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

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

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

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

Preprocessing of Magnetic Resonance Images with Multiple Sclerosis Lesions

According to the World Health Organization, it is estimated that multiple sclerosis (MS) affects around 2.5 million people worldwide and more than 5000 in Portugal. Multiple sclerosis is an inflammatory, demyelinating, idiopathic, and often disabling central nervous system disease that affects the white matter diagnosed in young adults and predominantly affects womens. Multiple sclerosis is the most common neurological disorder with unexplained causes and major repercussions in the lives of patients, causing the active search for answers by the researchers. Although the disease cannot be cured or prevented at this time, the available treatments only reduce its severity and delay its progression. In recent years, there has been a major development of image processing and analysis techniques in order to facilitate early diagnosis and suitable treatment. In general, images acquired by imaging devices and specialized techniques require transformations and enhancements to make them more suitable in order to extract as much information as desired with greater efficiency. Several authors, have described techniques of image preprocessing and segmentation of MS lesions, making evident the advantages of such computational tools. In this work, different preprocessing algorithms were applied in order to perform the brain extraction from resonance magnetic (RM) images for their easier further analysis.info:eu-repo/semantics/publishedVersio

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

Segmentation of tongue shapes during vowel production in magnetic resonance images based on statistical modelling

Quantification of the anatomic and functional aspects of the tongue is pertinent to analyse the mechanisms involved in speech production. Speech requires dynamic and complex articulation of the vocal tract organs, and the tongue is one of the main articulators during speech production. Magnetic resonance imaging has been widely used in speech-related studies. Moreover, the segmentation of such images of speech organs is required to extract reliable statistical data. However, standard solutions to analyse a large set of articulatory images have not yet been established. Therefore, this article presents an approach to segment the tongue in two-dimensional magnetic resonance images and statistically model the segmented tongue shapes. The proposed approach assesses the articulator morphology based on an active shape model, which captures the shape variability of the tongue during speech production. To validate this new approach, a dataset of mid-sagittal magnetic resonance images acquired from four subjects was used, and key aspects of the shape of the tongue during the vocal production of relevant European Portuguese vowels were evaluated

DBD treatment of diacetate, polyamide, polyester, acrylic and wool fibres and competitive dyeing with different dye classes

In this work we present a study of a DBD plasma treatment of five different fibres (diacetate, polyamide, polyester, acrylic and wool), using a dielectric barrier discharge running with different dosages in air at atmospheric pressure. Based on the results above, the dosage around 600 W.min/m2 has been found to produce uniform wettability in tested materials. The experiments were conducted to determine the effects of the DBD treatment on the measured changes in surface wettability, morphology and chemical composition. After DBD plasma treatment, dyeing experiments were carried out in order to evaluate colour strength (K/S) in the samples with and without treatment and high improvement of tintorial properties has been detected in a significant number of the trials

Extraction and purification of phycobiliproteins from algae and their applications

Microalgae, macroalgae and cyanobacteria are photosynthetic microorganisms, prokaryotic or eukaryotic, living in saline or freshwater environments. These have been recognized as valuable carbon sources, able to be used for food, feed, chemicals, and biopharmaceuticals. From the range of valuable compounds produced by these cells, some of the most interesting are the pigments, including chlorophylls, carotenoids, and phycobiliproteins. Phycobiliproteins are photosynthetic light-harvesting and water-soluble proteins. In this work, the downstream processes being applied to recover fluorescent proteins from marine and freshwater biomass are reviewed. The various types of biomasses, namely macroalgae, microalgae, and cyanobacteria, are highlighted and the solvents and techniques applied in the extraction and purification of the fluorescent proteins, as well as their main applications while being fluorescent/luminescent are discussed. In the end, a critical perspective on how the phycobiliproteins business may benefit from the development of cost-effective downstream processes and their integration with the final application demands, namely regarding their stability, will be provided.publishe