11 results on '"Joao Rebelo"'
Search Results
2. Growing Teratoma Syndrome: A Rare Outcome
- Author
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Francisco Moreira, António J. Madureira, Joao Rebelo, Ana Sofia Preto, and Margarida Morgado
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endocrine system ,Pathology ,medicine.medical_specialty ,endocrine system diseases ,Growing teratoma syndrome ,Mixed Germ Cell Tumor ,business.industry ,030232 urology & nephrology ,Case Report ,General Medicine ,urologic and male genital diseases ,medicine.disease ,Diseases of the genitourinary system. Urology ,female genital diseases and pregnancy complications ,03 medical and health sciences ,0302 clinical medicine ,Text mining ,030220 oncology & carcinogenesis ,medicine ,RC870-923 ,Ovarian cancer ,business - Abstract
Growing teratoma syndrome is a rare condition described in both testicular and ovarian cancer. We present a case of a 26-year-old male with known mixed germ cell tumor which exhibited new and progressive secondary lesions during imaging surveillance, later to be histologically characterized as teratomas.
- Published
- 2021
3. Automatic Lung Nodule Detection Combined With Gaze Information Improves Radiologists’ Screening Performance
- Author
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João Pedrosa, Carlos A. Ferreira, Joao Rebelo, Antonio José Ledo Alves da Cunha, Teresa Araújo, Filipe Alves, Margarida Morgado, Aurélio Campilho, Guilherme Aresta, Isabel Ramos, and Eduardo Negrão
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Lung Neoplasms ,Computer science ,Fixation, Ocular ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Deep Learning ,0302 clinical medicine ,Text mining ,Health Information Management ,Radiologists ,medicine ,Humans ,Sensitivity (control systems) ,Electrical and Electronic Engineering ,Eye-Tracking Technology ,Lung cancer ,business.industry ,Pattern recognition ,medicine.disease ,Gaze ,Computer Science Applications ,Informatics ,Fixation (visual) ,Task analysis ,Radiographic Image Interpretation, Computer-Assisted ,Eye tracking ,Artificial intelligence ,Tomography, X-Ray Computed ,business ,030217 neurology & neurosurgery ,Biotechnology - Abstract
Early diagnosis of lung cancer via computed tomography can significantly reduce the morbidity and mortality rates associated with the pathology. However, searching lung nodules is a high complexity task, which affects the success of screening programs. Whilst computer-aided detection systems can be used as second observers, they may bias radiologists and introduce significant time overheads. With this in mind, this study assesses the potential of using gaze information for integrating automatic detection systems in the clinical practice. For that purpose, 4 radiologists were asked to annotate 20 scans from a public dataset while being monitored by an eye tracker device, and an automatic lung nodule detection system was developed. Our results show that radiologists follow a similar search routine and tend to have lower fixation periods in regions where finding errors occur. The overall detection sensitivity of the specialists was $\mathbf {0.67\pm 0.07}$ , whereas the system achieved 0.69. Combining the annotations of one radiologist with the automatic system significantly improves the detection performance to similar levels of two annotators. Filtering automatic detection candidates only for low fixation regions still significantly improves the detection sensitivity without increasing the number of false-positives.
- Published
- 2020
4. Classification of Lung Nodules in CT Volumes Using the Lung-RADS™ Guidelines with Uncertainty Parameterization
- Author
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Carlos Abreu Ferreira, Joao Rebelo, Antonio José Ledo Alves da Cunha, Eduardo Negrão, Isabel Ramos, Guilherme Aresta, Aurélio Campilho, and João Pedrosa
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business.industry ,Computer science ,Deep learning ,Nodule (medicine) ,Sample (statistics) ,02 engineering and technology ,Function (mathematics) ,medicine.disease ,Malignancy ,computer.software_genre ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Region of interest ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,020201 artificial intelligence & image processing ,Artificial intelligence ,Data mining ,medicine.symptom ,Lung cancer ,business ,computer - Abstract
Currently, lung cancer is the most lethal in the world. In order to make screening and follow-up a little more systematic, guidelines have been proposed. Therefore, this study aimed to create a diagnostic support approach by providing a patient label based on the LUNG-RADS™ guidelines. The only input required by the system is the nodule centroid to take the region of interest for the input of the classification system. With this in mind, two deep learning networks were evaluated: a Wide Residual Network and a DenseNet. Taking into account the annotation uncertainty we proposed to use sample weights that are introduced in the loss function, allowing nodules with a high agreement in the annotation process to take a greater impact on the training error than its counterpart. The best result was achieved with the Wide Residual Network with sample weights achieving a nodule-wise LUNG-RADS™ labelling accuracy of $0.735\pm 0.003$ .
- Published
- 2020
5. Ultrasound elastography: compression elastography and shear-wave elastography in the assessment of tendon injury
- Author
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Rui Prado-Costa, Ana Sofia Preto, João Monteiro-Barroso, and Joao Rebelo
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lcsh:Medical physics. Medical radiology. Nuclear medicine ,musculoskeletal diseases ,medicine.medical_specialty ,lcsh:R895-920 ,Context (language use) ,Review ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Sonoelastography ,0302 clinical medicine ,Ultrasound ,medicine ,Radiology, Nuclear Medicine and imaging ,Rotator cuff ,Neuroradiology ,Tendon injury ,medicine.diagnostic_test ,business.industry ,030229 sport sciences ,musculoskeletal system ,medicine.disease ,Tendon ,medicine.anatomical_structure ,Tendinopathy ,Radiology ,Quadriceps tendon ,Elastography ,business - Abstract
Ultrasound elastography (USE) is a recent technology that has experienced major developments in the past two decades. The assessment of the main mechanical properties of tissues can be made with this technology by characterisation of their response to stress. This article reviews the two major techniques used in musculoskeletal elastography, compression elastography (CE) and shear-wave elastography (SWE), and evaluates the studies published on major electronic databases that use both techniques in the context of tendon pathology. CE accounts for more studies than SWE. The mechanical properties of tendons, particularly their stiffness, may be altered in the presence of tendon injury. CE and SWE have already been used for the assessment of Achilles tendons, patellar tendon, quadriceps tendon, epicondylar tendons and rotator cuff tendons and muscles. Achilles tendinopathy is the most studied tendon injury with USE, including the postoperative period after surgical repair of Achilles rupture tendon. In relation to conventional ultrasound (US), USE potentially increases the sensitivity and diagnostic accuracy in tendinopathy, and can detect pathological changes before they are visible in conventional US imaging. Several technical limitations are recognised, and standardisation is necessary to ensure repeatability and comparability of the results when using these techniques. Still, USE is a promising technique under development and may be used not only to promote an early diagnosis, but also to identify the risk of injury and to support the evaluation of rehabilitation interventions. Key Points • USE is used for the assessment of the mechanical properties of tissues, including the tendons. • USE increases diagnostic performance when coupled to conventional US imaging modalities. • USE will be useful in early diagnosis, tracking outcomes and monitoring treatments of tendon injury. • Technical issues and lack of standardisation limits USE use in the assessment of tendon injury.
- Published
- 2018
6. LNDetector: A Flexible Gaze Characterisation Collaborative Platform for Pulmonary Nodule Screening
- Author
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Isabel Ramos, Guilherme Aresta, Joao Rebelo, Antonio José Ledo Alves da Cunha, Aurélio Campilho, Eduardo Negrão, and João Pedrosa
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Visual search ,Nodule detection ,medicine.diagnostic_test ,business.industry ,Computer science ,Computed tomography ,Machine learning ,computer.software_genre ,Gaze ,ComputingMethodologies_PATTERNRECOGNITION ,Computer-aided diagnosis ,Pulmonary nodule ,medicine ,Classification methods ,Segmentation ,Artificial intelligence ,business ,computer - Abstract
Lung cancer is the deadliest type of cancer worldwide and late detection is one of the major factors for the low survival rate of patients. Low dose computed tomography has been suggested as a potential early screening tool but manual screening is costly, time-consuming and prone to interobserver variability. This has fueled the development of automatic methods for the detection, segmentation and characterisation of pulmonary nodules but its application to the clinical routine is challenging. In this study, a platform for the development, deployment and testing of pulmonary nodule computer-aided strategies is presented: LNDetector. LNDetector integrates image exploration and nodule annotation tools as well as advanced nodule detection, segmentation and classification methods and gaze characterisation. Different processing modules can easily be implemented or replaced to test their efficiency in clinical environments and the use of gaze analysis allows for the development of collaborative strategies. The potential use of this platform is shown through a combination of visual search, gaze characterisation and automatic nodule detection tools for an efficient and collaborative computer-aided strategy for pulmonary nodule screening.
- Published
- 2019
7. Automatic Lung Reference Model
- Author
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Márcio Rodrigues, João Pedrosa, Isabel Ramos, Aurélio Campilho, André Carvalho, Patrícia Leitão, Joao Rebelo, Antonio José Ledo Alves da Cunha, Marlene Machado, Carlos A. Ferreira, and Eduardo Negrão
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Standard anatomical position ,medicine.medical_specialty ,Lung ,medicine.anatomical_structure ,medicine.diagnostic_test ,business.industry ,Medicine ,Computed tomography ,Radiology ,business ,Lung cancer ,medicine.disease ,Reference model - Abstract
The lung cancer diagnosis is based on the search of lung nodules. Besides its characterization, it is also common to register the anatomical position of these findings. Even though computed-aided diagnosis systems tend to help in these tasks, there is still lacking a complete system that can qualitatively label the nodules in lung regions. In this way, this paper proposes an automatic lung reference model to facilitate the report of nodules between computed-aided diagnosis systems and the radiologist, and among radiologists. The model was applied to 115 computed tomography scans with manually and automatically segmented lobes, and the obtained sectors’ variability was evaluated. As the sectors average variability within lobes is less or equal to 0.14, the model can be a good way to promote the report of lung nodules.
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- 2019
8. Bilateral Robot Teleoperation: A Wearable Arm Exoskeleton Featuring an Intuitive User Interface
- Author
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Andre Schiele, Thomas Sednaoui, Thomas Krueger, Joao Rebelo, and Emiel den Exter
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Engineering ,business.industry ,Wearable computer ,Robot end effector ,Computer Science Applications ,law.invention ,Exoskeleton ,Robot control ,Control and Systems Engineering ,law ,Teleoperation ,Robot ,Electrical and Electronic Engineering ,User interface ,business ,Simulation ,Haptic technology - Abstract
Teleoperation systems are used when human planning and decision-making capabilities are needed during robotic remote operations. To execute meaningful tasks remotely, the operator has to be able to simultaneously control multiple degrees of freedom (DoFs) of the slave robot and efficiently receive information from the remote site. In these cases, haptic feedback has been shown to improve the operator's task execution performance [1].
- Published
- 2014
9. Haptics-2 — A system for bilateral control experiments from space to ground via geosynchronous satellites
- Author
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Manuel Aiple, F. van der Hulst, E. den Exter, Thomas Kruger, E. Mattheson, Andre Schiele, Stefan Kimmer, Joao Rebelo, A. Hernandez, and Jan Smisek
- Subjects
0209 industrial biotechnology ,Telerobotics ,Handshake ,InformationSystems_INFORMATIONINTERFACESANDPRESENTATION(e.g.,HCI) ,Computer science ,Geosynchronous orbit ,02 engineering and technology ,GeneralLiterature_MISCELLANEOUS ,020901 industrial engineering & automation ,Teleoperation ,International Space Station ,Satellite ,Simulation ,Haptic technology - Abstract
On June 5th at 21:10 CEST, the European Space Agency's Telerobotics and Haptics Laboratory conducted the first in history haptic handshake between space and Earth. This demonstration was part of the Haptics-2 experiment, which makes use of two haptic joysticks; one located in space on-board the International Space Station (ISS), and the other one on ground at ESA's laboratory in the Netherlands. Both systems can be connected through the TDRSS geosynchronous satellites via a real-time data link with sufficient performance to perform haptic teleoperation tests. This paper describes the mechatronic design of the haptic devices, the software and the system implementation required for the Haptics-2 experiment. It reports results of a real-time high-frequency characterization of the satellite data-link indicating a round-trip time delay of approximately 850 milliseconds and presents mechatronic performance data of the haptic joysticks. Moreover, the paper presents experimental results from the first haptic handshake conducted between space and ground with astronauts on-board the ISS.
- Published
- 2016
10. Performance analysis of time-delay bilateral teleoperation using impedance-controlled slaves
- Author
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Joao Rebelo and Andre Schiele
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Engineering ,business.industry ,Stiffness ,Proportional control ,Transparency (human–computer interaction) ,Operator (computer programming) ,Control theory ,Teleoperation ,medicine ,Robot ,medicine.symptom ,business ,Electrical impedance ,Simulation - Abstract
Recently developed impedance-controlled robots are better suited than conventional industrial robots for executing human-like contact tasks. However, performance of a system when using such device as a slave in time-delay bilateral teleoperation is still unknown. It is the goal of this paper to analyse the performance of a 4-channel time-delay bilateral teleoperation system with an impedance-type master device commanding an impedance-controlled slave. Using the newly introduced reflected damping in free-air criterion, it is shown that the damping felt by the human operator interacting with the system while the slave is in free-air is dependent on the local controller parameters and increases linearly with the time-delay with a factor dependent on the master and slave proportional controller gains. The transparency analysis of the system shows that, independently of the time-delay or controller parameters, a stiffness equal to that of the environment is transmitted to the operator. The experimental validation, using a 1-dof master-slave teleoperation system, shows that the proposed criterion can approximate the identified damping with an accuracy of 5% for time-delay values up to 30 ms. It is also highlighted by the experimental results that, in the transition between free-air and rigid contact, the impedance rendered to the operator is lower than that of the actual environment.
- Published
- 2015
11. Time domain passivity controller for 4-channel time-delay bilateral teleoperation
- Author
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Andre Schiele and Joao Rebelo
- Subjects
Engineering ,business.industry ,Passivity ,Control engineering ,Transparency (human–computer interaction) ,Equipment Design ,Robotics ,Models, Theoretical ,Computer Science Applications ,Time ,Human-Computer Interaction ,User-Computer Interface ,Control theory ,Touch ,Teleoperation ,Humans ,Computer Simulation ,Voltage source ,Representation (mathematics) ,business ,Algorithms ,Communication channel ,Haptic technology - Abstract
This paper presents an extension of the time-domain passivity control approach to a four-channel bilateral controller under the effects of time delays. Time-domain passivity control has been used successfully to stabilize teleoperation systems with position-force and position-position controllers; however, the performance with such control architectures is sub-optimal both with and without time delays. This work extends the network representation of the time-domain passivity controller to the four-channel architecture, which provides perfect transparency to the user without time delay. The proposed architecture is based on modelling the controllers as dependent voltage sources and using only series passivity controllers. The obtained results are shown on a one degree-of-freedom setup and illustrate the stabilization behaviour of the proposed controller when time delay is present in the communication channel.
- Published
- 2014
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