IBEB - Artigos em Conferências
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- Detection of Microcalcifications in Digital Breast Tomosynthesis using Faster R-CNN and 3D Volume RenderingPublication . Matela, Nuno; Almeida, Pedro; Clarkson, Matthew; Mota, AnaMicrocalcification clusters (MCs) are one of the most important biomarkers for breast cancer and Digital Breast Tomosynthesis (DBT) has consolidated its role in breast cancer imaging. As there are mixed observations about MCs detection using DBT, it is important to develop tools that improve this task. Furthermore, the visualization mode of MCs is also crucial, as their diagnosis is associated with their 3D morphology. In this work, DBT data from a public database were used to train a faster region-based convolutional neural network (R-CNN) to locate MCs in entire DBT. Additionally, the detected MCs were further analyzed through standard 2D visualization and 3D volume rendering (VR) specifically developed for DBT data. For MCs detection, the sensitivity of our Faster R-CNN was 60% with 4 false positives. These preliminary results are very promising and can be further improved. On the other hand, the 3D VR visualization provided important information, with higher quality and discernment of the detected MCs. The developed pipeline may help radiologists since (1) it indicates specific breast regions with possible lesions that deserve additional attention and (2) as the rendering of the MCs is similar to a segmentation, a detailed complementary analysis of their 3D morphology is possible.
- Optics and Lasers @ IBEBPublication . João M. P. Coelho, Tânia Ferreira-Gonçalves; Mariana Neves Amaral, Hugo A. Ferreira; Maria Manuela Gaspar, Catarina Pinto ReisIBEB (Instituto de Biofísica e Engenharia Biomédica) is a research institute from Faculdade de Ciências da Universidade de Lisboa, that interfaces engineering with medicine and biophysics. Founded in 1992, it started researching into optics and lasers in 2009. Since then, two main areas emerged: the development of photothermal therapy for cancer, and the evaluation of the effects of laser dazzle. Regarding the first area, an irradiation procedure was tested considering a dedicated optical zoom system [1], besides using common direct irradiation. Currently, techniques capable of adapting to tumours’ contours are being developed. Also, a proof of concept on feedback wavefront shaping was achieved by applying adequate algorithms for concentrating light inside the tissues. Implemented in transmission, it allowed to increase the beam’s concentration inside a turbid media by 50% [2]. Experimental procedures were also implemented to support the development of metallic nanoparticles (NPs) capable of mediating the conversion of the energy from photons into heat. So far, the gold NPs showed to have a photothermal conversion efficiency up to 60% [3]. In addition, photoactivation of gold NPs has been tested on different types of superficial and localized cancers [4,5]. When using in vitro models, a reduction of more than 70% in cell viability was observed [3,5]. Regarding the 2nd main area, IBEB has participated in several study groups from NATO STO to evaluate the effects of laser dazzle. Within this topic, simulators have been developed [6] and the performance of subjects being dazzled whilst performing tasks requiring concentration, has been assessed using electroencephalography signals [7].
- Normative modelling detects abnormal functional connectivity in schizophreniaPublication . Saraiva, Duarte; Ferreira, HugoMachine learning (ML) applications on the diagnosis of neuropsychiatric disorders (NPD) have not reached clinical practice yet, as the continuous spectrum of NPD demands more complex, non-binary classification approaches. Herein, a ML-based normative model was created from healthy subjects, which “fails” when tested on schizophrenia patients. In particular, abnormal functional connectivity patterns were found in such patients, in agreement to what has been described in the literature. Moreover, a clustering method and analysis at the individual level indicate that subgroups may exist within the schizophrenia spectrum, suggesting that a personalized and precision-based diagnosis is within reach for such NPD.
- How the Number and Distance of Electrodes Change the Induced Electric Field in the Cortex during Multichannel tDCSPublication . Videira, Andreia S.; Canadas, Diogo; De O. Pires, Leonor; Andrade, Alexandre; Ferreira, Hugo A.; Miranda, Pedro C.; Fernandes, Sofia R.Multichannel transcranial direct current stimulation (tDCS) is a promising approach to target neuromodulation of neural networks by making use of variable number of electrodes and distances to facilitate/inhibit specific connectivity patterns. Optimization of the electric field (EF) spatial distribution through computational models can provide a more accurate definition of the stimulation settings that are more effective. In this study, we investigate the effect of increasing the number of cathodes around a central anode placed over the target. We demonstrate that anode-cathode distance has the largest influence in the EF and using more than 3 cathodes did not result in considerable changes in the EF magnitude and direction. This could be relevant for simultaneous tDCS-electroencephalography (EEG) applications, by saving electrode positions for EEG acquisition. Clinical Relevance- This study demonstrates that distance between electrodes is more relevant than electrode number in determining the electric field distribution, and that a highly-focused stimulation can be equally effective with fewer electrodes.
- Detection of Microcalcifications in Digital Breast Tomosynthesis using Faster R-CNN and 3D Volume RenderingPublication . Mota, Ana M.; Clarkson, Matthew J.; Almeida, Pedro; Matela, NunoMicrocalcification clusters (MCs) are one of the most important biomarkers for breast cancer and Digital Breast Tomosynthesis (DBT) has consolidated its role in breast cancer imaging. As there are mixed observations about MCs detection using DBT, it is important to develop tools that improve this task. Furthermore, the visualization mode of MCs is also crucial, as their diagnosis is associated with their 3D morphology. In this work, DBT data from a public database were used to train a faster region-based convolutional neural network (R-CNN) to locate MCs in entire DBT. Additionally, the detected MCs were further analyzed through standard 2D visualization and 3D volume rendering (VR) specifically developed for DBT data. For MCs detection, the sensitivity of our Faster R-CNN was 60% with 4 false positives. These preliminary results are very promising and can be further improved. On the other hand, the 3D VR visualization provided important information, with higher quality and discernme nt of the detected MCs. The developed pipeline may help radiologists since (1) it indicates specific breast regions with possible lesions that deserve additional attention and (2) as the rendering of the MCs is similar to a segmentation, a detailed complementary analysis of their 3D morphology is possible.
- Initial Study of Detection and Repeatability of Microwave Imaging with Monopole AntennasPublication . Correia, Inês; Godinho, Daniela M.We are building a new Microwave Imaging (MWI) prototype to image both the breast and the axillary region, to be used as a potential complementary method for breast cancer diagnosis. In this work, we evaluated our antennas performance with simplified breast phantoms, while testing the effect of plastic in phantoms on imaging results and the repeatability of our system. Results suggest plastic has no significant effect on imaging performance. We also observed operator's interference may hinder repeatability of the system.
- Study of Best Antenna Configuration for Axillary Microwave Imaging PrototypePublication . Godinho, Daniela M.; Conceição, Raquel C.Imaging the axillary region for detection of axillary lymph nodes metastasised by breast cancer is currently under development using microwave signals. A limited angular view justifies the study of the best antenna configuration for this application. In this paper, we perform a preliminary study to find the best antenna configurations for axillary microwave imaging. The results show the quality of target detection is affected by the choice of antenna configurations, and also that it depends on the position of the target. One of the potential candidates for antenna configuration shows promising results.
- Repository of materials mimicking dielectric properties of biological tissuesPublication . M. Godinho, Daniela; Bonello, Julian; Farrugia, Lourdes; Porter, Emily; C. Conceição, RaquelAnatomical phantoms with Tissue Mimicking Materials (TMMs) representing the properties of biological tissues, such as dielectric properties, are essential for validation of electromagnetic (EM) medical devices. In this paper, we present an open-access repository of TMMs that aims to collect and summarise ingredients and recipes of TMMs used for these applications. This repository allows to avoid duplicated efforts while creating TMMs and to accelerate the development of EM medical devices.
- Impact of Antenna Configuration and Artefact Removal Algorithms for Axillary Microwave ImagingPublication . M. Godinho, Daniela; L. Cidadão, Pedro; C. Conceição, RaquelMicrowave Imaging (MWI) has been studied to aid breast cancer staging through the detection of Axillary Lymph Nodes (ALNs) metastasised by breast cancer. The anatomy of the axillary region imposes a limited angular view on MWI prototypes which may hinder artefact removal performance and, consequently, a correct detection of ALNs. In this initial study, we compare different antenna configurations for axillary MWI, while evaluating the performance of different artefact removal algorithms. The imaging results highlight the importance of choosing an optimal combination of antenna configuration and artefact removal algorithm for accurate target detection.
- Best Practices for Accurate Results Using Numerical Solvers for Microwave Body ScreeningPublication . Martins, Raquel A.; Godinho, Daniela M.; Felício, João M.; Savazzi, Matteo; Costa, Jorge R.; Conceição, Raquel C.; Fernandes, Carlos A.In this paper, we indicate best practices that should be observed when using numerical solvers for microwave body sensing. We show the impact of not minding these aspects in the case of microwave breast scanning, using the Computer Simulation Technology software tool. To this end we simulate a homogeneous breast with a 5-mm radius spherical tumor placed inside. The breast is illuminated by a broadband antenna that operates in the 2-6 GHz band. The scattering parameters are then processed to reconstruct the reflectivity map of the breast. The results highlight that the conclusions drawn from simulations may be misleading or meaningless when the solver type or positioning of model elements (body and antennas) are not carefully applied. This is particularly critical when considering more complex scenarios, such as inhomogeneous or multilayer body models.
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