2018
Authors
Wanderley, DS; Carvalho, CB; Domingues, A; Peixoto, C; Pignatelli, D; Beires, J; Silva, J; Campilho, A;
Publication
Progress in Pattern Recognition, Image Analysis, Computer Vision, and Applications - 23rd Iberoamerican Congress, CIARP 2018, Madrid, Spain, November 19-22, 2018, Proceedings
Abstract
The segmentation and characterization of the ovarian structures are important tasks in gynecological and reproductive medicine. Ultrasound imaging is typically used for the medical diagnosis within this field but the understanding of the images can be difficult due to their characteristics. Furthermore, the complexity of ultrasound data may lead to a heavy image processing, which makes the application of classical methods of computer vision difficult. This work presents the first supervised fully convolutional neural network (fCNN) for the automatic segmentation of ovarian structures in B-mode ultrasound images. Due to the small dataset available, only 57 images were used for training. In order to overcome this limitation, several regularization techniques were used and are discussed in this paper. The experiments show the ability of the fCNN to learn features to distinguish ovarian structures, achieving a Dice similarity coefficient (DSC) of 0.855 for the segmentation of the stroma and a DSC of 0.955 for the follicles. When compared with a semi-automatic commercial application for follicle segmentation, the proposed fCNN achieved an average improvement of 19%. © Springer Nature Switzerland AG 2019.
2018
Authors
Smailagic, A; Costa, P; Noh, HY; Walawalkar, D; Khandelwal, K; Galdran, A; Mirshekari, M; Fagert, J; Xu, SS; Zhang, P; Campilho, A;
Publication
2018 17TH IEEE INTERNATIONAL CONFERENCE ON MACHINE LEARNING AND APPLICATIONS (ICMLA)
Abstract
Deep learning models have been successfully used in medical image analysis problems but they require a large amount of labeled images to obtain good performance. However, such large labeled datasets are costly to acquire. Active learning techniques can be used to minimize the number of required training labels while maximizing the model's performance. In this work, we propose a novel sampling method that queries the unlabeled examples that maximize the average distance to all training set examples in a learned feature space. We then extend our sampling method to define a better initial training set, without the need for a trained model, by using Oriented FAST and Rotated BRIEF (ORB) feature descriptors. We validate MedAL on 3 medical image datasets and show that our method is robust to different dataset properties. MedAL is also efficient, achieving 80% accuracy on the task of Diabetic Retinopathy detection using only 425 labeled images, corresponding to a 32% reduction in the number of required labeled examples compared to the standard uncertainty sampling technique, and a 40% reduction compared to random sampling.
2018
Authors
Figueiredo, D; Barbosa, LS;
Publication
Molecular Logic and Computational Synthetic Biology - First International Symposium, MLCSB 2018, Santiago, Chile, December 17-18, 2018, Revised Selected Papers
Abstract
A reactive model, as studied by D. Gabbay and his collaborators, can be regarded as a graph whose set of edges may be altered whenever one of them is crossed. In this paper we show how reactive models can describe biological regulatory networks and compare them to Boolean networks and piecewise-linear models, which are some of the most common kinds of models used nowadays. In particular, we show that, with respect to the identification of steady states, reactive Boolean networks lie between piecewise linear models and the usual, plain Boolean networks. We also show this ability is preserved by a suitable notion of bisimulation, and, therefore, by network minimisation. © 2019, Springer Nature Switzerland AG.
2018
Authors
Silva, MF; Virk, GS; Tokhi, MO; Malheiro, B; Ferreira, P; Guedes, P;
Publication
Human-Centric Robotics- Proceedings of the 20th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, CLAWAR 2017
Abstract
2018
Authors
Gomes, AD; Silveira, B; Dellith, J; Becker, M; Rothhard, M; Bartelt, H; Frazao, O;
Publication
IEEE PHOTONICS TECHNOLOGY LETTERS
Abstract
A sensing structure based on a cleaved silica microsphere is proposed for temperature sensing. The microsphere was cleaved using focused ion beam milling. The asymmetry in the structure introduced by the cut generates not only new cavities but also random interferometric reflections inside the microsphere. These two spectral components can be separated using low-pass and high-pass filters, respectively. The sensor response to temperature can be extracted from the cavities' component using a correlation method. The device achieved a temperature sensitivity of -10.8 +/- 0.2 pm/degrees C between 30 degrees C and 80 degrees C. The same effect is impossible to be obtained in a normal uncleaved microsphere. The random interferometric component did not provide any information on temperature using the same analysis. However, when changing the temperature, a new and completely distinct reflection spectrum with no apparent correlation with others at different temperatures was achieved.
2018
Authors
Cruz, R; Silveira, M; Cardoso, JS;
Publication
2018 International Workshop on Pattern Recognition in Neuroimaging, PRNI 2018, Singapore, Singapore, June 12-14, 2018
Abstract
The majority of computer-Aided diagnosis methods for Alzheimer's disease (AD) from brain images either address only two stages of the disease at a time (and reduce the problem to binary classification) or do not exploit the ordinal nature of the different classes. An exception is the work by Fan et al. [1], which proposed an ordinal method that obtained better performance than traditional multiclass classification. Still, special care should be taken when data is class imbalanced, i.e. when some classes are overly represented when compared to others. Building on top of [1], this work makes use of a recently published ordinal classifier, which transforms the problem into sets of pairwise ranking problems, in order to address the class imbalance in the data [2]. Several methods were experimented with, using a Support Vector Machine as the underlying estimator. The pairwise ranking approach has shown promising results, both for traditional and imbalance metrics. © 2018 IEEE.
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