Magnetic resonance imaging of the vocal tract: techniques and applications

Magnetic resonance (MR) imaging has been used to analyse and evaluate the vocal tract shape through different techniques and with promising results in several fields. Our purpose is to demonstrate the relevance of MR and image processing for the vocal tract study. The extraction of contours of the air cavities allowed the set-up of a number of 3D reconstruction image stacks by means of the combination of orthogonally oriented sets of slices for each articulatory gesture, as a new approach to solve the expected spatial under sampling of the imaging process. In result these models give improved information for the visualization of morphologic and anatomical aspects and are useful for partial measurements of the vocal tract shape in different situations. Potential use can be found in Medical and therapeutic applications as well as in acoustic articulatory speech modelling

Vertebroplastia percutânea por fractura osteoporótica

A Vertebroplastia Percutânea é uma técnica minimamente invasiva relativamente recente, que tem reconhecidas vantagens e aplicações em fracturas compressivas dos corpos vertebrais. Basicamente, consiste na injecção de um Cimento Acrílico no interior do corpo vertebral, e desse modo, minimizar e estabilizar fracturas compressivas dos corpos vertebrais, que são frequentemente de etiologia osteoporótica. Fortemente indicada no tratamento de fracturas incapacitantes, possui como complicação principal o extravasamento do Cimento. Este artigo pretende abordar a técnica, expondo suas indicações, vantagens e complicações mais frequentes. Esta permite reduzir a elevada taxa de morbilidade e impacto económico-social associado à Osteoporose.Percutaneous vertebroplasty is a relatively new minimally invasive technique, which has recognized advantages and applications in vertebral compression fracture. Basically consists of injecting acrylic cement inside the vertebral body, minimizing and stabilizing the compression fractures of vertebral bodies, which are often osteoporotic etiology. Strongly indicated for the treatment of debilitating fractures, has as major complication of cement leakage. This article intends to explain the technique, with their main indications, advantages and complications. This technique allows reducing the high rate of morbidity and socio-economic impact associated with Osteoporosis

Modelling and segmentation of the vocal track during speech production by using deformable models in magnetic resonance images

The first and second authors would like to thank the support of the PhD grants with references SFRH/BD/28817/2006 and SFRH/PROTEC/49517/2009, respectively, from Fundação para a Ciência e Tecnol ogia (FCT). This work was partially done in the scope of the project “Methodologies to Analyze Organs from Complex Medical Images – Applications to Fema le Pelvic Cavity”, wi th reference PTDC/EEA- CRO/103320/2008, financially supported by FCT.Since ancient times, speech production has attracted particularly interest aiming at reaching a deeper understanding of the mechanisms involved by considering both morphological and speech acoustic aspects. The central anatomical aspects and the physiology of the human vocal tract are common to all individuals. However, speech production is an exceptionally complex and individualistic process. Therefore, the modelling of the mechanisms involved in speech production implies the enclosing of adequate flexibility in order to consider individual variations accurately. In this work, the shape of vocal tract in the articulation of some European Portuguese (EP) sounds is evaluated by using deformable models applied in Magnetic Resonance (MR) images. Additionally, the deformable models built are afterwards used to automatically segment the modelled vocal tract in MR images. From the imaging modalities that have been take n into consideration in order to study the vocal tract shape and articulators, Magnetic Resonance Imaging (MRI) has been the most commonly accepted. Actually, the use of MRI allows the study of the entire human vocal tract and, in addition, the quality and resolution of soft-tissues and the use of non-ionizing radiation are key advantages presented by MRI. The deformable model used, commonly known as Point Distribution Model (PDM), was built from a set of training images acquired du ring artificially sustained articulations of 21 EP sounds. In a brief review, one can assert that PDM’s are obtained by a statistical analysis done on the co-ordinates of landmark points that represent the shape to be modelled: after aligning the training shapes, a Principal Component Analysis is performed in order to obtain the model mean shape and the modes of variation relatively to this mean shap e. Combining the geometrical information of the PDM with the grey levels of the landmark points us ed in its building one can build the Active Shape Models (ASM) and the Active Appearance Models (AAM). With these enhanced models is possible to segment the modelled shape in new images in a fully automated way. From the experimental results obtained in this work, one may conclude that the PDM built could efficiently characterize the behaviour of the voca l tract shape during the production of the EP sounds studied with MRI. Furthermore, one can ve rify that the ASM and the AAM built could be used to segment the modelled vocal tract in MR images in a successful manner. Therefore, the deformable models built should be considered towards the efficient and automatic study of the vocal tract during speech production with MRI, in particular for enhanced speech production simulation and speech rehabilitation therapies.Fundação para a Ciência e Tecnologia (FCT

Morfometria do trato vocal por ressonância magnética: simulação de padrões patológicos articulatórios

Introdução - A análise da forma ou morfometria de estruturas anatómicas, como o trato vocal, pode ser efetuada a partir de imagens bidimensionais (2D) como de aquisições volumétricas (3D) de ressonância magnética (RM). Esta técnica de imagem tem vindo a ter uma utilização crescente no estudo da produção da fala. Objetivos - Demonstrar como pode ser efetuada a morfometria do trato vocal a partir da imagem por ressonância magnética e ainda apresentar padrões anatómicos normais durante a produção das vogais [i a u] e dois padrões articulatórios patológicos em contexto simulado. Métodos - As imagens consideradas foram recolhidas a partir de aquisições 2D (Turbo Spin-eco) e 3D (Flash Gradiente-Eco) de RM em quatro sujeitos durante a produção das vogais em estudo; adicionalmente procedeu-se à avaliação de duas perturbações articulatórias usando o mesmo protocolo de RM. A morfometria do trato vocal foi extraída com recurso a técnicas manuais (para extração de cinco medidas articulatórias) e automáticas (para determinação de volumes) de processamento e análise de imagem. Resultados - Foi possível analisar todo o trato vocal, incluindo a posição e a forma dos articuladores, tendo por base cinco medidas descritivas do posicionamento destes órgãos durante a produção das vogais. A determinação destas medições permitiu identificar quais as estratégias mais comummente adotadas na produção de cada som, nomeadamente a postura articulatória e a variação de cada medida para cada um dos sujeitos em estudo. No contexto de voz falada intersujeitos, foi notória a variabilidade nos volumes estimados do trato vocal para cada som e, em especial, o aumento do volume do trato vocal na perturbação articulatória de sigmatismo. Conclusão - A imagem por RM é, sem dúvida, uma técnica promissora no estudo da fala, inócua, não-invasiva e que fornece informação fiável da morfometria do trato vocal.Introduction - The shape or morphologic analysis of anatomical structures, such as the vocal tract can be performed from two-dimensional (2D) or volumetric acquisitions (3D) of magnetic resonance imaging (MRI). This imaging technique has had an increasing use in the study of speech production. Objectives - To determine a method to perform the morphometric analysis of the vocal tract from magnetic resonance imaging; to present anatomical patterns during the normal speech production of some vowels and two pathological articulatory disorders in simulated context. Methods - The image data was collected from 2D (Turbo Spin Echo) and 3D (Flash Gradient Echo) acquisitions of MRI of four subjects during the production of three vowels; in addition, two articulatory disorders were assessed using this imaging protocol. The morphology of the vocal tract was extracted using manual and automatic techniques of image processing and analysis. Results - Based on five articulatory measurements, it was possible to study the entire vocal tract during vowel production, including the position and shape of the articulators involved. Based on these measurements, it was possible to identify the strategies most commonly adopted in the production of each sound, including the articulatory posture and the modification of each measure for the subjects under study. Concerning the voices of the different speakers, the variability in the assessed volumes of the vocal tract for each sound was found, and in particular, the increased vocal tract volume in the articulatory disorder - the sigmatism. Conclusion - MRI is a promising technique for speech production studies, safe, non-invasive and that provides reliable information concerning the morphometric analysis of the vocal tract

Utilização da Imagem por Ressonância Magnética nos Estudos sobre a Produção da Fala

A fala é uma ferramenta única de comunicação, que envolve um conjunto de órgãos que trabalham sincronamente na produção de sons. Os mecanismos envolvidos são complexos, sendo várias as técnicas de estudo da fala, quer do ponto de vista acústico, quer do ponto de vista morfológico. A ressonância magnética tem revelado potencialidades únicas no estudo do tracto vocal, e que são aqui destacadas. O principal objectivo deste estudo é dar a conhecer esta técnica de imagem e demonstrar a sua utilização no estudo da produção da fala, nomeadamente do Português Europeu. Através da recolha e análise de imagens foi possível a obtenção e construção de modelos tridimensionais do tracto vocal nas mais variadas posições articulatórias. Recorrendo a uma técnica de sincronização através de monitorização cardíaca e a aquisições de imagem ultra-rápidas foi possível também a captação dinâmica por sub-amostragem e a observação dos movimentos articulatórios envolvidos durante a produção de três sílabas. A caracterização morfológica e dinâmica do tracto vocal com base nas imagens de ressonância magnética é, face aos resultados obtidos, fiável e deveras importante para o conhecimento deste mecanismo. Para além disso, a informação obtida desperta um interesse multidisciplinar e aplicações diversas com potencialidades marcantes face aos esperados avanços tecnológicos desta técnica de imagem

Three-dimensional visualization of teeth by magnetic resonance imaging during speech

Teeth morphology and oral cavity visualization through imaging techniques enables an accurate vocal tract assessment in speech research, especially when by Magnetic Resonance Imaging (MRI)info:eu-repo/semantics/publishedVersio

Arrest in ciliated cell expansion on the bronchial lining of adult rats caused by chronic exposure to industrial noise

Workers chronically exposed to high-intensity/low-frequency noise at textile plants show increased frequency of respiratory infections. This phenomenon prompted the herein investigation on the cytology of the bronchial epithelium of Wistar rats submitted to textile noise. Workplace noise from a cotton-mill room of a textile factory was recorded and reproduced in a sound-insulated animal room. The Wistar rats were submitted to a weekly schedule of noise treatment that was similar to that of the textile workers (8 h/day, 5 days/week). Scanning electron microscopy (SEM) was used to compare the fine morphology of the inner surface of the bronchi in noise-exposed and control rats. SEM quantitative cytology revealed that exposure to noise for 5-7 months caused inhibition in the natural expansion of the area occupied by ciliated cells on the bronchial epithelium as adult rats grow older. This difference between noise-exposed and age-matched control rats was statistically significant (P<0.05) and documents that the cytology of the rat bronchial epithelium is mildly altered by noise exposure. The decrease in the area of bronchial cilia may impair the mucociliar clearance of the respiratory airways and, thus, increase vulnerability to respiratory infection

Atrial fibrosis and decreased connexin 43 in rat hearts after exposure to high-intensity infrasound

Background: Noise is an important environmental risk factor. Industrial environments are rich in high-intensity infrasound (hi-IFS), which we have found to induce myocardial and coronary perivascular fibrosis in rats. The effects of exposure to IFS on the ventricles have been studied, but not on the atria. We hypothesized that rats exposed to hi-IFS develop atrial remodeling involving fibrosis and connexin 43, which we sought to evaluate. Material and methods: Seventy-two Wistar rats, half exposed to hi-IFS (120 dB, < 20 Hz) during a maximum period of 12 weeks and half age-matched controls, were studied. Atrial fibrosis was analyzed by Chromotropeaniline blue staining. The immunohistochemical evaluation of Cx43 was performed using the polyclonal antibody connexin-43 m diluted 1:1000 at 4 degrees C overnight. Digitized images were obtained with an optical microscope using 400 x magnifications. The measurements were performed using image J software. A two-way ANOVA model was used to compare the groups. Results: The mean values of the ratio "atrial fibrosis / cardiomyocytes" increased to a maximum of 0.1095 +/- 0,04 and 0.5408 +/- 0,01, and of the ratio "CX43 / cardiomyocytes" decreased to 0.0834 +/- 0,03 and 0.0966 +/- 0,03, respectively in IFS-exposed rats and controls. IFS-exposed rats exhibited a significantly higher ratio of fibrosis (p < .001) and lower ratio of Cx43 (p = .009). Conclusion: High-intensity infrasound exposure leads to an increase in atrial interstitial fibrosis and a decrease in connexin 43 in rat hearts. This finding reinforces the need for further experimental and clinical studies concerning the effects of exposure to infrasound

Inter-speaker speech variability assessment using statistical deformable models from 3.0 Tesla magnetic resonance images

The morphological and dynamic characterisation of the vocal tract during speech production has been gaining greater attention due to the motivation of the latest improvements in magnetic resonance (MR) imaging; namely, with the use of higher magnetic fields, such as 3.0 Tesla. In this work, the automatic study of the vocal tract from 3.0 Tesla MR images was assessed through the application of statistical deformable models. Therefore, the primary goal focused on the analysis of the shape of the vocal tract during the articulation of European Portuguese sounds, followed by the evaluation of the results concerning the automatic segmentation, i.e. identification of the vocal tract in new MR images. In what concerns speech production, this is the first attempt to automatically characterise and reconstruct the vocal tract shape of 3.0 Tesla MR images by using deformable models; particularly, by using active and appearance shape models. The achieved results clearly evidence the adequacy and advantage of the automatic analysis of the 3.0 Tesla MR images of these deformable models in order to extract the vocal tract shape and assess the involved articulatory movements. These achievements are mostly required, for example, for a better knowledge of speech production, mainly of patients suffering from articulatory disorders, and to build enhanced speech synthesizer models.info:eu-repo/semantics/publishedVersio