The quantification of coronary artery calcium (CAC) score is a crucial metric for evaluating atherosclerotic plaque accumulation within coronary arteries, providing valuable predictive insights into coronary artery disease (CAD) events. Automated methods for CAC assessment using cardiac computed tomography (CT) have been extensively researched. However, a key aspect of these techniques is the accurate localization and segmentation of the heart within CT scans. This study presents a model-driven investigation into the efficacy of mediastinum segmentation, emphasizing its potential impact on CAC quantification in cardiac images. Utilizing a U-Resnet architecture, our methodology focuses on achieving a balance between model compactness and predictive capacity. The research involves two distinct datasets: one from a local medical institution and another serving as an external benchmark. The proposed model has demonstrated superior generalization in medical image segmentation exhibiting high accuracy in identifying true mask pixels within both its training and unseen datasets. Performance metrics showcase its success, with an average Dice Similarity Coefficient (DS) of 0.78, Precision (Pr) of 0.81, and Sensitivity (Se) of 0.81, surpassing the classical U-net model. Accurate localization and segmentation of the heart within CT images hold significant potential for facilitating the quantification of calcium deposits, contributing to the evaluation of coronary artery disease. Moreover, our research emphasizes the importance of recognizing potential labeling disparities in public datasets, attributing them to diverse labeling practices. In conclusion, this study highlights the model's potential in robust mediastinum segmentation, with direct implications for enhancing accuracy in CAC quantification within cardiac images. This contribution advances the field of accurate cardiac image analysis, ultimately benefiting patient care and enabling a more precise assessment of cardiovascular disease.
Cardiac motion quantification in magnetic resonance (MR) images provides vital information to diagnose and evaluate cardiovascular diseases. Motion quantification can be obtained from routinely acquired MR images. However, the methods available for motion estimation present many sources of inconsistencies, thus creating constraints to use it as a reliable diagnostic technique. Recently, convolutional neural networks (CNNs) have demonstrated to be a powerful tool for many different imaging tasks, including optical flow estimation, a technique widely used for motion estimation. In this work, we evaluate the suitability of a compact and powerful CNN architecture based on Pyramid, Warping, and Cost Volume (PWC) for motion estimation in synthetic cardiac resonance images. The synthetic images were generated using the extended cardiac-torso (XCAT) and MRXCAT software, which generates temporal series of highly detailed MR images and their corresponding ground-truth motion field, which would be impossible to obtain in real-life data. The CNN training was unsupervised, simulating real data. The ground-truth provided by the synthetic images was used to evaluate the PWC performance, determining its reliability. The CNN achieved an average end-point-error of 0.61 ± 0.25 pixel and a mean absolute error of 0.38 ± 0.15 pixel in the test set, surpassing state-of-the-art methods. The results obtained in this work indicate a high potential of the unsupervised PWC network for future applications in real cardiac images.
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