15 research outputs found
Improving Automated Hemorrhage Detection in Sparse-view Computed Tomography via Deep Convolutional Neural Network based Artifact Reduction
Purpose: Sparse-view computed tomography (CT) is an effective way to reduce
dose by lowering the total number of views acquired, albeit at the expense of
image quality, which, in turn, can impact the ability to detect diseases. We
explore deep learning-based artifact reduction in sparse-view cranial CT scans
and its impact on automated hemorrhage detection. Methods: We trained a U-Net
for artefact reduction on simulated sparse-view cranial CT scans from 3000
patients obtained from a public dataset and reconstructed with varying levels
of sub-sampling. Additionally, we trained a convolutional neural network on
fully sampled CT data from 17,545 patients for automated hemorrhage detection.
We evaluated the classification performance using the area under the receiver
operator characteristic curves (AUC-ROCs) with corresponding 95% confidence
intervals (CIs) and the DeLong test, along with confusion matrices. The
performance of the U-Net was compared to an analytical approach based on total
variation (TV). Results: The U-Net performed superior compared to unprocessed
and TV-processed images with respect to image quality and automated hemorrhage
diagnosis. With U-Net post-processing, the number of views can be reduced from
4096 (AUC-ROC: 0.974; 95% CI: 0.972-0.976) views to 512 views (0.973;
0.971-0.975) with minimal decrease in hemorrhage detection (P<.001) and to 256
views (0.967; 0.964-0.969) with a slight performance decrease (P<.001).
Conclusion: The results suggest that U-Net based artifact reduction
substantially enhances automated hemorrhage detection in sparse-view cranial
CTs. Our findings highlight that appropriate post-processing is crucial for
optimal image quality and diagnostic accuracy while minimizing radiation dose.Comment: 11 pages, 6 figures, 1 tabl
Optimizing Convolutional Neural Networks for Chronic Obstructive Pulmonary Disease Detection in Clinical Computed Tomography Imaging
Purpose: To optimize the binary detection of Chronic Obstructive Pulmonary
Disease (COPD) based on emphysema presence in the lung with convolutional
neural networks (CNN) by exploring manually adjusted versus automated
window-setting optimization (WSO) on computed tomography (CT) images.
Methods: 7,194 CT images (3,597 with COPD; 3,597 healthy controls) from 78
subjects (43 with COPD; 35 healthy controls) were selected retrospectively
(10.2018-12.2019) and preprocessed. For each image, intensity values were
manually clipped to the emphysema window setting and a baseline 'full-range'
window setting. Class-balanced train, validation, and test sets contained
3,392, 1,114, and 2,688 images. The network backbone was optimized by comparing
various CNN architectures. Furthermore, automated WSO was implemented by adding
a customized layer to the model. The image-level area under the Receiver
Operating Characteristics curve (AUC) [lower, upper limit 95% confidence] and
P-values calculated from one-sided Mann-Whitney U-test were utilized to compare
model variations.
Results: Repeated inference (n=7) on the test set showed that the DenseNet
was the most efficient backbone and achieved a mean AUC of 0.80 [0.76, 0.85]
without WSO. Comparably, with input images manually adjusted to the emphysema
window, the DenseNet model predicted COPD with a mean AUC of 0.86 [0.82, 0.89]
(P=0.03). By adding a customized WSO layer to the DenseNet, an optimal window
in the proximity of the emphysema window setting was learned automatically, and
a mean AUC of 0.82 [0.78, 0.86] was achieved.
Conclusion: Detection of COPD with DenseNet models was improved by WSO of CT
data to the emphysema window setting range
Natural Glycoforms of Human Interleukin 6 show atypical plasma clearance
A library of glycoforms of human interleukin 6 (ILâ6) comprising complex and mannosidic Nâglycans was generated by semisynthesis. The three segments were connected by sequential native chemical ligation followed by twoâstep refolding. The central glycopeptide segments were assembled by pseudoprolineâassisted Lansbury aspartylation and subsequent enzymatic elongation of complex Nâglycans. Nine ILâ6 glycoforms were synthesized, seven of which were evaluated for in vivo plasma clearance in rats and compared to nonâglycosylated recombinant ILâ6 from E. coli. Each ILâ6 glycoform was tested in three animals and reproducibly showed individual serum clearances depending on the structure of the Nâglycan. The clearance rates were atypical, since the 2,6âsialylated glycoforms of ILâ6 cleared faster than the corresponding asialo ILâ6 with terminal galactoses. Compared to nonâglycosylated ILâ6 the plasma clearance of ILâ6 glycoforms was delayed in the presence of larger and multibranched Nâglycans in most case
Synergistic effect of cisplatin and synchrotron irradiation on F98 gliomas growing in nude mice
New Electrostatic Phase Plate for Phase-Contrast Transmission Electron Microscopy and Its Application for Wave-Function Reconstruction
Towards subject-level cerebral infarction classification of CT scans using convolutional networks.
Automatic evaluation of 3D volumes is a topic of importance in order to speed up clinical decision making. We describe a method to classify computed tomography scans on volume level for the presence of non-acute cerebral infarction. This is not a trivial task, as the lesions are often similar to other areas in the brain regarding shape and intensity. A three stage architecture is used for classification: 1) A cranial cavity segmentation network is developed, trained and applied. 2) Region proposals are generated 3) Connected regions are classified using a multi-resolution, densely connected 3D convolutional network. Mean area under curve values for subject level classification are 0.95 for the unstratified test set, 0.88 for stratification by patient age and 0.93 for stratification by CT scanner model. We use a partly segmented dataset of 555 scans of which 186 scans are used in the unstratified test set. Furthermore we examine possible dataset bias for scanner model and patient age parameters. We show a successful application of the proposed three-stage model for full volume classification. In contrast to black-box approaches, the convolutional network's decision can be further assessed by examination of intermediate segmentation results
Pressure Control of Nonferroelastic Ferroelectric Domains in ErMnOâ
Mechanical pressure controls the structural, electric, and magnetic order in solid-state systems, allowing tailoring of their physical properties. A well-established example is ferroelastic ferroelectrics, where the coupling between pressure and the primary symmetry-breaking order parameter enables hysteretic switching of the strain state and ferroelectric domain engineering. Here, we study the pressure-driven response in a nonferroelastic ferroelectric, ErMnOâ, where the classical stressâstrain coupling is absent and the domain formation is governed by creationâannihilation processes of topological defects. By annealing ErMnOâ polycrystals under variable pressures in the MPa regime, we transform nonferroelastic vortex-like domains into stripe-like domains. The width of the stripe-like domains is determined by the applied pressure as we confirm by three-dimensional phase field simulations, showing that pressure leads to oriented layer-like periodic domains. Our work demonstrates the possibility to utilize mechanical pressure for domain engineering in nonferroelastic ferroelectrics, providing a lever to control their dielectric and piezoelectric responses.ISSN:1530-6984ISSN:1530-699
Liver lesion localisation and classification with convolutional neural networks: a comparison between conventional and spectral computed tomography
Purpose: To evaluate the benefit of the additional available information present in spectral CT datasets, as compared to conventional CT datasets, when utilizing convolutional neural networks for fully automatic localisation and classification of liver lesions in CT images. Materials and Methods: Conventional and spectral CT images (iodine maps, virtual monochromatic images (VMI)) were obtained from a spectral dual-layer CT system. Patient diagnosis were known from the clinical reports and classified into healthy, cyst and hypodense metastasis. In order to compare the value of spectral versus conventional datasets when being passed as input to machine learning algorithms, we implemented a weakly-supervised convolutional neural network (CNN) that learns liver lesion localisation without pixel-level ground truth annotations. Regions-of-interest are selected automatically based on the localisation results and are used to train a second CNN for liver lesion classification (healthy, cyst, hypodense metastasis). The accuracy of lesion localisation was evaluated using the Euclidian distances between the ground truth centres of mass and the predicted centres of mass. Lesion classification was evaluated by precision, recall, accuracy and F1-Score. Results: Lesion localisation showed the best results for spectral information with distances of 8.22 10.72 mm, 8.78 15.21 mm and 8.29 12.97 mm for iodine maps, 40 keV and 70 keV VMIs, respectively. With conventional data distances of 10.58 17.65 mm were measured. For lesion classification, the 40 keV VMIs achieved the highest overall accuracy of 0.899 compared to 0.854 for conventional data. Conclusion: An enhanced localisation and classification is reported for spectral CT data, which demonstrates that combining machine-learning technology with spectral CT information may in the future improve the clinical workflow as well as the diagnostic accuracy
Natural Glycoforms of Human Interleukin 6 Show Atypical Plasma Clearance
A library of glycoforms of human interleukin 6 (ILâ6) comprising complex and mannosidic Nâglycans was generated by semisynthesis. The three segments were connected by sequential native chemical ligation followed by twoâstep refolding. The central glycopeptide segments were assembled by pseudoprolineâassisted Lansbury aspartylation and subsequent enzymatic elongation of complex Nâglycans. Nine ILâ6 glycoforms were synthesized, seven of which were evaluated for in vivo plasma clearance in rats and compared to nonâglycosylated recombinant ILâ6 from E. coli. Each ILâ6 glycoform was tested in three animals and reproducibly showed individual serum clearances depending on the structure of the Nâglycan. The clearance rates were atypical, since the 2,6âsialylated glycoforms of ILâ6 cleared faster than the corresponding asialo ILâ6 with terminal galactoses. Compared to nonâglycosylated ILâ6 the plasma clearance of ILâ6 glycoforms was delayed in the presence of larger and multibranched Nâglycans in most case