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Background- Mediastinal staging is the rate-limiting step prior to initiation of lung cancer treatment and is essential in identifying the most appropriate treatment for the patient. However, this process is often complex and involves multiple imaging modalities including invasive and non-invasive methods for the assessment of lymph nodes in the mediastinum which are error prone. The use of Artificial Intelligence may be able to provide more accurate and precise measurements and eliminate error associated with medical imaging. Methods-This thesis was conducted in three parts. In Part 1, we synthesized and critically appraised the methodological quality of existing studies that use Artificial Intelligence to diagnosis and stage lung cancer from thoracic imaging based on lymph node features. In Part 2, we determined the inter-rater reliability of segmentation of the ultrasonographic lymph node features performed by an experienced endoscopist (manually) compared to NeuralSeg (automatically). In Part 3, we developed and validated a deep neural network through a clinical prediction model to determine if NeuralSeg could learn and identify ultrasonographic lymph node features from endobronchial ultrasound images in patients undergoing lung cancer staging. Results- In Part 1, there were few studies in the Artificial Intelligence literature that provided a complete and detailed description of the design, Artificial Intelligence architecture, validation strategies and performance measures. In Part 2, NeuralSeg and the experienced endosonographer possessed excellent inter-rater correlation (Intraclass Correlation Coefficient = 0.76, 95% CI= 0.70 – 0.80, p<0.0001). In Part 3, NeuralSeg’s algorithm had an accuracy of 73.78% (95% CI: 68.40% to 78.68%), a sensitivity of 18.37% (95% CI: 8.76% to 32.02%) and specificity of 84.34% (95% CI: 79.22% to 88.62%). Conclusions- Analysis of staging modalities for lung cancer using Artificial Intelligence may be useful for when results are inconclusive or uninterpretable by a human reader. NeuralSeg’s high specificity may inform decision-making regarding biopsy if results are benign. Prospective external validation of algorithms and direct comparisons through cut-off thresholds are required to determine their true predictive capability. Future work with a larger dataset will be required to improve and refine the algorithm prior to trials in clinical practice. / Thesis / Master of Science (MSc) / Before deciding on treatment for patients with lung cancer, a critical step in the investigation is finding out whether the lymph nodes in the chest contain cancer cells. This is accomplished through medical imaging of the lymph nodes or taking a biopsy of the lymph node tissue using a needle attached to a scope that is entered through the airway wall. The purpose of these tests is to ensure that lung cancer patients receive the optimal treatment option. However, imaging of the lymph nodes is heavily reliant on human interpretation, which can be error prone. We aimed to critically analyze and investigate the use of Artificial Intelligence to enhance clinician performance for image interpretation. We performed a search of the medical literature for the use of Artificial Intelligence to diagnosis lung cancer from medical imaging. We also taught a computer program, known as NeuralSeg, to learn and identify cancerous lymph nodes from ultrasound imaging. This thesis provides a significant contribution to the Artificial Intelligence literature and provides recommendations for future research.

The task of comprehending charts [1, 2, 3] presents significant challenges for machine learning models due to the diverse and intricate shapes of charts. The chart extraction task ensures the precise identification of key components, while the chart question answering (ChartQA) task integrates visual and textual information, facilitating accurate responses to queries based on the chart's content. To approach ChartQA, this research focuses on two main aspects. Firstly, we introduce ChartFormer, an integrated framework that simultaneously identifies and classifies every chart element. ChartFormer extends beyond traditional data visualization by identifying descriptive components such as the chart title, legend, and axes, providing a comprehensive understanding of the chart's content. ChartFormer is particularly effective for complex instance segmentation tasks that involve a wide variety of class objects with unique visual structures. It utilizes an end-to-end transformer architecture, which enhances its ability to handle the intricacies of diverse and distinct object features. Secondly, we present Question-guided Deformable Co-Attention (QDCAt), which facilitates multimodal fusion by incorporating question information into a deformable offset network and enhancing visual representation from ChartFormer through a deformable co-attention block. / Master of Science / Real-world data often encompasses multimodal information, blending textual descriptions with visual representations. Charts, in particular, pose a significant challenge for machine learning models due to their condensed and complex structure. Existing multimodal methods often neglect these graphics, failing to integrate them effectively. To address this gap, we introduce ChartFormer, a unified framework designed to enhance chart understanding through instance segmentation, and a novel Question-guided Deformable Co-Attention (QDCAt) mechanism. This approach seamlessly integrates visual and textual features for chart question answering (ChartQA), allowing for more comprehensive reasoning. ChartFormer excels at identifying and classifying chart components such as bars, lines, pies, titles, legends, and axes. The QDCAt mechanism further enhances multimodal fusion by aligning textual information with visual cues, thereby improving answer accuracy. By dynamically adjusting attention based on the question context, QDCAt ensures that the model focuses on the most relevant parts of the chart. Extensive experiments demonstrate that ChartFormer and QDChart significantly outperform their baseline models in chart component recognition and ChartQA tasks by 3.2% in mAP and 15.4% in accuracy, respectively, providing a robust solution for detailed visual data interpretation across various applications. These results highlight the efficacy of our approach in providing a robust solution for detailed visual data interpretation, making it applicable to a wide range of domains, from scientific research to financial analysis and beyond.

Despite facing technical issues (e.g., overfitting, vanishing and exploding gradients), deep neural networks have the potential to capture complex patterns in data. Understanding how depth impacts neural networks performance is vital to the advancement of novel deep learning architectures. By varying hyperparameters on two sets of architectures with different depths, this thesis aims to examine if there are any potential benefits from developing deep networks for segmenting intracranial aneurysms from 3D TOF-MRA scans in the ADAM dataset. / Master of Science / With the technologies we have today, people are constantly generating data. In this pool of information, gaining insight into the data proves to be extremely valuable. Deep learning is one method that allows for automatic pattern recognition by iteratively improving the disparity between its prediction and the ground truth. Complex models can learn complex patterns, and such models introduce challenges. This thesis explores the potential benefits of deep neural networks whether they stand to gain improvement despite the challenges. The models will be trained to segment intracranial aneurysms from volumetric images.

Dans ce mémoire nous présentons une méthode pour référencer deux nuages de points denses. Cette méthode commence par l'analyse d'un nuage de points de grand volume, composé d’environ 2 millions de points recueillis par un LiDAR (Light Detection And Ranging) monté sur une voiture, afin de le segmenter en surfaces représentatives pertinentes en termes de géométrie et de localisation. Ensuite, nous présentons la construction de descripteurs pour chacun des segments trouvés afin d’obtenir des caractéristiques significatives des segments. Ces descripteurs sont le FPFH (Fast Point Feature Histograms) et l’histogramme des orientations de surface. Pour finir, les descripteurs recueillis sur deux nuages de points différents du même environnement extérieur sont comparés pour repérer les segments similaires et ainsi permettre la localisation du véhicule par rapport à l'environnement extérieur. / In this work we present a method to reference two dense point clouds. We begin by analyzing a point cloud of a large number of points, approximately 2 million points collected by a LiDAR mounted on a car, in order to segment this point cloud into surfaces that feature representative regions of the point cloud that are interesting in terms of geometry. Then the construction of descriptors for each segment found is made to identify significant features. These descriptors are the FPFH (Fast Point Feature Histograms) and the surface orientation histogram. Finally, the descriptors collected on two different point clouds of the same outdoor environment are compared to identify similar segments and thus to allow the location of the vehicle in relation to the outdoor environment.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.