114 research outputs found
Relational Modeling for Robust and Efficient Pulmonary Lobe Segmentation in CT Scans
Pulmonary lobe segmentation in computed tomography scans is essential for
regional assessment of pulmonary diseases. Recent works based on convolution
neural networks have achieved good performance for this task. However, they are
still limited in capturing structured relationships due to the nature of
convolution. The shape of the pulmonary lobes affect each other and their
borders relate to the appearance of other structures, such as vessels, airways,
and the pleural wall. We argue that such structural relationships play a
critical role in the accurate delineation of pulmonary lobes when the lungs are
affected by diseases such as COVID-19 or COPD.
In this paper, we propose a relational approach (RTSU-Net) that leverages
structured relationships by introducing a novel non-local neural network
module. The proposed module learns both visual and geometric relationships
among all convolution features to produce self-attention weights.
With a limited amount of training data available from COVID-19 subjects, we
initially train and validate RTSU-Net on a cohort of 5000 subjects from the
COPDGene study (4000 for training and 1000 for evaluation). Using models
pre-trained on COPDGene, we apply transfer learning to retrain and evaluate
RTSU-Net on 470 COVID-19 suspects (370 for retraining and 100 for evaluation).
Experimental results show that RTSU-Net outperforms three baselines and
performs robustly on cases with severe lung infection due to COVID-19
Correlations between stacked structures and weak itinerant magnetic properties of La Y Ni compounds
Hexagonal LaNi and rhombohedral YNi are weak itinerant
antiferromagnet (wAFM) and ferromagnet (wFM), respectively. The crystal
structure and magnetic properties of intermetallic compounds ( =
La, Y, = Ni) have been investigated combining X-ray powder diffraction and
magnetic measurements. The LaYNi intermetallic compounds with
crystallize in the CeNi-type hexagonal structure
with Y preferentially located in the [] units. The compounds with larger
Y content () crystallize in both hexagonal and rhombohedral
(GdCo-type) structures with a progressive substitution of Y for La in
the sites belonging to the [] units. YNi crystallizes in the
rhombohedral structure only. The average cell volume decreases linearly versus
Y content, whereas the c/a ratio presents a minimum at due to geometric
constrains. The magnetic properties are strongly dependent on the structure
type and the Y content. LaNi displays a complex metamagnetic behavior
with split AFM peaks. Compounds with x = 0.25 and 0.5 display a wAFM ground
state and two metamagnetic transitions, the first one towards an intermediate
wAFM state and the second one towards a FM state.T and the second critical
field increase with the Y content, indicating a stabilization of the AFM state.
LaYNi, which is as the boundary between the two structure types, presents a
very wFM state at low field and an AFM state as the applied field increases.
All the compounds with and containing a rhombohedral phase are wFM with
= 53(2) K. In addition to the experimental studies, first principles
calculations using spin polarization have been performed to interpret the
evolution of both structural phase stability and magnetic ordering for .Comment: 26 pages (7 for supplementary material), 4 tables, 9 main figures and
8 figures in supplementary materia
Emphysema subtyping on thoracic computed tomography scans using deep neural networks
Accurate identification of emphysema subtypes and severity is crucial for effective management of COPD and the study of disease heterogeneity. Manual analysis of emphysema subtypes and severity is laborious and subjective. To address this challenge, we present a deep learning-based approach for automating the Fleischner Society’s visual score system for emphysema subtyping and severity analysis. We trained and evaluated our algorithm using 9650 subjects from the COPDGene study. Our algorithm achieved the predictive accuracy at 52%, outperforming a previously published method’s accuracy of 45%. In addition, the agreement between the predicted scores of our method and the visual scores was good, where the previous method obtained only moderate agreement. Our approach employs a regression training strategy to generate categorical labels while simultaneously producing high-resolution localized activation maps for visualizing the network predictions. By leveraging these dense activation maps, our method possesses the capability to compute the percentage of emphysema involvement per lung in addition to categorical severity scores. Furthermore, the proposed method extends its predictive capabilities beyond centrilobular emphysema to include paraseptal emphysema subtypes.</p
Emphysema Subtyping on Thoracic Computed Tomography Scans using Deep Neural Networks
Accurate identification of emphysema subtypes and severity is crucial for
effective management of COPD and the study of disease heterogeneity. Manual
analysis of emphysema subtypes and severity is laborious and subjective. To
address this challenge, we present a deep learning-based approach for
automating the Fleischner Society's visual score system for emphysema subtyping
and severity analysis. We trained and evaluated our algorithm using 9650
subjects from the COPDGene study. Our algorithm achieved the predictive
accuracy at 52\%, outperforming a previously published method's accuracy of
45\%. In addition, the agreement between the predicted scores of our method and
the visual scores was good, where the previous method obtained only moderate
agreement. Our approach employs a regression training strategy to generate
categorical labels while simultaneously producing high-resolution localized
activation maps for visualizing the network predictions. By leveraging these
dense activation maps, our method possesses the capability to compute the
percentage of emphysema involvement per lung in addition to categorical
severity scores. Furthermore, the proposed method extends its predictive
capabilities beyond centrilobular emphysema to include paraseptal emphysema
subtypes
Emphysema subtyping on thoracic computed tomography scans using deep neural networks
Accurate identification of emphysema subtypes and severity is crucial for effective management of COPD and the study of disease heterogeneity. Manual analysis of emphysema subtypes and severity is laborious and subjective. To address this challenge, we present a deep learning-based approach for automating the Fleischner Society’s visual score system for emphysema subtyping and severity analysis. We trained and evaluated our algorithm using 9650 subjects from the COPDGene study. Our algorithm achieved the predictive accuracy at 52%, outperforming a previously published method’s accuracy of 45%. In addition, the agreement between the predicted scores of our method and the visual scores was good, where the previous method obtained only moderate agreement. Our approach employs a regression training strategy to generate categorical labels while simultaneously producing high-resolution localized activation maps for visualizing the network predictions. By leveraging these dense activation maps, our method possesses the capability to compute the percentage of emphysema involvement per lung in addition to categorical severity scores. Furthermore, the proposed method extends its predictive capabilities beyond centrilobular emphysema to include paraseptal emphysema subtypes.</p
Emphysema subtyping on thoracic computed tomography scans using deep neural networks
Accurate identification of emphysema subtypes and severity is crucial for effective management of COPD and the study of disease heterogeneity. Manual analysis of emphysema subtypes and severity is laborious and subjective. To address this challenge, we present a deep learning-based approach for automating the Fleischner Society’s visual score system for emphysema subtyping and severity analysis. We trained and evaluated our algorithm using 9650 subjects from the COPDGene study. Our algorithm achieved the predictive accuracy at 52%, outperforming a previously published method’s accuracy of 45%. In addition, the agreement between the predicted scores of our method and the visual scores was good, where the previous method obtained only moderate agreement. Our approach employs a regression training strategy to generate categorical labels while simultaneously producing high-resolution localized activation maps for visualizing the network predictions. By leveraging these dense activation maps, our method possesses the capability to compute the percentage of emphysema involvement per lung in addition to categorical severity scores. Furthermore, the proposed method extends its predictive capabilities beyond centrilobular emphysema to include paraseptal emphysema subtypes.</p
Emphysema subtyping on thoracic computed tomography scans using deep neural networks
Accurate identification of emphysema subtypes and severity is crucial for effective management of COPD and the study of disease heterogeneity. Manual analysis of emphysema subtypes and severity is laborious and subjective. To address this challenge, we present a deep learning-based approach for automating the Fleischner Society’s visual score system for emphysema subtyping and severity analysis. We trained and evaluated our algorithm using 9650 subjects from the COPDGene study. Our algorithm achieved the predictive accuracy at 52%, outperforming a previously published method’s accuracy of 45%. In addition, the agreement between the predicted scores of our method and the visual scores was good, where the previous method obtained only moderate agreement. Our approach employs a regression training strategy to generate categorical labels while simultaneously producing high-resolution localized activation maps for visualizing the network predictions. By leveraging these dense activation maps, our method possesses the capability to compute the percentage of emphysema involvement per lung in addition to categorical severity scores. Furthermore, the proposed method extends its predictive capabilities beyond centrilobular emphysema to include paraseptal emphysema subtypes.</p
The Mass-Concentration Relation and the Stellar-to-Halo Mass Ratio in the CFHT Stripe 82 Survey
We present a new measurement of the mass-concentration relation and the
stellar-to-halo mass ratio over the halo mass range to
. To achieve this, we use weak lensing measurements
from the CFHT Stripe 82 Survey (CS82), combined with the central galaxies from
the redMaPPer cluster catalogue and the LOWZ/CMASS galaxy sample of the Sloan
Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey Tenth Data
Release. The stacked lensing signals around these samples are modelled as a sum
of contributions from the central galaxy, its dark matter halo, and the
neighboring halos, as well as a term for possible centering errors. We measure
the mass-concentration relation: with
for and for . These amplitudes and slopes are completely
consistent with predictions from recent simulations. We also measure the
stellar-to-halo mass ratio for our samples, and find results consistent with
previous measurements from lensing and other techniques.Comment: 10 pages, 3 figures, 3 table
Chartis Measurement of Collateral Ventilation:Conscious Sedation versus General Anesthesia
BACKGROUND: Absence of interlobar collateral ventilation using the Chartis measurement is the key predictor for successful endobronchial valve treatment in severe emphysema. Chartis was originally validated in spontaneous breathing patients under conscious sedation (CS); however, this can be challenging due to cough, mucus secretion, mucosal swelling, and bronchoconstriction. Performing Chartis under general anesthesia (GA) avoids these problems and may result in an easier procedure with a higher success rate. However, using Chartis under GA with positive pressure ventilation has not been validated. OBJECTIVES: In this study we investigated the impact of anesthesia technique, CS versus GA, on the feasibility and outcomes of Chartis measurement. METHODS: We retrospectively analyzed all Chartis measurements performed at our hospital from October 2010 until December 2017. RESULTS: We analyzed 250 emphysema patients (median forced expiratory volume in 1 s 26%, range 12-52% predicted). In 121 patients (48%) the measurement was performed using CS, in 124 (50%) using GA, and in 5 (2%) both anesthesia techniques were used. In total, 746 Chartis readings were analyzed (432 CS, 277 GA, and 37 combination). Testing under CS took significantly longer than GA (median 19 min [range 5-65] vs. 11 min [3-35], p < 0.001) and required more measurements (3 [1-13] vs. 2 [1-6], p < 0.001). There was no significant difference in target lobe volume reduction after treatment (-1,123 mL [-3,604 to 332] in CS vs. -1,251 mL [-3,333 to -1] in GA, p = 0.35). CONCLUSIONS: In conclusion, Chartis measurement under CS took significantly longer and required more measurements than under GA, without a difference in treatment outcome. We recommend a prospective trial comparing both techniques within the same patients to validate this approach
Cosmological constraints from weak lensing peak statistics with Canada-France-Hawaii Telescope Stripe 82 Survey
We derived constraints on cosmological parameters using weak lensing peak statistics measured on the ∼ 130 deg2 of the Canada-France-Hawaii Telescope Stripe 82 Survey. This analysis demonstrates the feasibility of using peak statistics in cosmological studies. For our measurements, we considered peaks with signal-to-noise ratio in the range of ν = [3, 6]. For a flat Λ cold dark matter model with only (Ωm, σ8) as free parameters, we constrained the parameters of the following relation Σ8 = σ8(Ωm/0.27)α to be Σ8 = 0.82 ± 0.03 and α = 0.43 ± 0.02. The α value found is considerably smaller than the one measured in two-point and three-point cosmic shear correlation analyses, showing a significant complement of peak statistics to standard weak lensing cosmological studies. The derived constraints on (Ωm, σ8) are fully consistent with the ones from either WMAP9 or Planck. From the weak lensing peak abundances alone, we obtained marginalized mean values of and σ8 = 0.81 ± 0.26. Finally, we also explored the potential of using weak lensing peak statistics to constrain the mass-concentration relation of dark matter haloes simultaneously with cosmological parameter
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