76 research outputs found
Determinação da grade costal em pacientes com pectus excavatum utilizando técnicas imagiológicas sem radiação
Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Eletrónica Médica)Todas as áreas científicas que apoiam e suportam a medicina têm evoluído muito ao longo
dos anos. Uma dessas áreas é a Engenharia sendo indispensável para o eficaz e eficiente
funcionamento do que hoje conhecemos como Medicina Moderna.
A imagem médica, área muito explorada e dependente da Engenharia, tem evoluído muito e
atualmente é possível diagnosticar, tratar e melhorar procedimentos, diminuir o erro humano,
investigar com melhores práticas e até modelar próteses devido à evolução desta área. Isto tem
acontecido quer através do aperfeiçoamento dos equipamentos de aquisição de imagens
médicas, como também das técnicas de processamento de imagem usadas.
Hoje em dia, a Tomografia Computadorizada (modalidade da imagem médica) é usada como
exame de pré-diagnóstico para a correção do pectus excavatum, uma deformidade que ocorre na
parede do tórax. Contudo, a Tomografia Computadorizada não é benéfica para os pacientes
devido ao seu princípio físico de aquisição se basear em radiação, o que poderá originar a longo
prazo problemas de saúde graves. Como a correção do pectus excavatum é cada vez mais uma
cirurgia estética, onde o seu principal objetivo é evitar problemas psicológicos e de stress social
nas crianças e jovens adolescentes portadores desta deformidade, tem-se questionado a real
necessidade do uso da Tomografia Computadorizada.
Tendo em consideração a realidade descrita foi objetivo deste trabalho avaliar a possibilidade
de reconstruir um plano axial do tórax, contendo a grade costal, a partir de imagens por
ultrassons e recorrendo a técnicas de processamento imagem. O intuito desta reconstrução foi
eliminar a Tomografia Computadorizada do procedimento de modelação/dobragem automática
da prótese cirúrgica para a correção do pectus excavatum.
As técnicas e algoritmos de processamento de imagem usados e implementados, para obter
um plano axial a partir de várias imagens de ultrassons, basearam-se no realce das imagens
através de filtragem, no registo para obter as transformações entre imagens, na segmentação
das estruturas ósseas e na reconstrução do plano final a partir dos dados do registo e da
segmentação.
Os resultados preliminares obtidos, principalmente de imagens de um phantom,
demonstraram que é possível fazer reconstruções contendo informações das estruturas
presentes no plano adquirido, como também da curvatura do tórax. Imagens obtidas com o
phantom submerso em água demonstraram melhores resultados, onde as estruturas estão bem
definidas e as dimensões coincidem quando comparadas com a Tomografia Computadorizada. Dados in vivo, mostraram que é possível reconstruir planos contendo a informação anatómica,
no entanto, ainda não foi possível obter a curvatura real do tórax. Porém, o algoritmo de
segmentação das estruturas ósseas demonstrou ser capaz de realçar a superfície do osso.
Futuramente prevê-se a contínua otimização dos algoritmos, otimização dos parâmetros de
aquisição da imagem e utilização de equipamentos externos de apoio à aquisição de imagens.All the scientific areas that support medicine have evolved enormously over the years. One
such area is engineering, being indispensable for the effective and efficient functioning of what
we know today as modern medicine.
The medical imaging, a very explored and dependent area of the engineering, has greatly
progressed and nowadays it is possible to diagnose, treat, improve procedures, reduce human
error, investigate with best practices and model prosthesis due to developments in this area. This
has occurred by improving the imaging equipment as well as the medical image processing
techniques.
Nowadays, the Computed Tomography (medical image modality) is used as pre-diagnosis
examination for the correction of pectus excavatum, a deformity that occurs in the chest wall.
However, Computed Tomography is not beneficial for patients because its physical principle of
acquisition is based on radiation, which may lead to long-term serious health problems. As the
correction of pectus excavatum is more a cosmetic surgery, where its main objective is to avoid
psychological problems and social stress in children and young adolescents with this deformity, it
has been questioned the real need for the use of Computed Tomography.
Taking into account the described reality, the objective of this study was to evaluate the
possibility to reconstruct an axial plane of the chest with the rib cage using ultrasound images
and image processing techniques. The purpose of this reconstruction was to eliminate the
Computed Tomography from the procedure of automatic modeling/bending the prosthesis for
the surgical correction of pectus excavatum.
The image processing techniques and algorithms used and implemented to obtain an axial
plane, using several ultrasound images, were based in image enhancement using filtering
techniques, in registration to obtain the transformations between images, the segmentation of
bone structures and the reconstruction of the final plan from the data of registration and
segmentation.
The preliminary results, mostly from a phantom, showed that it is possible to make
reconstructions containing the information of the structures present in the scanned plan, as well
as the curvature of the chest. Acquired images with the phantom submerged in water exhibited
better results, where the structures are well defined and the dimensions match when compared
with Computed Tomography. In vivo data indicated that it is possible to reconstruct planes
containing the anatomical information, however, still cannot get the actual curvature of the chest. The segmentation algorithm of bone structures has been shown to enhance the surface of the
bone.
Hereafter, it is anticipated the continuous optimization of algorithms, the optimization of
image acquisition parameters and the use of external equipment to support the image
acquisition.Fundação para a Ciência e a Tecnologia (FCT
Assessment of shear modulus by different seismic wave-based techniques
Using combined setup of bender elements and accelerometers, tests were conducted on Coimbra sand specimens in order to measure and interpret seismic wave velocities to assess initial shear modulus. For these tests both time and frequency domain analyses were performed. Resonant column tests were also performed on the same sand to validate the results obtained with the bender elements and accelerometers setup. As is well known, in the last decades the development of new laboratory techniques to assess soil stiffness through the use of seismic wave-based techniques, has received significant attention due to its simplicity and versatility of the equipment setup. One of these techniques is the bender elements test which have been one of the most widely used, although some limitations concerning its usage. In this context, the combined use of bender elements with other seismic wave-based testing techniques, such as accelerometers or the resonant column, is quite important to compare and validate the testing techniques. Given its miniature size, the installation of accelerometers on the side of the sample is considered feasible without significant disturbance on the other measuring techniques. The resonant column is a widely used and accurate testing technique due to its reliability and repeatability. Finally, the results of this combined tests allow a critical discussion on the advantages and limitations of the use of bender elements and accelerometers, in contrast with the resonant-column for the assessment of the shear modulus in sand.This work was developed with the financial support provided by FCT (Portuguese Foundation for Science and Technology) under the research project WaveSoil - PTDC/ECM/122751/2010 from FCOMOP-01-0124-FEDER-020365 project
A new methodology for assessment of pectus excavatum correction after bar removal in Nuss procedure: preliminary study
Purpose: The objective is to present a new methodology to assess quantitatively the impact of bar removal on the anterior chest wall, among patients with pectus excavatum who have undergone the Nuss procedure, and present a preliminary study using this methodology.
Methods: We propose to acquire, for each patient, the surface of the anterior chest wall using a three-dimensional laser scanner at subsequent time points (short term: before and after surgery; long term: follow-up visit, 6 months, and 12 months after surgery). After surfaces postprocessing, the changes are assessed by overlapping and measuring the distances between surfaces.
In this preliminary study, three time points were acquired and two assessments were performed: before vs after bar removal (early) and before vs 2-8 weeks after bar removal (interim). In 21 patients, the signed distances and volumes between surfaces were computed and the data analysis was performed.
Results: This methodology revealed useful for monitoring changes in the anterior chest wall. On average, the mean, maximum, and volume variations, in the early assessment, were -0.1 +/- 0.1 cm, -0.6 +/- 0.2 cm, and 47.8 +/- 22.2 cm(3), respectively; and, in the interim assessment, were -0.5 +/- 0.2 cm, -1.3 +/- 0.4 cm, and 122.1 +/- 47.3 cm3, respectively (p < 0.05). Data analysis revealed that the time the bar was in situ was inversely and significantly correlated with postretraction and was a relevant predictor of its decrease following surgery (p < 0.05). Additionally, gender and age suggested influencing the outcome.
Conclusions: This methodology is novel, objective and safe, helping on follow-up of pectus excavatum patients. Moreover, the preliminary study suggests that the time the bar was in situ may be the main determinant of the anterior chest wall retraction following bar removal. Further studies should continue to corroborate and reinforce the preliminary findings, by increasing the sample size and performing long-term assessments.FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the projects PTDC/SAU-BEB/103368/2008 and POCI-01-0145-FEDER-007038; and by the projects NORTE-07-0124-FEDER-000017 and NORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER)info:eu-repo/semantics/publishedVersio
Measurement of shear modulus using bender elements and resonant-column
In recent times, new demands in geotechnical engineering, mainly in transportation geotechnics, require the use of advanced characterization techniques in order to accurately assess soil stiffness parameters. From this perspective, seismic wave-based techniques have received significant attention, since these allow performing the same basic measurement in the laboratory and field. With an enormous potential, bender elements are currently one of the most popular techniques used to measure reference soil properties in the very small strain range, namely the shear modulus. Bench and triaxial tests conducted on a wide range of geomaterials already demonstrated the applicability of this technique. However, the combined use of bender elements with other testing techniques, as the resonant column, is quite important in order to compare and validate some of the procedures used. In this context, bench bender elements tests were carried out on stiff sandy silt/silty sand specimens and the interpretation of seismic wave velocities was performed using time domain methods under a variety of excitations. Resonant column tests were also conducted on the same material to validate the obtained results with the bench bender elements setup. A critical discussion is made on the advantages and limitations of bender elements usage in contrast with the resonant-column for the assessment of the shear modulus, as well as some insights regarding damping. Additional tests were carried out in two distinct BE setups, one of which installed in the resonant column device, as well as ultrasonic measurements, with the purpose of validating the BE procedure and results interpretation. From this research, it was possible to compare and analyze the results obtained with the three different bender element setups and derive recommendations towards achieving reliable measurements.This work was developed with the financial support provided by FCT (Portuguese Foundation for Science and Technology) under the research project WaveSoil - PTDC/ECM/122751/2010 from FCOMOP-01-0124-FEDER-020365 project
Automatic modeling of an orthotic bracing for nonoperative correction of Pectus Carinatum
Pectus Carinatum is a deformity of the chest wall, characterized by an anterior protrusion of the sternum, often corrected surgically due to cosmetic motivation. This work presents an alternative approach to the current open surgery option, proposing a novel technique based on a personalized orthosis. Two different processes for the orthosis' personalization are presented. One based on a 3D laser scan of the patient chest, followed by the reconstruction of the thoracic wall mesh using a radial basis function, and a second one, based on a computer tomography scan followed by a neighbouring cells algorithm. The axial position where the orthosis is to be located is automatically calculated using a Ray-Triangle intersection method, whose outcome is input to a pseudo Kochenek interpolating spline method to define the orthosis curvature. Results show that no significant differences exist between the patient chest physiognomy and the curvature angle and size of the orthosis, allowing a better cosmetic outcome and less initial discomfort.The authors acknowledge to Foundation for Science
and Technology (FCT) - Portugal for the fellowships
with the references: SFRH/BD/74276/2010;
SFRH/BD/68270/2010; UMINHO/BI/95/2012; and,
SFRH/BPD/46851/2008. This work was also
supported by FCT R&D project PTDC/SAUBEB/103368/2008
Personalized dynamic phantom of the right and left ventricles based on patient-specific anatomy for echocardiography studies — Preliminary results
Dynamic phantoms of the heart are becoming a reality, with their use spread across both medical and research fields. Their purpose is to mimic the cardiac anatomy, as well as its motion. This work aims to create a dynamic, ultrasound-compatible, realistic and flexible phantom of the left and right ventricles, with application in the diagnosis, planning, treatment and training in the cardiovascular field for studies using echocardiography. Here, we focus on its design and production with polyvinyl alcohol cryogel (PVA-C), to be assembled with a pump and an electromechanical (E/M) system in a water tank. Based on a patient-specific anatomical model and produced using a 3D printing technique and molding, the PVA-C phantom mimics the ventricles' natural anatomy and material properties, while the pump and E/M systems mimic the natural movements and pressures. The PVA-C phantom was assessed by imaging and measuring it using a four-dimensional ultrasound machine. The PVA-C phantom demonstrated to be a versatile option to produce patient-specific biventricular models, preserving their shape after manufacturing and presenting good echogenic properties. Both chambers were clearly seen in the ultrasound images, together with the interventricular septum and the myocardial wall. Automated left ventricle measures revealed a decrease of its volume with regard to the designed model (98 ml to 74 ml). Overall, the preliminary results are satisfactory and encourage its use for the abovementioned purposesFEDER funds through the Competitiveness
Factors Operational Programme
(COMPETE), and by National funds through the
Foundation for Science and Technology (FCT) under the project POCI
-01-0145-FEDER-007038 and EXPL/BBB-BMD/2473/2013, and by the projects NORTE-01-0145-FEDER-000013 and NORTE-01-0145-FEDER-024300, supported by the
NORTE 2020, under the Portugal 2020 Partnership Agreement, through the
European Regional Development Fund (FEDER). J. Gomes-Fonseca, P. Morais, S.
Queirós, and F. Veloso were funded by FCT under the Ph.D. grants
PD/BDE/113597/2015, SFRH/BD/95438/2013, SFRH/BD/93443/2013, and
SFRH/BD/131545/2017info:eu-repo/semantics/publishedVersio
Assessment of 3D scanners for modeling Pectus Carinatum corrective bar
Pectus Carinatum (PC) is a chest deformity consisting on the anterior protrusion of the sternum and adjacent costal cartilages. Non-operative corrections, such as the orthotic compression brace, require previous information of the patient chest surface, to improve the overall brace fit. This paper focuses on the validation of the Kinect scanner for the modelling of an orthotic compression brace for the correction of Pectus Carinatum. To this extent, a phantom chest wall surface was acquired using two scanner systems - Kinect and Polhemus FastSCAN - and compared through CT. The results show a RMS error of 3.25mm between the CT data and the surface mesh from the Kinect sensor and 1.5mm from the FastSCAN sensor.The authors acknowledge to Foundation for
Science and Technology (FCT) - Portugal for the
fellowships with the references:
UMINHO/BI/95/2012; SFRH/BD/68270/2010;
SFRH/BD/74276/2010 and SFRH/BPD/46851/2008.
This work was also supported by FCT R&D project
PTDC/SAU-BEB/103368/2008
A dual-modal CT/US kidney phantom model for image-guided percutaneous renal access
Percutaneous renal access (PRA) is a crucial step in some minimally invasive kidney interventions. During this step, the surgeon inserts a needle through the skin until the kidney target site using fluoroscopy and ultrasound imaging. Recently, new concepts of enhanced image-guided interventions have been introduced in these interventions. However, their validation remains a challenging task. Phantom models have been presented to solve such challenge, using realistic anatomies in a controlled environment. In this work, we evaluate the accuracy of a porcine kidney phantom for validation of novel dual-modal computed tomography (CT)/ultrasound (US) image-guided strategies for PRA. A porcine kidney was combined with a tissue mimicking material (TMM) and implanted fiducial markers (FM). While the TMM mimics the surrounding tissues, the FM are used to accurately assess the registration errors between the US and CT images, providing a valid ground-truth. US and CT image acquisitions of the phantom model were performed and the FM were manually selected on both images. A rigid alignment was performed between the selected FM, presenting a root-mean-square error of 1.1 mm. Moreover, the kidney was manually segmented, presenting volumes of 203 ml and 238 ml for CT and US, respectively. The initial results are promising on achieving a realistic kidney phantom model to develop new strategies for PRA, but further work to improve the manufacturing process and to introduce motion and anatomical artifacts in the phantom is still required.This work has been funded by FEDER funds, through the Competitiveness Factors
Operational Programme (COMPETE), and by National funds, through the Foundation for Science
and Technology (FCT), under the scope of the project NORTE-01-0145-FEDER-000013, supported
by the NORTE 2020, under the Portugal 2020 Partnership Agreement, through the
European Regional Development Fund (FEDER). J. Gomes-Fonseca, A. Miranda, P. Morais, and
S. Queirós were funded by FCT under the Ph.D. grants PD/BDE/113597/2015, SFRH/BD/52059/
2012, SFRH/BD/95438/2013, and SFRH/BD/93443/2013, respectively.info:eu-repo/semantics/publishedVersio
Sublineage A1 Drives Multi-Organ Carcinogenesis
by Fundação para a Ciência e Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior (FCT/MCTES, Portugal) through national funds to iNOVA4Health (UIDB/04462/2020 and UIDP/ 04462/2020); from the GenomePT project (POCI-01-0145-FEDER-022184), supported by COMPETE 2020—Operational Programme for Competitiveness and Internationalisation (POCI), Lisboa Portugal Regional Operational Programme (Lisboa2020), Algarve Portugal Regional Operational Pro- Int. J. Mol. Sci. 2022, 23, 12371 8 of 10 gramme (CRESC Algarve2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), and by Fundação para a Ciência e a Tecnologia (FCT). This work was also supported by Fundos FEDER through the Programa Operacional Factores de Competitividade—COMPETE and by Fundos Nacionais through the Fundação para a Ciência e a Tecnologia within the scope of the project UID/BIM/00009/2019 (Centre for Toxicogenomics and Human Health-ToxOmics); and from LA/P/0045/2020 (ALiCE), UIDB/00511/2020 and UIDP/00511/2020 (LEPABE), funded by national funds through FCT/MCTES (PIDDAC); 2SMART (NORTE-01-0145- FEDER-000054), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF).The study of human papillomavirus (HPV)-induced carcinogenesis uses multiple in vivo mouse models, one of which relies on the cytokeratin 14 gene promoter to drive the expression of all HPV early oncogenes. This study aimed to determine the HPV16 variant and sublineage present in the K14HPV16 mouse model. This information can be considered of great importance to further enhance this K14HPV16 model as an essential research tool and optimize its use for basic and translational studies. Our study evaluated HPV DNA from 17 samples isolated from 4 animals, both wild-type (n = 2) and HPV16-transgenic mice (n = 2). Total DNA was extracted from tissues and the detection of HPV16 was performed using a qPCR multiplex. HPV16-positive samples were subsequently whole-genome sequenced by next-generation sequencing techniques. The phylogenetic positioning clearly shows K14HPV16 samples clustering together in the sub-lineage A1 (NC001526.4). A comparative genome analysis of K14HPV16 samples revealed three mutations to the human papillomaviruses type 16 sublineage A1 representative strain. Knowledge of the HPV 16 variant is fundamental, and these findings will allow the rational use of this animal model to explore the role of the A1 sublineage in HPV-driven cancer.publishersversionpublishe
Patient-physician discordance in assessment of adherence to inhaled controller medication: a cross-sectional analysis of two cohorts
We aimed to compare patient's and physician's ratings of inhaled medication adherence and to identify predictors of patient-physician discordance.(SFRH/BPD/115169/2016) funded by Fundação
para a Ciência e Tecnologia (FCT); ERDF (European Regional
Development Fund) through the operations: POCI-01-0145-FEDER-029130
('mINSPIRERS—mHealth to measure and improve adherence to medication
in chronic obstructive respiratory diseases—generalisation and evaluation
of gamification, peer support and advanced image processing technologies')
cofunded by the COMPETE2020 (Programa Operacional Competitividade e
Internacionalização), Portugal 2020 and by Portuguese Funds through FCT
(Fundação para a Ciência e a Tecnologia).info:eu-repo/semantics/publishedVersio
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