Método de detección de distorsiones de la arquitectura de la glándula mamaria a partir de imágenes radiológicas

Este documento de tesis presenta la planeación, implementación y pruebas de un nuevo método que sirve como soporte para la detección de distorsiones de la arquitectura en la glándula mamaria a partir de imágenes de radiología de mama. El método asiste a los especialistas en el proceso de decisión diagnóstica como segundo intérprete en el análisis de mamografías, mediante la integración de cuatro etapas principales: preprocesamiento, detección de regiones de interés que sean candidatas a la posible presencia de distorsión de la arquitectura de la glándula mamaria, extracción y selección de características de las regiones de interés detectadas y finalmente clasificación de esas regiones de interés con base en las características extraídas de las mismas. El método propuesto se valida mediante el análisis de imágenes mamográficas de la base de datos DDSM, logrando valores de precisión general hasta de un 90.7% lo cual lo convierte en una base importante en la búsqueda de la reducción del alto número de diagnósticos errados que conducen a las altas tasas de morbilidad por cáncer de mama que se presentan en el mundo./Abstract. This thesis presents the design, implementation and test of a new method that serves as support for the detection of architectural distortion in the mammary gland from breast radiology images. The method proposed here assists the specialists in the diagnosis of breast cáncer through four main phases: preprocessing, detection of regions of interest that are candidates for the possible presence of architectural distortion of the mammary gland, feature selection and extraction and finally classification of these regions of interest based on the extracted features. The method proposed in this thesis is validated through the analysis of mammographic images from DDSM obtaining values of 90.7% in the overall accuracy. This result is a very important contribution and encourage the research in order to reduce the high number of misdiagnoses that are currently presented and lead to high rates of morbidity from breast cáncer.Maestrí

Semi-automated search for abnormalities in mammographic X-ray images

Breast cancer is the most commonly diagnosed cancer among Canadian women; x-ray mammography is the leading screening technique for early detection. This work introduces a semi-automated technique for analyzing mammographic x-ray images to measure their degree of suspiciousness for containing abnormalities. The designed system applies the discrete wavelet transform to parse the images and extracts statistical features that characterize an image’s content, such as the mean intensity and the skewness of the intensity. A naïve Bayesian classifier uses these features to classify the images, achieving sensitivities as high as 99.5% for a data set containing 1714 images. To generate confidence levels, multiple classifiers are combined in three possible ways: a sequential series of classifiers, a vote-taking scheme of classifiers, and a network of classifiers tuned to detect particular types of abnormalities. The third method offers sensitivities of 99.85% or higher with specificities above 60%, making it an ideal candidate for pre-screening images. Two confidence level measures are developed: first, a real confidence level measures the true probability that an image was suspicious; and second, a normalized confidence level assumes that normal and suspicious images were equally likely to occur. The second confidence measure allows for more flexibility and could be combined with other factors, such as patient age and family history, to give a better true confidence level than assuming a uniform incidence rate. The system achieves sensitivities exceeding those in other current approaches while maintaining reasonable specificity, especially for the sequential series of classifiers and for the network of tuned classifiers