Cone beam CT evaluation of paranasal sinuses and its use for analysis of the relation between sinus mucosal changes and nasal structures measurements

Orientador: Cinthia Pereira Machado TabchouryTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: Os objetivos neste estudo foram apresentar uma revisão de literatura para discutir o uso da Tomografia Computadorizada de Feixe Cônico (TCFC) para avaliação dos seios paranasais e, por meio de um estudo observacional, relacionar mensurações lineares, angulares e volumétricas de estruturas nasais com alterações muco sinusais dos seios maxilares e avaliar a influência do sexo nas variáveis. Para isso, foram utilizadas 240 imagens de TCFC, divididas em dois grupos: sem alterações sinusais (60 homens e 60 mulheres) e com alterações sinusais (60 homens e 60 mulheres). As imagens foram selecionadas a partir da base de dados do Departamento de Diagnóstico Oral/Área de Radiologia Odontológica da FOP/UNICAMP. Dois avaliadores radiologistas analisaram a angulação do septo, o diâmetro dos óstios dos seios maxilares, o volume do infundíbulo etmoidal e a condição da mucosa sinusal. Mensurações lineares e volumétricas foram realizadas nos softwares OnDemand3DTM (Cybermed, Tustin, CA) e ITK ¿ SNAP (Penn Image Computing and Science Laboratory, Philadelphia, PA), respectivamente. Os resultados foram submetidos à análise estatística; teste Mann¿Whitney foi utilizado para analisar a influência do sexo nas variáveis do estudo e teste de Kruskal-Wallis foi aplicado para verificar a existência de relação entre ausência/presença de alterações sinusais e as variáveis. Os resultados mostraram que o desvio de septo não apresentou relação com a presença de alterações sinusais; os diâmetros ântero-posteriores dos óstios dos seios maxilares não foram relacionados com a presença ou ausência de sinusopatias, porém os diâmetros látero-laterais se apresentaram menores na presença de espessamento mucoso e pólipo; as mulheres sem alteração sinusal apresentaram diâmetros látero-laterais dos óstios dos seios maxilares maiores do que os homens com e sem alteração; os volumes dos infundíbulos etmoidais não apresentaram diferenças na presença/ausência de alterações sinusais. Concluiu-se que pacientes com espessamento mucoso e pólipo nos seios maxilares possuem diâmetros dos óstios reduzidos. As alterações sinusais não possuem relação com a presença do desvio de septo e não afetam o volume do infundíbulo etmoidal. Não houve influência do sexo nas variáveis. A TCFC fornece imagens com grandes detalhes anatômicos e pode ser um método de escolha para a análise do complexo óstio-meatalAbstract: The aim of this study was to expose the literature review in order to discuss the use of Cone Beam Computed Tomography (CBCT) for evaluation the paranasal sinus; correlate the linear, angular and volumetric measurements of nasal structures with maxillary sinus mucosal changes and evaluate the influence of sex on study variables, by an observacional study. For this, 240 CBCT images were used and divided into two groups: without sinus change (60 men and 60 women) and with sinus change (60 men and 60 women). The images were selected from the database of the Department of Oral Diagnosis/Division of Oral Radiology of FOP/UNICAMP. Two radiologists observers evaluated septum deviation, maxillary sinus ostium diameters, ethmoidal infundibulum volume and mucosa conditions. The linear and volumetric measurements were done using the software OnDemand3DTM (Cybermed, Tustin, CA) and ITK-SNAP (Cognitica, Philadelphia, Pa, EUA), respectively. The data was subjected to statistical analysis; the Kruskal-Wallis test was used to verify the existence of a relationship between the absence / presence of sinus changes and other variables analyzed in the study. The Mann-Whitney test was used to analyze the influence of sex and the variables. The results showed that the presence of septal deviation was not related to the presence of sinus change; the presence or absence of sinus change did not influence the anteroposterior ostium diameter, but latero-lateral ostium diameter were smaller in the presence of thickening and polyp; women without sinus change showed latero-lateral ostium diameters greater than men with and without sinus change; ethmoidal infundibulum volume did not show differences in the presence/absence of sinus change. It was concluded that patients with mucosal thickening and polyp in maxillary sinuses have reduced ostium diameters. Maxillary sinus changes do not affect the volume of the infundibulum and are not related with septal deviation. There was no influence of sex on variables. CBCT generates images with great anatomical details and may be an interesting option on the analysis of ostiomeatal complexDoutoradoRadiologia OdontologicaDoutora em Radiologia Odontológica33003033005P9CAPE

Statistical Shape Modelling and Segmentation of the Respiratory Airway

The human respiratory airway consists of the upper (nasal cavity, pharynx) and the lower (trachea, bronchi) respiratory tracts. Accurate segmentation of these two airway tracts can lead to better diagnosis and interpretation of airway-specific diseases, and lead to improvement in the localization of abnormal metabolic or pathological sites found within and/or surrounding the respiratory regions. Due to the complexity and the variability displayed in the anatomical structure of the upper respiratory airway along with the challenges in distinguishing the nasal cavity from non-respiratory regions such as the paranasal sinuses, it is difficult for existing algorithms to accurately segment the upper airway without manual intervention. This thesis presents an implicit non-parametric framework for constructing a statistical shape model (SSM) of the upper and lower respiratory tract, capable of distinct shape generation and be adapted for segmentation. An SSM of the nasal cavity was successfully constructed using 50 nasal CT scans. The performance of the SSM was evaluated for compactness, specificity and generality. An averaged distance error of 1.47 mm was measured for the generality assessment. The constructed SSM was further adapted with a modified locally constrained random walk algorithm to segment the nasal cavity. The proposed algorithm was evaluated on 30 CT images and outperformed comparative state-of-the-art and conventional algorithms. For the lower airway, a separate algorithm was proposed to automatically segment the trachea and bronchi, and was designed to tolerate the image characteristics inherent in low-contrast CT images. The algorithm was evaluated on 20 clinical low-contrast CT from PET-CT patient studies and demonstrated better performance (87.1±2.8 DSC and distance error of 0.37±0.08 mm) in segmentation results against comparative state-of-the-art algorithms

Human identification: an investigation of 3D models of paranasal sinuses to establish a biological profile on a modern UK population

Forensic anthropology traditionally aims to assist law enforcement with human identification by physically examining skeletal remains and assigning a biological profile using various metric and visual methods. These methods are crucial when a body undergoes extreme damage and standard approaches for positive identification are not possible. However, the traditional methods employed by forensic anthropologists were primarily developed from North American reference populations and have demonstrated varying accuracy rates when assigning age, sex, and ancestry to individuals outside of the reference collection. Medical imaging is a valuable source for facilitating empirical research and an accessible gateway for developing novel forensic anthropological methods for analysis including 3D modelling. This is especially critical for the United Kingdom (UK) where biological profiling methods developed from modern UK populations do not currently exist. Researchers have quantified the variability of the paranasal sinuses between individuals and have begun to explore their ability to provide biological information. However, the published literature that addresses these structures in a forensic context presents extremely varied insights and to date there has been no standardisation. This thesis presents research that addresses this gap and introduces a new approach for human identification using 3D models of the paranasal sinuses. The models were produced from a database of modern CT scans provided by University College London Hospital (UCLH), London, UK. Linear measurements and elliptic Fourier coefficients taken from 1,500 three-dimensional models across six ethnic groups assessed by one-way ANOVA and discriminant function analysis showed a range of classification rates with certain rates reaching 75-85.7% (p<0.05) in correctly classifying age and sex according to size and shape. The findings offer insights into the potential for employing CT scans to develop identification methods within the UK and establishes a foundation for using the paranasal sinuses as an attribute for establishing identification of unknown human remains in future crime reconstructions