean distance formula, and the number of pixels of the maximum cross-sectional area was counted for area computation. The nodule volume and 3D reconstruction was obtained using the marching cube algorithm and Riemann integral formula. The sensitivity of system detection and classification were 93.13% and 92.70%, respectively. The proposed system can detect GGO, part-solid, and solid nodules, and takes only 0.1 s to process a single image. This study used the clay model imitating pulmonary nodule morphology as physical samples. Each physical sample underwent three CT. The average difference between the physical volume and the volume derived from this study was 0.37%. The detection and classification results of the system enhanced the clinical detection of missing nodules. 3D reconstruction and volume information of the nodules can give their volume doubling time and growth rate when the patient undergoes CT for the second time, thus enhancing the effect of diagnosis and treatment.

Performance Enhanced Ultrasound Probe Tracking With a Hemispherical Marker Rigid Body.

Among tracking techniques applied in the 3-D freehand ultrasound (US), the camera-based tracking method is relatively mature and reliable. However, constrained by manufactured marker rigid bodies, the US probe is usually limited to operate within a narrow rotational range before occlusion issues affect accurate and robust tracking performance. Thus, this study proposed a hemispherical marker rigid body to hold passive noncoplanar markers so that the markers could be identified by the camera, mitigating self-occlusion. The enlarged rotational range provides greater freedom for sonographers while performing examinations. The single-axis rotational and translational tracking performances of the system, equipped with the newly designed marker rigid body, were investigated and evaluated. Tracking with the designed marker rigid body achieved high tracking accuracy with 0.57° for the single-axis rotation and 0.01 mm for the single-axis translation for sensor distance between 1.5 and 2 m. In addition to maintaining high accuracy, the system also possessed an enhanced ability to capture over 99.76% of the motion data in the experiments. The results demonstrated that with the designed marker rigid body, the missing data were remarkably reduced from over 15% to less than 0.5%, which enables interpolation in the data postprocessing. An imaging test was further conducted, and the volume reconstruction of a four-month fetal phantom was demonstrated using the motion data obtained from the tracking system.