Quantification Of Volume Fraction Research Articles

Quantitative assessment of machine-learning segmentation of battery electrode materials for active material quantification

X-ray computed tomography (CT) is an important tool for studying battery electrode microstructures but relies on robust segmentation for validity. Here, several approaches to applying accessible machine-learning segmentation software to segment open-source lithium-ion battery (LIB) electrode tomograms are followed to identify the optimised methodology that minimises variation in active material volume fraction quantification across three users. Iterative, manual training across seven cross-sectional slices (<5%) of a tomogram is identified as an optimal balance between variance and user interaction, where 10–25% of each slice was trained. This approach is applied to lab-based X-ray CT data and compared with data obtained by focused-ion beam/scanning electron microscopy slice-and-view tomography. Variation in active material volume fraction between users is lower for at least one of these two approaches (10% or 25%) when applied to raw LIB cathode tomograms, versus unsupervised techniques such as simple and watershed segmentations. On average, the absolute volume fraction values are closer to that acquired by the correlated technique, most closely matching for high-resolution data. The present analysis provides an optimised approach for using open-source software to apply machine-learning segmentation when quantifying active material volume fractions in cutting-edge LIB electrodes, providing a more robust route to active material quantification.

Detection of extracellular myocardial matrix with Dual Energy computed tomography: systematic review and meta-analysis

Background. The amount of extracellular myocardial matrix is a non-invasive tool for quantitative assessment of myocardial fibrosis. MRI with late gadolinium-enhancement is considered to be the “Gold standard” of non-invasive practice. Dual Energy computed tomography is a new non-invasive approach for detection of myocardial fibrosis and its prognostic value remains unclear. The purpose of this study was to summarize all available data and to study prognostic value of DECT for the detection of fibrotic changes in myocardium.Methods. We searched MEDLINE, EMBASE, Cochrane, SCOPUS and Web of Science for cohort studies up to October 2021 that reported myocardial extracellular volume fraction quantification using contrast enhanced dual energy CT or/and MRI with delayed enhancement.Results. Eleven studies met eligibility criteria. A systematic analysis demonstrated the difference in extracellular volume fraction in patients with fibrotic and inflammation changes of the myocardium, as well as good comparability between DECT and MRI. The value of extracellular volume fraction in myocardium with fibrotic or inflammatory changes was higher than in healthy tissue, which makes it possible to use the ECV as a non-invasive marker of myocardial fibrosis.

Myocardial extracellular volume fraction quantification based on T1 mapping at 3 T: quality optimization by contour-based registration and segmental analysis.

Myocardial extracellular volume fraction (ECV) assessment can be affected by various technical and subject-related factors. To evaluate the role of contour-based registration in quantification of ECV and investigate normal segment-based myocardial ECV values at 3T. Pre- and post-contrast T1 mapping images of the left ventricular basal, mid-cavity, and apical slices were obtained in 26 healthy volunteers. ECV maps were generated using motion correction with and without contour-based registration. The image quality of all ECV maps was evaluated by a 4-point scale. Slices were dichotomized according to the occurrence of misregistration in the source data. Contour-registered ECVs and standard ECVs were compared within each subgroup using analysis of variance for repeated measurements and generalized linear mixed models. In all three slices, higher quality of ECV maps were found using contour-registered method than using standard method. Standard ECVs were statistically different from contour-registered ECVs in global (26.8% ± 2.8% vs. 25.8% ± 2.4%; P = 0.001), mid-cavity (25.4% ± 3.1% vs. 24.3% ± 2.5%; P = 0.016), and apical slices (28.7% ± 4.1% vs. 27.2% ± 3.4%; P = 0.010). In the misregistration subgroups, contour-registered ECVs were lower with smaller SDs (basal: 25.2% ± 1.8% vs. 26.7% ± 2.6%; P = 0.038; mid-cavity: 24.4% ± 2.3% vs. 26.8% ± 3.1%; P = 0.012; apical: 27.5% ± 3.6% vs. 29.7% ± 4.5%; P = 0.016). Apical (27.2% ± 3.4%) and basal-septal ECVs (25.6% ± 2.6%) were statistically higher than mid-cavity ECV (24.3% ± 2.5%; both P < 0.001). Contour-based registration can optimize image quality and improve the precision of ECV quantification in cases demonstrating ventricular misregistration among source images.

Microstructural and crystallographic characterization of 455 MPa sour service plates with low Mn high temperature processed alloy concept and its association with drop weight tear test performance

The aim of this study was to analyze the mechanical properties of a X65 low Mn and high Nb steel for sour service application, particularly the drop-weight-tear test (DWTT) performance in order to establish correlation with the microstructural and crystallographic features of a steel with complex microstructure. Samples were analyzed at 55%, 65% and 75% of deformation during the finishing stage of rolling. The characterization of the samples involved electron backscatter diffraction (EBSD) technique for the determination and volume fraction quantification of the microconstituents and crystallographic texture analyses. The results showed that the plate with 55% of deformation displayed the lowest level of strength and the lowest DWTT shear area, while the plate with 65% of deformation exhibited the highest strength and DWTT toughness levels. EBSD results indicated that the plate produced with 65% of deformation had the largest dislocation density among all three samples and showed the highest intensity of the texture components concentrated along the α-fiber, particularly in the vicinity of the {113}<110> and {112}<110> components, responsible for activating ductile fracture, while samples 55% and 75% had a broader spread towards {001}<110>, and an overall higher intensity of the rotated cube components that favor cleavage fracture. For the plate with 75% of deformation, the mean flow stress (MFS) result suggested that partial recrystallization occurred during the finishing stage of hot rolling which was also proved by EBSD.These findings have proven that low Mn steels processed at high temperatures have a crucial dependency on Nb for the development of deformation textures that will help sustain high levels of fracture toughness, particularly when dealing with heavy plates for offshore applications. It has been observed that this steel concept is inclined to experience loss of toughness due to the softening of austenite during the finishing stage of rolling, even though the temperatures were below the no-recrystallization temperature, and a proper rolling schedule must be selected to mitigate this effect.The overall results showed that a rolling scheduled aiming at increasing the volume fraction of acicular ferrite and reducing the polygonal ferrite together with a higher level of strain and crystallographic texture consisting of high intensity deformation components, will result in a better combination of strength and toughness.

Myocardial extracellular volume fraction quantification in an animal model of the doxorubicin-induced myocardial fibrosis: a synthetic hematocrit method using 3T cardiac magnetic resonance.

Visualization of diffuse myocardial fibrosis is challenging and mainly relies on histology. Cardiac magnetic resonance (CMR), which uses extracellular contrast agents, is a rapidly developing technique for measuring the extracellular volume (ECV). The objective of this study was to evaluate the feasibility of the synthetic myocardial ECV fraction based on 3.0 T CMR compared with the conventional ECV fraction. This study was approved by the local animal care and ethics committee. Fifteen beagle models with diffuse myocardial fibrosis, including 12 experimental and three control subjects, were generated by injecting doxorubicin 30 mg/m2 intravenously every three weeks for 24 weeks. Short-axis (SAX) and 4-chamber long-axis (LAX) T1 maps were acquired for both groups. The association between hematocrit (Hct) and native T1blood was derived from 9 non-contrast CMR T1 maps of 3 control beagles using regression analysis. Synthetic ECV was then calculated using the synthetic Hct and compared with conventional ECV at baseline and the 16th and 24th week after doxorubicin administration. The collagen volume fraction (CVF) value was measured on digital biopsy samples. Bland-Altman plots were used to analyze the agreement between conventional and synthetic ECV. Correlation analyses were performed to explore the association among conventional ECV, synthetic ECV, CVF, and left ventricular ejection fraction (LVEF). The regression model synthetic Hct = 816.46*R1blood - 0.01 (R2=0.617; P=0.012) was used to predict the Hct from native T1blood values. The conventional and synthetic ECV fractions of experimental animals at the 16th and 24th week after modeling were significantly higher than those measured at the baseline (31.4%±2.2% and 36.3%±2.1% vs. 22.9%±1.7%; 29.9%±2.4% and 36.1%±2.6% vs. 22.0%±2.4%; all with P<0.05). Bland-Altman plots showed a bias (1.0%) between conventional and synthetic ECV with 95% limits of agreement of -2.5% to 4.4% in the per-subject analysis (n=21) and a bias (1.0%) between conventional and synthetic ECV with 95% limits of agreement of -2.4% to 4.3% in the per-segment analysis (n=294). Conventional and synthetic ECV were well correlated with CVF (r=0.937 and 0.925, all with P<0.001, n=10). Our study showed promising results for using synthetic ECV compared with the conventional ECV for providing accurate quantification of myocardial ECV without the need for blood sampling.

Investigation of a Monturaqui Impactite by Means of Bi-Modal X-ray and Neutron Tomography

X-ray and neutron tomography are applied as a bi-modal approach for the 3D characterisation of a Monturaqui impactite formed by shock metamorphism during the impact of an iron meteorite with the target rocks in the Monturaqui crater (Chile). The particular impactite exhibits structural heterogeneities on many length scales: its composition is dominated by silicate-based glassy and crystalline materials with voids and Fe/Ni-metal and oxihydroxides particles generally smaller than 1 mm in diameter. The non-destructive investigation allowed us to apply a novel bi-modal imaging approach that provides a more detailed and quantitative understanding of the structural and chemical composition compared to standard single mode imaging methods, as X-ray and neutron interaction with matter results in different attenuation coefficients with a non-linear relation. The X-ray and neutron data sets have been registered, and used for material segmentation, porosity and metallic content characterization. The bimodal data enabled the segmentation of a large number of different materials, their morphology as well as distribution in the specimen including the quantification of volume fractions. The 3D data revealed an evaporite type of material in the impactite not noticed in previous studies. The present study is exemplary in demonstrating the potential for non-destructive characterisation of key features of complex multi-phase objects such as impactites.

Validation of Blood Volume Fraction Quantification with 3D Gradient Echo Dynamic Contrast-Enhanced Magnetic Resonance Imaging in Porcine Skeletal Muscle.

The purpose of this study was to assess the accuracy of fractional blood volume (vb) estimates in low-perfused and low-vascularized tissue using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The results of different MRI methods were compared with histology to evaluate the accuracy of these methods under clinical conditions. vb was estimated by DCE-MRI using a 3D gradient echo sequence with k-space undersampling in five muscle groups in the hind leg of 9 female pigs. Two gadolinium-based contrast agents (CA) were used: a rapidly extravasating, extracellular, gadolinium-based, low-molecular-weight contrast agent (LMCA, gadoterate meglumine) and an extracellular, gadolinium-based, albumin-binding, slowly extravasating blood pool contrast agent (BPCA, gadofosveset trisodium). LMCA data were evaluated using the extended Tofts model (ETM) and the two-compartment exchange model (2CXM). The images acquired with administration of the BPCA were used to evaluate the accuracy of vb estimation with a bolus deconvolution technique (BD) and a method we call equilibrium MRI (EqMRI). The latter calculates the ratio of the magnitude of the relaxation rate change in the tissue curve at an approximate equilibrium state to the height of the same area of the arterial input function (AIF). Immunohistochemical staining with isolectin was used to label endothelium. A light microscope was used to estimate the fractional vascular area by relating the vascular region to the total tissue region (immunohistochemical vessel staining, IHVS). In addition, the percentage fraction of vascular volume was determined by multiplying the microvascular density (MVD) with the average estimated capillary lumen, , where d = 8μm is the assumed capillary diameter (microvascular density estimation, MVDE). Except for ETM values, highly significant correlations were found between most of the MRI methods investigated. In the cranial thigh, for example, the vb medians (interquartile range, IQRs) of IHVS, MVDE, BD, EqMRI, 2CXM and ETM were vb = 0.7(0.3)%, 1.1(0.4)%, 1.1(0.4)%, 1.4(0.3)%, 1.2(1.8)% and 0.1(0.2)%, respectively. Variances, expressed by the difference between third and first quartiles (IQR) were highest for the 2CXM for all muscle groups. High correlations between the values in four muscle groups—medial, cranial, lateral thigh and lower leg - estimated with MRI and histology were found between BD and EqMRI, MVDE and 2CXM and IHVS and ETM. Except for the ETM, no significant differences between the vb medians of all MRI methods were revealed with the Wilcoxon rank sum test. The same holds for all muscle regions using the 2CXM and MVDE. Except for cranial thigh muscle, no significant difference was found between EqMRI and MVDE. And except for the cranial thigh and the lower leg muscle, there was also no significant difference between the vb medians of BD and MVDE. Overall, there was good vb agreement between histology and the BPCA MRI methods and the 2CXM LMCA approach with the exception of the ETM method. Although LMCA models have the advantage of providing excellent curve fits and can in principle determine more physiological parameters than BPCA methods, they yield more inaccurate results.

Liver fat volume fraction quantification with fat and water T1 and T2* estimation and accounting for NMR multiple components in patients with chronic liver disease at 1.5 and 3.0 T

To validate a magnitude-based method for fat volume fraction (FVF) quantification in the liver without any dominant component ambiguity problems and with the aim of transferring this method to any imaging system (clinical fields of 1.5 and 3.0T). MR imaging was performed at 1.5 and 3.0T using a multiple-angle multiple-gradient echo sequence. A quantification algorithm correcting for relaxation time effects using a disjointed estimation of T1 and T2* of fat and water and accounting for the NMR spectrum of fat was developed. Validations were performed on fat-water emulsion at 1.5 and 3.0T and compared with (1)H-MRS. This was followed by a prospective in-vivo comparative study on 28 patients with chronic liver disease and included histology. Phantom study showed good agreement between MRI and MRS. MR-estimated FVF and histological results correlated strongly and FVF allowed the diagnosis of mild (cutoff = 5.5%) and moderate steatosis (cutoff = 15.2%) with a sensitivity/specificity of 100%. FVF calculation worked independently of the field strength. FVF may be a relevant biomarker for the clinical follow-up of patients (1) with or at risk of NAFLD (2) of steatosis in patients with other chronic liver diseases. • Non-invasive techniques to diagnose non-alcoholic fatty liver diseases (NAFLD) are important. • Liver fat volume fraction quantified using MRI correlates well with histology. • Fat volume fraction could be a relevant marker for NAFLD clinical follow-up. • Disjointed relaxation time estimation could potentially identify factors contributing to NAFLD.

Retained austenite stability investigation in TRIP steel using neutron diffraction

In situ neutron diffraction experiment was employed for monitoring of conditioned austenite transformation to ferrite, and also for the retained austenite stability evaluation during subsequent mechanical loading. The progress in the austenite decomposition to ferrite is monitored at different transformation temperatures. The relevant information on the course of the transformation is extracted from neutron diffraction spectra. The useful information was also obtained on the retained austenite stability in the TRIP steel during mechanical testing. The in situ neutron diffraction experiments were conducted at two different diffractometers to assess the reliability of the neutron diffraction technique at monitoring the transformation of the retained austenite during room temperature tensile testing. In both experiments the neutron investigation was focused on the volume fraction quantification of the retained austenite as well as on internal stresses rising in structure phases due to the retained austenite transformation.

In Situ Neutron Diffraction Analysis of Phase Transformation Kinetics in TRIP Steel

The precise characterization of the multiphase microstructure of low alloyed TRIP steels is of great importance for the interpretation and optimisation of their mechanical properties. In-situ neutron diffraction experiment was employed for monitoring of conditioned austenite transformation to ferrite, and also for retained austenite stability evaluation during subsequent mechanical loading. The progress in austenite decomposition to ferrite is monitored at different transformation temperatures. The relevant information on the course of transformation is extracted from neutron diffraction spectra. The integrated intensities of austenite and ferrite neutron diffraction profiles over the time of transformation are then assumed as a measure of the volume fractions of both phases in dependence on transformation temperature. Useful information was also obtained on retained austenite stability in TRIP steel during mechanical testing. The in-situ neutron diffraction experiments were conducted at two different diffractometers to assess the reliability of neutron diffraction technique in monitoring the transformation of retained austenite during room temperature tensile test. In both experiments the neutron investigation was focused on the volume fraction quantification of retained austenite as well as on internal stresses rising in structure phases due to retained austenite transformation.

Quantification of Volume Fraction of Precipitates in an Aged Al-1.0 mass%Mg&lt;SUB&gt;2&lt;/SUB&gt;Si Alloy

An Al-1.0 mass%Mg2Si alloy was aged at 473 K for 36 ks. Using the same sample, resistivity (ρ) measurements, tensile tests and TEM observations were carried out. The volume fraction (Vfρ) of precipitates was estimated from the decrement in resistivity due to aging. Length (λ), diameter (d) and number density (NP) per unit volume of the needle-shaped precipitates were measured on TEM micrographs. Perhaps because of initiation of overaging in the present aging condition, λ and NP showed a wide scatter and differed significantly in two equivalent samples, independently heat treated and tested. However, proof stress and Vfρ in the two runs well coincided with each other and the volume fraction estimated from TEM micrographs (Vf TEM) matched within a factor of 2 for the two runs.

Llo Phase Formation in CoPt Thin Films

ABSTRACTThe high magnetic anisotropy and high coercivity of equiatomic CoPt thin films make them attractive as potential materials for magnetic recording applications. Magnetic coercivity (Hc) over 10 kOe has been measured in films in which the as-deposited fee phase has been partially transformed to the atomically ordered Ll0 phase. Very high Hc has been related to high volume fraction and small size of the Ll0 precipitates. A better understanding of the Ll0 phase formation and quantification of volume fraction is critical to optimizing the magnetic properties of this material.As we have previously reported, an increase in Hc was observed with an increase in Ll0 volume fraction in 10 nm thick, equiatomic CoPt films. In our current investigation we have observed that, at anneal temperatures far from the order/disorder transition temperature, e.g. at T = 0.6 Tc, numerous, very fine Ll0 precipitates are seen, some of which cluster at the parent phase grain boundaries. At T = 0.85 Tc, very few, larger Ll0 regions were seen. As precipitates of the ordered phase grow to impingement, antiphase boundaries (APB) are formed. This is consistent with a heterogeneous nucleation and growth mechanism for the formation of the Ll0 phase throughout the temperature range studies.