A New Computer-Aided Diagnosis System with Modified Genetic Feature Selection for BI-RADS Classification of Breast Masses in Mammograms

Mammography remains the most prevalent imaging tool for early breast cancer screening. The language used to describe abnormalities in mammographic reports is based on the breast Imaging Reporting and Data System (BI-RADS). Assigning a correct BI-RADS category to each examined mammogram is a strenuous and challenging task for even experts. This paper proposes a new and effective computer-aided diagnosis (CAD) system to classify mammographic masses into four assessment categories in BI-RADS. The mass regions are first enhanced by means of histogram equalization and then semiautomatically segmented based on the region growing technique. A total of 130 handcrafted BI-RADS features are then extrcated from the shape, margin, and density of each mass, together with the mass size and the patient's age, as mentioned in BI-RADS mammography. Then, a modified feature selection method based on the genetic algorithm (GA) is proposed to select the most clinically significant BI-RADS features. Finally, a back-propagation neural network (BPN) is employed for classification, and its accuracy is used as the fitness in GA. A set of 500 mammogram images from the digital database of screening mammography (DDSM) is used for evaluation. Our system achieves classification accuracy, positive predictive value, negative predictive value, and Matthews correlation coefficient of 84.5%, 84.4%, 94.8%, and 79.3%, respectively. To our best knowledge, this is the best current result for BI-RADS classification of breast masses in mammography, which makes the proposed system promising to support radiologists for deciding proper patient management based on the automatically assigned BI-RADS categories

Wavelet-Based Automatic Breast Segmentation for Mammograms

As part of a first of its kind analysis of longitudinal mammograms, there are thousands of mammograms that need to be analyzed computationally. As a pre- processing step, each mammogram needs to be converted into a binary (black or white) spatial representation in order to delineate breast tissue from the pectoral muscle and image background, which is called a mammographic mask. The current methodology for completing this task is for a lab member to manually trace the outline of the breast, which takes approximately three minutes per mammogram. Thus, reducing the time cost and human subjectivity when completing this task for all mammograms in a large dataset is extremely valuable. In this thesis, an automated breast segmentation algorithm was adapted from a multi-scale gradient-based edge detection approach called the 2D Wavelet Transform Modulus Maxima (WTMM) segmentation method. This automated masking algorithm incorporates the first-derivative Gaussian Wavelet Transform to identify potential edge detection contour lines called maxima chains. The candidate chains are then transformed into a binary mask, which is then compared with the original manual delineation through the use of the Sorenson-Dice Coefficient (DSC). The analysis of 556 grayscale mammograms with this developed methodology produced a median DSC of 0.988 and 0.973 for craniocaudal (CC) and mediolateral oblique (MLO) grayscale mammograms respectively. Based on these median DSCs, in which a perfect overlap score is 1, it can be concluded a wavelet-based automatic breast segmentation algorithm is able to quickly segment the pectoral muscle and produce accurate binary spatial representations of breast tissue in grayscale mammograms

A New Approach to the Detection of Mammogram Boundary

Mammography is a method used for the detection of breast cancer. computer-aided diagnostic (CAD) systems help the radiologist in the detection and interpretation of mass in breast mammography. One of the important information of a mass is its contour and its form because it provides valuable information about the abnormality of a mass. The accuracy in the recognition of the shape of a mass is related to the accuracy of the detected mass contours. In this work we propose a new approach for detecting the boundaries of lesion in mammography images based on region growing algorithm without using the threshold, the proposed method requires an initial rectangle surrounding the lesion selected manually by the radiologist (Region Of Interest), where the region growing algorithm applies on lines segments that attach each pixel of this rectangle with the seed point, such as the ends (seeds) of each line segment grow in a direction towards one another. The proposed approach is evaluated on a set of data with 20 masses of the MIAS base whose contours are annotated manually by expert radiologists. The performance of the method is evaluated in terms of specificity, sensitivity, accuracy and overlap. All the findings and details of approach are presented in detail