145 research outputs found
Unsupervised Echocardiography Registration through Patch-based MLPs and Transformers
Image registration is an essential but challenging task in medical image
computing, especially for echocardiography, where the anatomical structures are
relatively noisy compared to other imaging modalities. Traditional
(non-learning) registration approaches rely on the iterative optimization of a
similarity metric which is usually costly in time complexity. In recent years,
convolutional neural network (CNN) based image registration methods have shown
good effectiveness. In the meantime, recent studies show that the
attention-based model (e.g., Transformer) can bring superior performance in
pattern recognition tasks. In contrast, whether the superior performance of the
Transformer comes from the long-winded architecture or is attributed to the use
of patches for dividing the inputs is unclear yet. This work introduces three
patch-based frameworks for image registration using MLPs and transformers. We
provide experiments on 2D-echocardiography registration to answer the former
question partially and provide a benchmark solution. Our results on a large
public 2D echocardiography dataset show that the patch-based MLP/Transformer
model can be effectively used for unsupervised echocardiography registration.
They demonstrate comparable and even better registration performance than a
popular CNN registration model. In particular, patch-based models better
preserve volume changes in terms of Jacobian determinants, thus generating
robust registration fields with less unrealistic deformation. Our results
demonstrate that patch-based learning methods, whether with attention or not,
can perform high-performance unsupervised registration tasks with adequate time
and space complexity. Our codes are available
https://gitlab.inria.fr/epione/mlp\_transformer\_registratio
EVIL: Evidential Inference Learning for Trustworthy Semi-supervised Medical Image Segmentation
Recently, uncertainty-aware methods have attracted increasing attention in
semi-supervised medical image segmentation. However, current methods usually
suffer from the drawback that it is difficult to balance the computational
cost, estimation accuracy, and theoretical support in a unified framework. To
alleviate this problem, we introduce the Dempster-Shafer Theory of Evidence
(DST) into semi-supervised medical image segmentation, dubbed Evidential
Inference Learning (EVIL). EVIL provides a theoretically guaranteed solution to
infer accurate uncertainty quantification in a single forward pass. Trustworthy
pseudo labels on unlabeled data are generated after uncertainty estimation. The
recently proposed consistency regularization-based training paradigm is adopted
in our framework, which enforces the consistency on the perturbed predictions
to enhance the generalization with few labeled data. Experimental results show
that EVIL achieves competitive performance in comparison with several
state-of-the-art methods on the public dataset
Intracellular Accumulation of Linezolid and Florfenicol in OptrA-Producing Enterococcus faecalis and Staphylococcus aureus
The optrA gene, which confers transferable resistance to oxazolidinones and phenicols, is defined as an ATP-binding cassette (ABC) transporter but lacks transmembrane domains. The resistance mechanism of optrA and whether it involves antibiotic efflux or ribosomal protection remain unclear. In this study, we determined the MIC values of all bacterial strains by broth microdilution, and used ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry to quantitatively determine the intracellular concentrations of linezolid and florfenicol in Enterococcus faecalis and Staphylococcus aureus. Linezolid and florfenicol both accumulated in susceptible strains and optrA-carrying strains of E. faecalis and S. aureus. No significant differences were observed in the patterns of drug accumulation among E. faecalis JH2-2, E. faecalis JH2-2/pAM401, and E. faecalis JH2-2/pAM401+optrA, but also among S. aureus RN4220, S. aureus RN4220/pAM401, and S. aureus RN4220/pAM401+optrA. ANOVA scores also suggested similar accumulation conditions of the two target compounds in susceptible strains and optrA-carrying strains. Based on our findings, the mechanism of optrA-mediated resistance to oxazolidinones and phenicols obviously does not involve active efflux and the OptrA protein does not confer resistance via efflux like other ABC transporters
Two Heads are Better than One: Towards Better Adversarial Robustness by Combining Transduction and Rejection
Both transduction and rejection have emerged as important techniques for
defending against adversarial perturbations. A recent work by Tram\`er showed
that, in the rejection-only case (no transduction), a strong rejection-solution
can be turned into a strong (but computationally inefficient) non-rejection
solution. This detector-to-classifier reduction has been mostly applied to give
evidence that certain claims of strong selective-model solutions are
susceptible, leaving the benefits of rejection unclear. On the other hand, a
recent work by Goldwasser et al. showed that rejection combined with
transduction can give provable guarantees (for certain problems) that cannot be
achieved otherwise. Nevertheless, under recent strong adversarial attacks
(GMSA, which has been shown to be much more effective than AutoAttack against
transduction), Goldwasser et al.'s work was shown to have low performance in a
practical deep-learning setting. In this paper, we take a step towards
realizing the promise of transduction+rejection in more realistic scenarios.
Theoretically, we show that a novel application of Tram\`er's
classifier-to-detector technique in the transductive setting can give
significantly improved sample-complexity for robust generalization. While our
theoretical construction is computationally inefficient, it guides us to
identify an efficient transductive algorithm to learn a selective model.
Extensive experiments using state of the art attacks (AutoAttack, GMSA) show
that our solutions provide significantly better robust accuracy
Robust Split Federated Learning for U-shaped Medical Image Networks
U-shaped networks are widely used in various medical image tasks, such as
segmentation, restoration and reconstruction, but most of them usually rely on
centralized learning and thus ignore privacy issues. To address the privacy
concerns, federated learning (FL) and split learning (SL) have attracted
increasing attention. However, it is hard for both FL and SL to balance the
local computational cost, model privacy and parallel training simultaneously.
To achieve this goal, in this paper, we propose Robust Split Federated Learning
(RoS-FL) for U-shaped medical image networks, which is a novel hybrid learning
paradigm of FL and SL. Previous works cannot preserve the data privacy,
including the input, model parameters, label and output simultaneously. To
effectively deal with all of them, we design a novel splitting method for
U-shaped medical image networks, which splits the network into three parts
hosted by different parties. Besides, the distributed learning methods usually
suffer from a drift between local and global models caused by data
heterogeneity. Based on this consideration, we propose a dynamic weight
correction strategy (\textbf{DWCS}) to stabilize the training process and avoid
model drift. Specifically, a weight correction loss is designed to quantify the
drift between the models from two adjacent communication rounds. By minimizing
this loss, a correction model is obtained. Then we treat the weighted sum of
correction model and final round models as the result. The effectiveness of the
proposed RoS-FL is supported by extensive experimental results on different
tasks. Related codes will be released at https://github.com/Zi-YuanYang/RoS-FL.Comment: 11 pages, 5 figure
Combining Context and Knowledge Representations for Chemical-Disease Relation Extraction
Automatically extracting the relationships between chemicals and diseases is
significantly important to various areas of biomedical research and health
care. Biomedical experts have built many large-scale knowledge bases (KBs) to
advance the development of biomedical research. KBs contain huge amounts of
structured information about entities and relationships, therefore plays a
pivotal role in chemical-disease relation (CDR) extraction. However, previous
researches pay less attention to the prior knowledge existing in KBs. This
paper proposes a neural network-based attention model (NAM) for CDR extraction,
which makes full use of context information in documents and prior knowledge in
KBs. For a pair of entities in a document, an attention mechanism is employed
to select important context words with respect to the relation representations
learned from KBs. Experiments on the BioCreative V CDR dataset show that
combining context and knowledge representations through the attention
mechanism, could significantly improve the CDR extraction performance while
achieve comparable results with state-of-the-art systems.Comment: Published on IEEE/ACM Transactions on Computational Biology and
Bioinformatics, 11 pages, 5 figure
Unsupervised Echocardiography Registration through Patch-based MLPs and Transformers
International audienceImage registration is an essential but challenging task in medical image computing, especially for echocardiography, where the anatomical structures are relatively noisy compared to other imaging modalities. Traditional (non-learning) registration approaches rely on the iterative optimization of a similarity metric which is usually costly in time complexity. In recent years, convolutional neural network (CNN) based image registration methods have shown good effectiveness. In the meantime, recent studies show that the attention-based model (e.g., Transformer) can bring superior performance in pattern recognition tasks. In contrast, whether the superior performance of the Transformer comes from the long-winded architecture or is attributed to the use of patches for dividing the inputs is unclear yet. This work introduces three patch-based frameworks for image registration using MLPs and transformers. We provide experiments on 2D-echocardiography registration to answer the former question partially and provide a benchmark solution. Our results on a large public 2D-echocardiography dataset show that the patch-based MLP/Transformer model can be effectively used for unsupervised echocardiography registration. They demonstrate comparable and even better registration performance than a popular CNN registration model. In particular, patch-based models better preserve volume changes in terms of Jacobian determinants, thus generating robust registration fields with less unrealistic deformation. Our results demonstrate that patch-based learning methods, whether with attention or not, can perform high-performance unsupervised registration tasks with adequate time and space complexity
Explainable Electrocardiogram Analysis with Wave Decomposition: Application to Myocardial Infarction Detection
International audienceAutomatic analysis of electrocardiograms with adequate explainability is a challenging task. Many deep learning based methods have been proposed for automatic classification of electrocardiograms. However, very few of them provide detailed explainable classification evidence. In our study, we explore explainable ECG classification through explicit decomposition of single-beat (median-beat) ECG signal. In particular, every single-beat ECG sample is decomposed into five subwaves and each subwave is parameterised by a Frequency Modulated Moebius. Those parameters have explicit meanings for ECG interpretation. In stead of solving the optimisation problem iteratively which is timeconsuming, we make use of an Cascaded CNN network to estimate the parameters for each single-beat ECG signal. Our preliminary results show that with appropriate position regularisation strategy, our neural network is able to estimate the subwave for P, Q, R, S, T events and maintain a good reconstruction accuracy (with R2 score 0.94 on test dataset of PTB-XL) in a unsupervised manner. Using the estimated parameters, we achieve very good classification and generalisation performance on myocardial infarction detection on four different datasets. The features of high importance are in accordance with clinical interpretations
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