962 research outputs found
Models and Analysis of Vocal Emissions for Biomedical Applications
The International Workshop on Models and Analysis of Vocal Emissions for Biomedical Applications (MAVEBA) came into being in 1999 from the particularly felt need of sharing know-how, objectives and results between areas that until then seemed quite distinct such as bioengineering, medicine and singing. MAVEBA deals with all aspects concerning the study of the human voice with applications ranging from the newborn to the adult and elderly. Over the years the initial issues have grown and spread also in other fields of research such as occupational voice disorders, neurology, rehabilitation, image and video analysis. MAVEBA takes place every two years in Firenze, Italy. This edition celebrates twenty-two years of uninterrupted and successful research in the field of voice analysis
An Overview of Breath Phase Detection – Techniques & Applications
The main aim of this study is to provide an overview on the state of the art techniques (acoustic and nonacoustic approaches) involved in breath phase detection and to highlight applications where breath phase detection is vital. Both acoustic and non-acoustic approaches are summarized in detail. The non-acoustic approach involves placement of sensors or flow measurement devices to estimate the breath phases, whereas the acoustic approach involves the use of sophisticated signal processing methods on respiratory sounds to detect breath phases. This article also briefly discusses the advantages and disadvantages of the acoustic and non-acoustic approaches of breath phase detection. The literature reveals that recent advancements in computing technology open avenues for researchers to apply sophisticated signal processing techniques and artificial intelligence algorithms to detect the breath phases in a non-invasive way. Future works that can be implemented after detecting the breath phases are also highlighted in this article
An Overview Of Breath Phase Detection – Techniques & Applications
The main aim of this study is to provide an overview on the state of the art techniques (acoustic and non-acoustic approaches) involved in breath phase detection and to highlight applications where breath phase detection is vital. Both acoustic and non-acoustic approaches are summarized in detail. The non-acoustic approach involves placement of sensors or flow measurement devices to estimate the breath phases, whereas the acoustic approach involves the use of sophisticated signal processing methods on respiratory sounds to detect breath phases. This article also briefly discusses the advantages and disadvantages of the acoustic and non-acoustic approaches of breath phase detection. The literature reveals that recent advancements in computing technology open avenues for researchers to apply sophisticated signal processing techniques and artificial intelligence algorithms to detect the breath phases in a non-invasive way. Future works that can be implemented after detecting the breath phases are also highlighted in this article
Models and Analysis of Vocal Emissions for Biomedical Applications
The MAVEBA Workshop proceedings, held on a biannual basis, collect the scientific papers presented both as oral and poster contributions, during the conference. The main subjects are: development of theoretical and mechanical models as an aid to the study of main phonatory dysfunctions, as well as the biomedical engineering methods for the analysis of voice signals and images, as a support to clinical diagnosis and classification of vocal pathologies
Models and Analysis of Vocal Emissions for Biomedical Applications
The MAVEBA Workshop proceedings, held on a biannual basis, collect the scientific papers presented both as oral and poster contributions, during the conference. The main subjects are: development of theoretical and mechanical models as an aid to the study of main phonatory dysfunctions, as well as the biomedical engineering methods for the analysis of voice signals and images, as a support to clinical diagnosis and classification of vocal pathologies
Navigation system based in motion tracking sensor for percutaneous renal access
Tese de Doutoramento em Engenharia BiomédicaMinimally-invasive kidney interventions are daily performed to diagnose and treat several renal
diseases. Percutaneous renal access (PRA) is an essential but challenging stage for most of these
procedures, since its outcome is directly linked to the physician’s ability to precisely visualize and
reach the anatomical target.
Nowadays, PRA is always guided with medical imaging assistance, most frequently using X-ray
based imaging (e.g. fluoroscopy). Thus, radiation on the surgical theater represents a major risk to
the medical team, where its exclusion from PRA has a direct impact diminishing the dose exposure
on both patients and physicians.
To solve the referred problems this thesis aims to develop a new hardware/software framework
to intuitively and safely guide the surgeon during PRA planning and puncturing.
In terms of surgical planning, a set of methodologies were developed to increase the certainty of
reaching a specific target inside the kidney. The most relevant abdominal structures for PRA were
automatically clustered into different 3D volumes. For that, primitive volumes were merged as a local
optimization problem using the minimum description length principle and image statistical
properties. A multi-volume Ray Cast method was then used to highlight each segmented volume.
Results show that it is possible to detect all abdominal structures surrounding the kidney, with the
ability to correctly estimate a virtual trajectory.
Concerning the percutaneous puncturing stage, either an electromagnetic or optical solution
were developed and tested in multiple in vitro, in vivo and ex vivo trials. The optical tracking solution
aids in establishing the desired puncture site and choosing the best virtual puncture trajectory.
However, this system required a line of sight to different optical markers placed at the needle base,
limiting the accuracy when tracking inside the human body. Results show that the needle tip can
deflect from its initial straight line trajectory with an error higher than 3 mm. Moreover, a complex
registration procedure and initial setup is needed.
On the other hand, a real-time electromagnetic tracking was developed. Hereto, a catheter
was inserted trans-urethrally towards the renal target. This catheter has a position and orientation
electromagnetic sensor on its tip that function as a real-time target locator. Then, a needle integrating a similar sensor is used. From the data provided by both sensors, one computes a virtual puncture
trajectory, which is displayed in a 3D visualization software. In vivo tests showed a median renal and
ureteral puncture times of 19 and 51 seconds, respectively (range 14 to 45 and 45 to 67 seconds).
Such results represent a puncture time improvement between 75% and 85% when comparing to
state of the art methods.
3D sound and vibrotactile feedback were also developed to provide additional information about
the needle orientation. By using these kind of feedback, it was verified that the surgeon tends to
follow a virtual puncture trajectory with a reduced amount of deviations from the ideal trajectory,
being able to anticipate any movement even without looking to a monitor. Best results show that 3D
sound sources were correctly identified 79.2 ± 8.1% of times with an average angulation error of
10.4º degrees. Vibration sources were accurately identified 91.1 ± 3.6% of times with an average
angulation error of 8.0º degrees.
Additionally to the EMT framework, three circular ultrasound transducers were built with a needle
working channel. One explored different manufacture fabrication setups in terms of the piezoelectric
materials, transducer construction, single vs. multi array configurations, backing and matching
material design. The A-scan signals retrieved from each transducer were filtered and processed to
automatically detect reflected echoes and to alert the surgeon when undesirable anatomical
structures are in between the puncture path. The transducers were mapped in a water tank and
tested in a study involving 45 phantoms. Results showed that the beam cross-sectional area
oscillates around the ceramics radius and it was possible to automatically detect echo signals in
phantoms with length higher than 80 mm.
Hereupon, it is expected that the introduction of the proposed system on the PRA procedure,
will allow to guide the surgeon through the optimal path towards the precise kidney target, increasing
surgeon’s confidence and reducing complications (e.g. organ perforation) during PRA. Moreover, the
developed framework has the potential to make the PRA free of radiation for both patient and surgeon
and to broad the use of PRA to less specialized surgeons.Intervenções renais minimamente invasivas são realizadas diariamente para o tratamento e
diagnóstico de várias doenças renais. O acesso renal percutâneo (ARP) é uma etapa essencial e
desafiante na maior parte destes procedimentos. O seu resultado encontra-se diretamente
relacionado com a capacidade do cirurgião visualizar e atingir com precisão o alvo anatómico.
Hoje em dia, o ARP é sempre guiado com recurso a sistemas imagiológicos, na maior parte
das vezes baseados em raios-X (p.e. a fluoroscopia). A radiação destes sistemas nas salas cirúrgicas
representa um grande risco para a equipa médica, aonde a sua remoção levará a um impacto direto
na diminuição da dose exposta aos pacientes e cirurgiões.
De modo a resolver os problemas existentes, esta tese tem como objetivo o desenvolvimento
de uma framework de hardware/software que permita, de forma intuitiva e segura, guiar o cirurgião
durante o planeamento e punção do ARP.
Em termos de planeamento, foi desenvolvido um conjunto de metodologias de modo a
aumentar a eficácia com que o alvo anatómico é alcançado. As estruturas abdominais mais
relevantes para o procedimento de ARP, foram automaticamente agrupadas em volumes 3D, através
de um problema de optimização global com base no princípio de “minimum description length” e
propriedades estatísticas da imagem. Por fim, um procedimento de Ray Cast, com múltiplas funções
de transferência, foi utilizado para enfatizar as estruturas segmentadas. Os resultados mostram que
é possível detetar todas as estruturas abdominais envolventes ao rim, com a capacidade para
estimar corretamente uma trajetória virtual.
No que diz respeito à fase de punção percutânea, foram testadas duas soluções de deteção
de movimento (ótica e eletromagnética) em múltiplos ensaios in vitro, in vivo e ex vivo. A solução
baseada em sensores óticos ajudou no cálculo do melhor ponto de punção e na definição da melhor
trajetória a seguir. Contudo, este sistema necessita de uma linha de visão com diferentes
marcadores óticos acoplados à base da agulha, limitando a precisão com que a agulha é detetada
no interior do corpo humano. Os resultados indicam que a agulha pode sofrer deflexões à medida
que vai sendo inserida, com erros superiores a 3 mm.
Por outro lado, foi desenvolvida e testada uma solução com base em sensores
eletromagnéticos. Para tal, um cateter que integra um sensor de posição e orientação na sua ponta, foi colocado por via trans-uretral junto do alvo renal. De seguida, uma agulha, integrando um sensor
semelhante, é utilizada para a punção percutânea. A partir da diferença espacial de ambos os
sensores, é possível gerar uma trajetória de punção virtual. A mediana do tempo necessário para
puncionar o rim e ureter, segundo esta trajetória, foi de 19 e 51 segundos, respetivamente
(variações de 14 a 45 e 45 a 67 segundos). Estes resultados representam uma melhoria do tempo
de punção entre 75% e 85%, quando comparados com o estado da arte dos métodos atuais.
Além do feedback visual, som 3D e feedback vibratório foram explorados de modo a fornecer
informações complementares da posição da agulha. Verificou-se que com este tipo de feedback, o
cirurgião tende a seguir uma trajetória de punção com desvios mínimos, sendo igualmente capaz
de antecipar qualquer movimento, mesmo sem olhar para o monitor. Fontes de som e vibração
podem ser corretamente detetadas em 79,2 ± 8,1% e 91,1 ± 3,6%, com erros médios de angulação
de 10.4º e 8.0 graus, respetivamente.
Adicionalmente ao sistema de navegação, foram também produzidos três transdutores de
ultrassom circulares com um canal de trabalho para a agulha. Para tal, foram exploradas diferentes
configurações de fabricação em termos de materiais piezoelétricos, transdutores multi-array ou
singulares e espessura/material de layers de suporte. Os sinais originados em cada transdutor
foram filtrados e processados de modo a detetar de forma automática os ecos refletidos, e assim,
alertar o cirurgião quando existem variações anatómicas ao longo do caminho de punção. Os
transdutores foram mapeados num tanque de água e testados em 45 phantoms. Os resultados
mostraram que o feixe de área em corte transversal oscila em torno do raio de cerâmica, e que os
ecos refletidos são detetados em phantoms com comprimentos superiores a 80 mm.
Desta forma, é expectável que a introdução deste novo sistema a nível do ARP permitirá
conduzir o cirurgião ao longo do caminho de punção ideal, aumentado a confiança do cirurgião e
reduzindo possíveis complicações (p.e. a perfuração dos órgãos). Além disso, de realçar que este
sistema apresenta o potencial de tornar o ARP livre de radiação e alarga-lo a cirurgiões menos
especializados.The present work was only possible thanks to the support by the Portuguese Science and
Technology Foundation through the PhD grant with reference SFRH/BD/74276/2010 funded by
FCT/MEC (PIDDAC) and by Fundo Europeu de Desenvolvimento Regional (FEDER), Programa
COMPETE - Programa Operacional Factores de Competitividade (POFC) do QREN
A computer based analysis of the effects of rhythm modification on the intelligibility of the speech of hearing and deaf subjects
The speech of profoundly deaf persons often exhibits acquired unnatural rhythms, or a random pattern of rhythms. Inappropriate pause-time and speech-time durations are common in their speech. Specific rhythm deficiencies include abnormal rate of syllable utterance, improper grouping, poor timing and phrasing of syllables and unnatural stress for accent and emphasis. Assuming that temporal features are fundamental to the naturalness of spoken language, these abnormal timing patterns are often detractive. They may even be important factors in the decreased intelligibility of the speech. This thesis explores the significance of temporal cues in the rhythmic patterns of speech. An analysis-synthesis approach was employed based on the encoding and decoding of speech by a tandem chain of digital computer operations. Rhythm as a factor in the speech intelligibility of deaf and normal-hearing subjects was investigated. The results of this study support the general hypothesis that rhythm and rhythmic intuition are important to the perception of speech
Simulation methods and tissue property models for non-invasive transcranial focused ultrasound surgery
Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2005.Includes bibliographical references.Many brain tumors are localized deeply and are currently surgically inaccessible without causing severe damage to the overlying structures of the brain. The current spectrum of non-invasive methods for treating such tumors includes radiotherapy, which requires exposure to ionizing radiation, and chemotherapy, which is systemically toxic. However, these tumors may also potentially be attacked by focusing highly intense ultrasound onto them. Focused ultrasound surgery is without the side effects of radiotherapy and chemotherapy, and the therapeutic effect of ultrasound therapy can be monitored in real- time using the proton chemical shift MRI technique. However, in order for brain tumors to be treated non-invasively, the ultrasound must be focused onto the targeted brain tissue through the intact cranium. Transcranial focusing of ultrasound is a longstanding and difficult problem as skull is a highly heterogeneous material. As the ultrasound field propagates through the bones of the skull, it undergoes substantatial distortion due to the variations in density and speed of sound therein. There is substantial individual variation in skull size, thickness and composition. Furthermore, the acoustic attenuation coefficient in bone is high, so the skull may also be heated by the ultrasound propagating through it. This thesis contains novel simulation techniques for analyzing transcranial acoustic propagation and for analyzing the temperature changes so produced in the brain, skull and scalp. These techniques have also been applied to modeling non-invasive treatment of the liver, and to producing therapeutic ultrasound fields that harness non-linear acoustic effects advantageously.(cont.) The thesis also contains unified models for the speed of sound and the acoustic attenuation coeffiecient in human skull. These models were generated by combining genetic optimization algorithms, acoustic propagation modeling and empirical measurement of intracranial ultrasound fields; they are valid across the full range of trabecular and cortical cranial bone.by Christopher W. Connor.Ph.D
A novel automatic method for monitoring Tourette motor tics through a wearable device
The aim of this study was to propose a novel automatic
method for quantifying motor-tics caused by the Tourette
Syndrome (TS). In this preliminary report, the feasibility
of the monitoring process was tested over a series of standard
clinical trials in a population of 12 subjects affected by TS.
A wearable instrument with an embedded three-axial accelerometer was used to detect and classify motor tics during
standing and walking activities. An algorithm was devised to
analyze acceleration data by: eliminating noise; detecting
peaks connected to pathological events; and classifying intensity
and frequency of motor tics into quantitative scores.
These indexes were compared with the video-based ones provided
by expert clinicians, which were taken as the goldstandard.
Sensitivity, specificity, and accuracy of tic detection
were estimated, and an agreement analysis was performed
through the least square regression and the Bland-Altman
test. The tic recognition algorithm showed sensitivity 5
80.8% 6 8.5% (mean 6 SD), specificity 5 75.8% 6 17.3%,
and accuracy 5 80.5% 6 12.2%. The agreement study
showed that automatic detection tended to overestimate the
number of tics occurred. Although, it appeared this may be
a systematic error due to the different recognition principles
of the wearable and video-based systems. Furthermore,
there was substantial concurrency with the gold-standard in
estimating the severity indexes. The proposed methodology
gave promising performances in terms of automatic motortics
detection and classification in a standard clinical context.
The system may provide physicians with a quantitative
aid for TS assessment. Further developments will focus on
the extension of its application to everyday long-term monitoring
out of clinical environments
Models and analysis of vocal emissions for biomedical applications: 5th International Workshop: December 13-15, 2007, Firenze, Italy
The MAVEBA Workshop proceedings, held on a biannual basis, collect the scientific papers presented both as oral and poster contributions, during the conference. The main subjects are: development of theoretical and mechanical models as an aid to the study of main phonatory dysfunctions, as well as the biomedical engineering methods for the analysis of voice signals and images, as a support to clinical diagnosis and classification of vocal pathologies. The Workshop has the sponsorship of: Ente Cassa Risparmio di Firenze, COST Action 2103, Biomedical Signal Processing and Control Journal (Elsevier Eds.), IEEE Biomedical Engineering Soc. Special Issues of International Journals have been, and will be, published, collecting selected papers from the conference
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