Em casos de investigação criminal, a determinação do tempo de morte pode inocentar ou culpar algum suspeito. Atualmente, os estudos publicados relacionados ao advento da autópsia virtual não consideram a possibilidade da utilização dos exames complementares de imagem como auxílio à estimativa do intervalo postmortem, sendo esta uma das principais motivações para a realização do presente estudo, já que a tomografia computadorizada é excelente método de medida de densidade. Diante desse cenário, o objetivo do trabalho foi aprimorar a estimativa do intervalo postmortem por meio da avaliação tomográfica das hipóstases viscerais torácicas. Foi realizado estudo prospectivo observacional com dados obtidos de 23 corpos de pacientes de ambos os sexos que foram encaminhados ao Serviço de Verificação de Óbitos da Capital São Paulo. Foram obtidos cortes tomográficos do segmento torácico de modo sequencial utilizando-se o tomógrafo SOMATOM® Emotion syngo CT 2012E, com intervalo de uma hora entre os exames, a fim de permitir a análise das modificações de densidade das hipóstases ao longo do tempo. Na janela de mediastino, foram selecionados os átrios direito e esquerdo para obtenção das medidas de densidade tecidual média. Foi possível concluir que a maioria das hipóstases pulmonares se estabiliza entre 8 e 12 horas e as hipóstases intracardíacas em torno de 12 horas. Além disso, o modelo estatístico de Mitscherlich pode ser utilizado para descrever o comportamento da hipóstase em função do intervalo de morte decorrido / In cases of criminal investigation, the determination of the time of death can acquit or condemn a suspect. Currently, the published studies related to the raising of the postmortem CT do not consider the possibility of using the complementary image exams as support to the estimate of the postmortem interval, being that one of the main motivations to the execution of the present study, once the multislice computed tomography is an excellent method of measure of density. In this scenery, the goal of this study was to improve the precision of the determination of the time of death through the tomographic evaluation of the visceral thoracic hypostasis. A prospective study was performed with data obtained from 23 bodies of patients, which were forward to the autopsy center of the city of São Paulo. Tomographic images of thorax were obtained sequentially, by using SOMATOM® Emotion syngo CT 2012E, with intervals of one hour each one between the exams, in order to allow the analysis of the modifications of the density of the hypostasis over time. In the mediastinum window, the right and left atrium were selected in order to obtain the measures of the average organ density. It was possible to conclude that the majority of the pulmonary hypostasis would stabilize between 8 and 12 hours and the intracardiac hypostasis around 12 hours. Furthermore, the statistical model of Mitscherlich can be used to describe the behavior of the images according to the postmortem interval

Os molares superiores são um dos grupos dentários que mais recebem tratamentos endodônticos e apresentam grande complexidade anatômica nos seus sistemas de canais radiculares. A presença de um canal mesiopalatino (MP) na raiz mesiovestibular é um achado bastante comum e a sua não detecção está relacionada com um alto índice de insucessos na terapia endodôntica. Recentemente, a tomografia computadorizada de feixe cônico (TCFC) vem ganhando destaque na avaliação do canal MP pela sua capacidade de fornecer informações detalhadas e em três dimensões, sendo considerada o melhor método de imagem para essa investigação in vivo. Desta forma, o objetivo desta tese foi pesquisar a prevalência e simetria do número de canais da raiz mesiovestibular em primeiros molares superiores homólogos, por meio da TCFC, assim como, analisar o uso dos filtros de refinamento de imagem para esta investigação. Para o primeiro objetivo, desenvolveu-se uma pesquisa com 264 pacientes possuindo o primeiro molar superior bilateralmente. Foi encontrada simetria em 78,79% dos pacientes, sendo que o canal MP esteve presente bilateralmente em 67,42%. Do total de 528 dentes avaliados, 78% apresentaram o canal MP não havendo correlação da sua presença com sexo e faixa etária (p > 0,05). Para o segundo objetivo, 30 exames de TCFC foram avaliados com cinco diferentes filtros (Original, Smooth, Sharpen, Sharpen Mild, Angio Sharpen Low e Angio Sharpen High) além das imagens originais (sem filtro). Todos os filtros apresentaram altos índices de acurácia (> 83,3%), sensibilidade (> 90%) e especificidade (> 62%), sem diferença estatística (p > 0,05). Entretanto, quando o nível de certeza foi avaliado, os filtros Angio Sharpen High e Sharpen apresentaram os piores resultados, com diferença significativa para as imagens Originais (p <0,05). Os resultados das pesquisas conduzidas permitem concluir que o canal MP é uma condição altamente prevalente e a sua simetria bilateral é frequente. O emprego de filtros de imagem da TCFC não influenciou a detecção do canal MP, entretanto os filtros de maior realce devem ser evitados pois reduzem a certeza do diagnóstico. / The upper molars are the dental group that most receives endodontic treatments and presents great anatomical complexity of their root canal systems. The presence of a second mesiobuccal canal (MB2) is a common finding and its non-detection is related to a high failure rate in endodontic therapy. Recently, cone-beam computed tomography (CBCT) has been highlighted in the MB2 evaluation for its ability to provide detailed and three-dimensional information, and is considered the best imaging method for such investigation in vivo. Thus, the aim of this thesis was to investigate the prevalence and symmetry of the root canal numbers from the mesiobuccal root of first homologous upper molars, as well as to evaluate the use of CBCT image filters for that purpose. For the first objective, a research was developed with 264 patients having the first upper molar bilaterally. Symmetry was found in 78.79% patients, and the MB2 was bilaterally present in 67.42%. Out the total of 528 teeth evaluated, 78% presented the MB2, with no correlation with sex and age group (p > 0.05). For the second objective, 30 CBCT scans were evaluated with five different filters (Original, Smooth, Sharpen, Sharpen Mild, Angio Sharpen Low and Angio Sharpen High) in addition to the original images (none filter). All filters presented high levels of accuracy (> 83.3%), sensitivity (> 90%) and specificity (> 62%), with no statistical difference (p > 0.05). However, when the level of certainty was evaluated, Angio Sharpen High and Sharpen filters presented the worst results, with significant difference for Original images (p < 0.05). The results of the conducted studies allow us to conclude that the MB2 is a highly prevalent condition and its bilateral simmetry is frequent. The use of CBCT image filters did not influence the MB2 detection, however higher enhancement filters should be avoided because they reduce the certainty of the diagnosis.

O presente estudo teve por objetivo avaliar comparativamente o emprego de tomografias e cortes transversais na quantificação de material obturador endodôntico remanescente à desobturação e repreparo dos canais radiculares. Para tal, 32 dentes preparados, obturados e após periodo necessário para o ennvelhecimento do cimento obturador foram desobturados e repreparados. Os espécimes tiveram o conteúdo de material obturador remanescente avaliado por diferentes métodos: aferição em tomógrafo computadorizado de múltiplos detectores e aferição em software Leica Qwin. Inicialmente foram medidos os volumes de material obturador remanescente no tomógrafo computadorizado com os espécimes ainda íntegros. Em seqüência, realizou-se nos mesmos cortes transversais com espessura de 1mm permitindo assim aferição: do volume em tomógrafo computadorizado após o corte; das áreas de material remanescente em cada corte com auxílio do software Leica Qwin. Para que fosse possível a comparação dos métodos, os valores de área foram utilizados para cálculo do volume de material remanescente em cada espécime através da fórmula do volume do cone truncado. Os resultados obtidos foram submetidos a análise pelo teste t de Student para dados vinculados, o qual identificou diferença estatisticamente significante em nível de 5% na quantificação de material obturador remanescente quando da comparação dos volumes obtidos com a análise do software Leica Qwin e aplicação da fórmula do volume do cone 11 truncado aos volumes obtidos pelas aferições tomográficas, sendo que a análise dos cortes pelo software Leica Qwin permitiu maior quantificação de material, mostrandose método adequado para análise. Em relação ao método tomográfico não houve diferença estatística significante entre a avaliação do remanescente de material obturador nos cortes ou nos espécimes íntegros. / The aim of the present study was to evaluate the effectiveness of computed tomography and cross section in quantifying the remaining filling material during retreatment. For that, 32 teeth were prepared, filled and after the period necessary to the sealer set, the specimens had their filling material removed and were reprepared. The amount of filling material were evaluate for different methods: computed tomography and Leica Qwin software. First, the volumes of filling material remaining were measured through the computed tomography with the specimens still entire. After, they were cross sectioned with a thickness of 1mm allowing measure of: the volume through computed tomography and the areas of remaining material in which section through the Leica Qwin software. To allow a comparative analysis among methods, the area values were used to calculate the filling material remaining volume using the truncated cone formula. The results were submitted to the t Student test for linked data which identify a significant difference to the level of 5% in the quantification of remaining material when the comparison of the volumes obtained after Leica Qwin analysis and application of truncated cone formula in relation to the results obtained from computed tomography, being the first method that allow the bigger quantification, therefore, most efficient. In relation the tomographic method there was no significant difference between the measured made in the intact specimen or after they were cross-sectioned.

Pacientes com linfoma de Hodgkin (LH) tratados com poliquimioterpia com adriamicina, bleomicina, vincristina e doxorrubicina (ABVD) apresentam resposta terapêutica distinta. Para aprimorar a avaliação prognóstica e a abordagem terapêutica em LH objetivamos avaliar o valor prognóstico da PET-FDG após 2 ciclos de ABVD (PET2) em pacientes com LH. Foram incluídos nesse estudo prospectivo 115 pacientes com diagnóstico recente de LH no período de agosto de 2005 a dezembro de 2007. Os pacientes foram estadiados com exame clínico, laboratorial, tomografia computadorizada e PET-FDG (PET0). Todos os pacientes foram tratados com ABVD e aqueles com massa tumoral extensa foram tratados com radioterapia associada. Após dois ciclos de ABVD os pacientes foram submetidos a PET2. Nenhum tratamento foi alterado baseado na PET2. Foi avaliado o valor prognóstico dos fatores clínicos, Índice Prognóstico Internacional (IPI) e PET2 em relação à sobrevida livre de eventos (SLE) em três anos. Dos 104 pacientes que foram avaliados, 82 atingiram remissão completa e 22 pacientes apresentaram falha de tratamento durante a mediana de 36 meses de acompanhamento. A SG e SLE em três anos foi de 94,2% e 74,2% respectivamente. A SLE em três anos da PET2 positiva foi de 54,3%, enquanto da PET2 negativa foi de 90,5% (p< 0.001). Na análise de subgrupos de pacientes com estádio precoce, avançado, IPI baixo e alto risco, a PET2 também apresentou correlação estatisticamente significativa com o prognóstico. Concluímos que a PET2 é o melhor fator prognóstico independente na avaliação de pacientes com LH / Patients with Hodgkin lymphoma (HL) treated with poliquimioteraphy with adriamycin, bleomycin, vincristine and doxorubicin (ABVD) have distinct therapeutic response. In order to improve the prognostic assessment and therapeutic approach in HL we have evaluated the prognostic value of FDG-PET after 2 cycles of ABVD (PET2). Were included in this prospective study 115 patients with newly diagnosed LH in the period of August 2005 to December 2007. The patients were staged with physical examination, laboratory, CT and PET-FDG (PET0). All patients were treated with ABVD and those with extensive tumor were treated with radiotherapy associated. After two cycles of ABVD patients underwent PET2. No treatment was changed based on PET2. We assessed the prognostic value of clinical factors, international prognostic score (IPS) and PET2 in relation to event-free survival (EFS) in three years. Of the 104 patients who finalized the evaluation, 82 achieved complete remission and 22 patients experienced treatment failure during the median of 36 months of follow-up. The EFS at three years was 74.2%. EFS in three years of PET2 positive was 54.3%, while the PET2 negative was 90.5% (p <0.001). In subgroup analysis of patients with early stage, advanced, low and high risk IPS, PET2 also showed significant correlation with the prognosis. We conclude that the PET2 is the best independent prognostic factor in the evaluation of overall patients with LH, or in subgroups of early, advance; low and high risk of HL

INTRODUCTION: Utilization of rapid maxillary expansion (RME) is common for the correction of sagittal discrepancies in orthodontic treatment. RME appliances will transmit a compressive force to the periodontal support structures. This resultant force can lead to resorption of the dento-alveolar structures leading to unwanted dental movements. The purpose of this retrospective study was to compare changes from a periodontal and root resorption perspective by means of computer tomography with tooth-borne and bonded expanders. METHODS: The sample comprised of cone beam computed tomography and spiral CT images of 41 subjects, 12 to 17 years old, with unilateral or bilateral posterior crossbites. 20 subjects treated previously with a bonded expander and 21 with a banded expander. Pre and post-treatment images were digitized and landmarks were identified to measure buccal and lingual cortex thickness, alveolar height, root length and angulation by means of a computerized method. RESULTS: RME with banded and bonded expanders have similar effects from periodontal and root resorption perspectives. Changes include increasing thickness of lingual alveolar bone 0.2 to 0.7 mm, decreases in buccal bone width 0.1 to 0.5 mm; and decreases in alveolar height 0.1 to 0.9 mm and root length 0.3 to 1.0mm of each support teeth. CONCLUSIONS: RME with banded and bonded expanders exhibited similar changes post-expansion and these variables should not play a role in selection of the type of device.

A angiografia coronariana por tomografia computadorizada (ACTC) é um exame bem estabelecido no diagnóstico da doença arterial coronariana. Entretanto, segmentos coronarianos submetidos a implante de stent podem apresentar limitação na avaliação luminal. O objetivo deste estudo é avaliar o valor adicional da perfusão miocárdica por tomografia computadorizada (PMTC) à avaliação anatômica isolada pela ACTC em portadores de stent, tendo o cateterismo (CATE) como referência. Quarenta e seis pacientes (56,9±7,2 anos, 28 homens) com indicação clínica de CATE em até 60 dias foram submetidos à avaliação combinada de ACTC e PMTC, por meio de tomógrafo de 64 detectores (Aquillion 64, Toshiba). A aquisição foi iniciada com a fase de estresse (PMTC) usando-se dipiridamol a 0,56mg/kg/4min e 60ml de contraste a 3ml/s, seguido de reversão com aminofilina 240mg e metoprolol (até 20mg). Em seguida, realizou-se a ACTC com 80-90ml de constraste a 5ml/s. Os dados da PMTC, da ACTC, e do CATE foram analisados por dois observadores independentes, sem informações clínicas dos pacientes. Primariamente analisou-se a ACTC, seguida da avaliação da PMTC. Concluída esta fase, os observadores tinham a possibilidade de reclassificar os segmentos coronarianos submetidos a stent cuja avaliação estivesse limitada ou inadequada por artefatos. A dose total média de radiação foi 15,83±4,93 mSv e todos os exames foram adequados. Um total de 129 segmentos coronarianos foi avaliado na ACTC, bem como os respectivos territórios miocárdicos pela PMTC. Destes, 54 territórios (42%) eram relacionados à presença de stents, sendo 19 com stents de avaliação adequada e 23 com avaliação luminal limitada, porém possível, e 12 segmentos de avaliação inadequada (sem possibilidade de avaliação luminal). Os valores de sensibilidade, especificidade, valor preditivo positivo, valor preditivo negativo e acurácia para a ACTC isolada nos territórios com stents foram de, respectivamente: 85%, 76%, 85%, 76% e 81%, e com o uso combinado da ACTC + PMTC foram de, respectivamente 88%, 95%, 97%, 83% e 92% (p=0,0314). Nos territórios com stent e avaliação luminal prejudicada (limitada ou inadequada) os valores para análise da ACTC isolada foram de, respectivamente: 83%, 71%, 75%, 80% e 77% e após a análise da ACTC + PMTC foram de, respectivamente: 89%, 94%, 94%, 89% e 92% (p = 0,0441). A avaliação combinada da ACTC + PMTC permitiu melhorar a acurácia diagnóstica da avaliação de obstrução coronariana significativa em pacientes portadores de stents, comparativamente à avaliação isolada da ACTC / Coronary computed tomography angiography (coronary CTA) is a well established examination in the diagnosis of coronary artery disease (CAD). However, the segments with prior coronary stent implantation may have limited luminal evaluation. The aim of this study is to assess the incremental value of myocardial computed tomography perfusion (myocardial CTP) to the anatomical assessment by coronary CTA alone in patients with stents, using catheterization (CAT) as a reference method. Forty-six patients (56.9 ± 7.2 years, 28 men) referred to CAT by clinical indication within 60 days, were evaluated with combined evaluation of coronary CTA and myocardial CTP through 64-detector CT scanner (Aquillion 64, Toshiba). The acquisition protocol began with the stress phase (myocardial CTP), using dipyridamole to 0.56 mg/kg/4min and 60ml of contrast (3ml/s), followed by a bolus of aminophylline 240 mg and metoprolol (up to 20mg). After, it was performed the coronary CTA wih 80-90ml of contrast (5 ml/s). Data from the myocardial CTP, coronary CTA and CAT were analyzed by two independent observers, with no knowledge to clinical information. The observers reviewed the coronary CTA findings, and in a second time performed the evaluation of myocardial CTP. So, they had the possibility to reclassify segments with coronary stent that were considered with limited or inadequate assessment due to artifacts. Mean total dose of radiation was 15.83 ± 4.93 mSv, and all examinations were interpretable. A total of 129 coronary segments were evaluated by coronary CTA, and also were their correspondent myocardial territories by myocardial CTP. Of these, 54 territories (42%) were related to the presence of stents, 19 stents with adequate evaluation, 23 with limited evaluation, but possible, and 12 with inadequate evaluation (no luminal assessment possible). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for the coronary CTA in territories with stents were respectively: 85%, 76%, 85%, 76% and 81%, and the combined use of coronary CTA + Myocardial CTP were respectively 88%, 95%, 97%, 83% and 92% (p=0.0314). In territories with impaired luminal stent evaluation (limited or inadequate), the values for analysis of coronary CTA alone were: 83%, 71%, 75%, 80% and 77%, and after analysis of myocardial CTP were, respectively: 89%, 94%, 94%, 89% and 92% (p = 0.0441). The combined evaluation of the coronary CTA and myocardial CTP has improved the diagnostic accuracy of the evaluation of significant coronary obstruction in patients with stents, compared to the assessment of coronary CTA alone

Por meio do exame tridimensional de Tomografia computadorizada de feixe cônico (TCFC) é possível avaliar a área de interesse previamente aos procedimentos com maior precisão. As variações anatômicas são estruturas que devem ser consideradas para a realização de cirurgias, como a foramina acessória da região anterior da maxila (FARAM). O objetivo principal do presente estudo foi avaliar a FARAM, em 150 exames de TCFC, obtidas no aparelho ICat Classic®. Por meio do programa ICat Vision® foram mensuradas o diâmetro, a distância da FARAM ao forame incisivo (FARAM-FI), da FARAM ao rebordo alveolar vestibular (FARAM-RAV) e da FARAM a sutura intermaxilar (FARAM-SI). Também foi avaliada a trajetória dos canais ósseos formados a partir da FARAM. Nos pacientes dentados, foram localizados por meio da área dos dentes: incisivo central, incisivo lateral e caninos. Foi realizada a correlação entre a presença da FARAM e o gênero e a idade. Dos 150 exames, a FARAM estava presente em 21 exames (14%). Destes, dez pacientes eram edêntulos na região de interesse de estudo e não foi possível localizar a foramina em relação aos dentes. Nenhum exame apresentou a FARAM relacionada ao incisivo central, em sete estavam relacionadas ao incisivo lateral e em quatro estavam relacionadas ao canino. Nenhum exame apresentou a FARAM bilateralmente, sendo que treze foram localizadas no lado direito e oito do lado esquerdo. O diâmetro médio da FARAM foi de 1,57 ± 0,38 mm. As médias das distâncias de FARAM-RAV foi de 11,65 ± 3,34 mm, FARAM-FI foi de 8,86 ± 2,72 mm e FARAM-SI, foi de 6,37 ± 2,9 mm. A trajetória do canal ósseo mais comum foi ascendente/oblíqua em direção a região anterior do assoalho da cavidade nasal. A correlação entre a presença da FARAM e o gênero foi estaticamente significante para os homens (p=0,055) no teste do qui-quadrado. No entanto, não foi estatisticamente significante para a idade. / Through cone beam computed tomography (CBCT) is possible to evaluate the region of interest before surgical procedures in tridimensional view. Anatomical variations should be considered for performing surgeries, as the additional foraminas in anterior maxilla (AFAM). The main aim of the present study is evaluate AFAM in 150 CBCT exams, obtained through ICat Classic® device. In ICat Vision® software, the diameter, the distance from the AFAM to the incisive foramen (AFAM-IF), AFAM to the vestibular alveolar ridge (AFAM-VAR) and AFAM intermaxillary suture (AFAM-IS) were measured. It was also evaluated the trajectory of the bony canals related to AFAM. In dentate patients, AFAM was located through the teeth area: central incisor, lateral incisor and canines. The correlation between the presence of FARAM and gender and age was investigated. The AFAM was presented in 21 exams (14%). In the positive exams, 10 patients were edentulous in the region of study interest and it was not possible to locate the foramen in relation to the teeth. Any exam presented the AFAM related to the central incisor, in seven were related to the lateral incisor and in four were related to the canine. Any exam presented the AFAM bilaterally, of which thirteen were located on the right side and eight on the left side. The mean diameter of the AFAM was 1.57 ± 0.38 mm. The distance of the AFAM-VAR 11.65 ± 3.34 mm, AFAMIF was 8.86 ± 2.72 mm and AFAM-IS was 6.37 ± 2.9 mm. The most common bone canal trajectory was upward/ oblique to the anterior region of the floor of the nasal cavity. The correlation between the presence of AFAM and the gender was statically significant for males (p=0.055) in the chi-square test. However, it was not statistically significant for age.

As radiografias intraorais ilustram bem os estágios de reabsorção periodontal nas regiões interproximais. Entretanto, a sobreposição de estruturas dificulta avaliação da perda óssea nas corticais vestibular e lingual. A tomografia computadorizada por feixe cônico (TCFC) é de elevada importância em várias especialidades odontológicas, tais como implantodontia, avaliação de lesões ósseas, estudo da articulação têmporo-mandibular e cirurgia buco-maxilo-facial. A TCFC também tem tido crescente indicação em outras áreas, como a periodontia e endodontia. O objetivo no presente estudo foi a) estabelecer o protocolo de aquisição mais adequado para a detecção de lesões incipientes de furca simuladas quimicamente; e b) avaliar a reprodutibilidade, sensibilidade e especificidade da TCFC, para a finalidade previamente citada. No presente estudo, foram utilizadas 15 mandíbulas suínas maceradas, que apresentavam o segundo molar íntegro e as corticais adjacentes preservadas As simulações de lesões em região de furca foram feitas com aplicação de ácido perclórico a 70%, em até quatro sítios possíveis em cada mandíbula (vestibular do lado direito, lingual do lado direito, vestibular do lado esquerdo, lingual do lado esquerdo) por um examinador participante que não avaliou as imagens. Nos 60 sitios possíveis, foram escolhidos aleatoriamente 20 para as simulações das lesões. Posteriormente, as mandíbulas foram submetidas à TCFC (i-CAT Next Generation) em dois. protocolos de aquição: voxel 0,2 mm e 0,25 mm, ambos com FOV de 6 cm de altura por 16 cm de diâmetro e com 26,9 segundos de tempo. Dois observadores (radiologistas previamente calibrados) avaliaram os exames duas vezes, em ordem aleatória, sob iluminação controlada. Os observadores foram orientados a direcionar a avaliação das regiões dos segundos molares, e questionados se havia lesão ou não nos sítios avaliados. A interpretação das imagens foi realizada em uma estação de trabalho independente localizada no Laboratório de Imagem em Terceira Dimensão da Faculdade de Odontologia da Universidade de São Paulo, utilizando o software Xoran (Xoran Technologies). A sensibilidade, especificidade e reprodutibilidade da TCFC foram avaliadas nos dois protocolos. A TCFC apresentou especificidade alta, sensibilidade baixa e reprodutibilidade moderada na detecção de lesões incipientes de furca. A influência do tamanho do voxel não foi estatisticamente significativa na detecção destas lesões. / Intraoral radiographs illustrate the stages of resorption in periodontal interproximal regions. However, overlapping structures hinders evaluation of bone loss in the buccal and lingual cortical plates. The cone beam computed tomography (CBCT) is of high importance in various dental specialties such as implantology, evaluation of bone lesions, the study of temporomandibular joint and maxillo-facial surgery. The CBCT has also been increasing indications in other areas, such as periodontics and endodontics. The aim of this study was to establish a) the acquisition protocol most suitable for the detection of incipient furcation invasion chemically simulated and b) assess the reproducibility, sensitivity and specificity of CBCT for the purpose previously mentioned. In this study, 15 pigs macerated mandibles were used, which showed the second molar and the adjacent cortical integrity preserved. Simulated lesions in the furcation area were made with application of 70% perchloric acid, up to four possible sites in each jaw (the right buccal, the right lingual, the left buccal, and left lingual side) by an examiner participant who did not evaluate the images. In the 60 possible sites, 20 were randomly chosen for the simulated lesions. Subsequently, the mandibles underwent cone beam computed tomography (Next Generation i-CAT) in two acquisition protocols: at 0.2 mm and 0.25 mm voxel, both with FOV of 6 cm height by 16 cm in diameter and 26.9 seconds of time. Two observers (calibrated radiologists) evaluated the examinations twice, in random order under controlled lighting. Observers were instructed to direct the evaluation to the regions of the second molars, and they were asked if there were or not injuries on those avaluated sites. Image interpretation was performed on an independent workstation located at the Third Dimension Laboratory of Image in the School of Dentistry, University of São Paulo, using the software Xoran (Xoran Technologies). The sensitivity, specificity and reproducibility of CBCT were assessed in both trials. The CBCT showed high specificity, low sensitivity and moderate reproducibility in the detection of incipient lesions, furcation. The influence of voxel size was not statistically significant in detecting these lesions.

Over 190,000 Americans die every year from lung cancer, making it the number one cause of death from cancer in America. Lung cancer has maintained the same low five year survival rate, of 13-15%, over the last thirty years. There is therefore desperate need for improvement in diagnostic and therapeutic techniques for lung cancer. Multidetector computed tomography (MDCT) is being increasingly used for lung cancer detection and characterization. While national lung cancer screening trials have shown MDCT to be effective in detecting even very small lung nodules, the characterization achievable through this modality is poor. The majority of non-small cell lung cancer tumors are histologically heterogeneous and consist of malignant tumor cells, necrotic tumor cells, fibroblastic stromal tissue, and inflammation, however the extent of this heterogeneity is unknown. Geometric and tissue density heterogeneity are under utilized in MDCT representations of lung tumors for distinguishing between malignant and benign nodules because there has been no thorough investigation into the correlation between radiographic heterogeneity and corresponding histological content in 3D. To understand and to make more effective this lung cancer characterization by MDCT, two vital steps must be taken. Firstly, an understanding of the 3D structure and content of tissue types that constitute a lung nodule must be established. Secondly, this knowledge must then be used to assess how nodule tissue content corresponds to the heterogeneity apparent in MDCT data, impacting diagnosis, planning biopsy procedures and nodule change analysis. In this study we have developed a process model for establishing a direct correlation between histopathology and non-destructive radiological imaging. We provide the 3D structural and pathological detail of lung cancer nodules and surrounding tissues using a purpose built Large Image Microscope Array (LIMA). This information served as the basis for registration of MDCT images of the human nodule before and after resection, computed micro-tomography (micro-CT) detail and histopathology.

Medical imaging is a powerful tool for clinical practice allowing in-vivo insight into a patient’s disease state. Many modalities exist, allowing for the collection of diverse information about the underlying tissue structure and/or function. Traditionally, medical professionals use visual assessment of scans to search for disease, assess relevant disease predictors and propose clinical intervention steps. However, the imaging data contain potentially useful information beyond visual assessment by trained professional. To better use the full depth of information contained in the image sets, quantitative imaging characteristics (QICs), can be extracted using mathematical and statistical operations on regions or volumes of interests. The process of using QICs is a pipeline typically involving image acquisition, segmentation, feature extraction, set qualification and analysis of informatics. These descriptors can be integrated into classification methods focused on differentiating between disease states. Lung cancer, a leading cause of death worldwide, is a clear application for advanced in-vivo imaging based classification methods. We hypothesize that QICs extracted from spatially-linked and size-standardized regions of surrounding lung tissue can improve risk assessment quality over features extracted from only the lung tumor, or nodule, regions. We require a robust and flexible pipeline for the extraction and selection of disease QICs in computed tomography (CT). This includes creating an optimized method for feature extraction, reduction, selection, and predictive analysis which could be applied to a multitude of disease imaging problems. This thesis expanded a developmental pipeline for machine learning using a large multicenter controlled CT dataset of lung nodules to extract CT QICs from the nodule, surrounding parenchyma, and greater lung volume and explore CT feature interconnectivity. Furthermore, it created a validated pipeline that is more computationally and time efficient and with stability of performance. The modularity of the optimized pipeline facilitates broader application of the tool for applications beyond CT identified pulmonary nodules. We have developed a flexible and robust pipeline for the extraction and selection of Quantitative Imaging Characteristics for Risk Assessment from the Tumor and its Environment (QIC-RATE). The results presented in this thesis support our hypothesis, showing that classification of lung and breast tumors is improved through inclusion of peritumoral signal. Optimal performance in the lung application achieved with the QIC-RATE tool incorporating 75% of the nodule diameter equivalent in perinodular parenchyma with a development performance of 100% accuracy. The stability of performance was reflected in the maintained high accuracy (98%) in the independent validation dataset of 100 CT from a separate institution. In the breast QIC-RATE application, optimal performance was achieved using 25% of the tumor diameter in breast tissue with 90% accuracy in development, 82% in validation. We address the need for more complex assessments of medically imaged tumors through the QIC-RATE pipeline; a modular, scalable, transferrable pipeline for extracting, reducing and selecting, and training a classification tool based on QICs. Altogether, this research has resulted in a risk assessment methodology that is validated, stable, high performing, adaptable, and transparent.