Validation of a magnetic resonance imaging-based auto-contouring software tool for gross tumour delineation in head and neck cancer radiotheraphy planning

To perform statistical validation of a newly developed magnetic resonance imaging (MRI) auto-contouring software tool for gross tumour volume (GTV) delineation in head and neck tumours to assist in radiotherapy planning. Axial MRI baseline scans were obtained for 10 oropharyngeal and laryngeal cancer patients. GTV was present on 102 axial slices and auto-contoured using the modified fuzzy c-means clustering integrated with level set method (FCLSM). Peer reviewed (C-gold) manual contours were used as the reference standard to validate auto-contoured GTVs (C-auto) and mean manual contours (C-manual) from 2 expert clinicians (C1 and C2). Multiple geometrical metrics, including Dice Similarity Coefficient (DSC) were used for quantitative validation. A DSC ≥0.7 was deemed acceptable. Inter-and intra-variabilities amongst the manual contours were also validated. The 2-dimension (2D) contours were then reconstructed in 3D for GTV volume calculation, comparison and 3D visualisation. The mean DSC between C-gold and C-auto was 0.79. The mean DSC bet ween C-gold and C-manual was 0.79 and that between C1 and C2 was 0.80. The average time for GTV auto-contouring per patient was 8 minutes (range 6-13mins; mean 45seconds per axial slice) compared to 15 minutes (range 6-23mins; mean 88 seconds per axial slice) for C1. The average volume concordance between C-gold and C-auto volumes was 86. 51% compared to 74.16% between C-gold and C-manual. The average volume concordance between C1 and C2 volumes was 86.82%. This newly-designed MRI-based auto-contouring software tool shows initial acceptable results in GTV delineation of oropharyngeal and laryngeal tumours using FCLSM. This auto-contouring software tool may help reduce inter-and intra- variability and can assist clinical oncologists with time-consuming, complex radiotherapy planning

Data-Driven Critical Tract Variable Determination for European Portuguese

Technologies, such as real-time magnetic resonance (RT-MRI), can provide valuable information to evolve our understanding of the static and dynamic aspects of speech by contributing to the determination of which articulators are essential (critical) in producing specific sounds and how (gestures). While a visual analysis and comparison of imaging data or vocal tract profiles can already provide relevant findings, the sheer amount of available data demands and can strongly profit from unsupervised data-driven approaches. Recent work, in this regard, has asserted the possibility of determining critical articulators from RT-MRI data by considering a representation of vocal tract configurations based on landmarks placed on the tongue, lips, and velum, yielding meaningful results for European Portuguese (EP). Advancing this previous work to obtain a characterization of EP sounds grounded on Articulatory Phonology, important to explore critical gestures and advance, for example, articulatory speech synthesis, entails the consideration of a novel set of tract variables. To this end, this article explores critical variable determination considering a vocal tract representation aligned with Articulatory Phonology and the Task Dynamics framework. The overall results, obtained considering data for three EP speakers, show the applicability of this approach and are consistent with existing descriptions of EP sounds

A shape base framework to segmentation of tongue contours from MRI data

ISBN: 978-1-4244-4296-6 ISSN: 1520-6149International audienceWe propose a shape-based variational framework to curve evolution for the segmen tation of tongue contours from MRI mid-sagittal images. In particular, we first build a PCA model on tongue contours of different articulations of a reference s peaker, and use it as shape priors. The parameters of the curve representation a re then manipulated to minimize an objective function. The designed energy integ rates both global and local image information. The global term extracts roughly the object in the whole image domain; while the local term improves precision in side a small neighborhood around the contour. Promising results and comparisons with other approaches demonstrate the efficiency of our new model

On the role of oral configurations in European Portuguese nasal vowels

The characterisation of nasal vowels is not only a question ofstudying velar aperture. Recent work shows that oropharyngeal articulatory adjustments enhance the acoustics of nasal couplingor, at least, magnify differences between oral/nasal vowel congeners. Despite preliminary studies on the oral configurations of nasal vowels, for European Portuguese, a quantitative analysis is missing, particularly one to be applied systematically to a desirably large number of speakers. The main objective ofthis study is to adapt and extend previous methodological advances for the analysis of MRI data to further investigate: howvelar changes affect oral configurations; the changes to the articulators and constrictions when compared with oral counteparts; and the closest oral counterpart. High framerate RT-MRIimages (50fps) are automatically processed to extract the vocal tract contours and the position/configuration for the different articulators. These data are processed by evolving a quantitative articulatory analysis framework, previously proposed by the authors, extended to include information regarding constrictions (degree and place) and nasal port. For this study, while the analysis of data for more speakers is ongoing, we considered a set of two EP native speakers and addressed the study of oral and nasal vowels mainly in the context of stop consonants