Screening mammography is used for the early detection of breast cancer in asymptomatic women (between the ages of 50 and 69 in Canada). Screen Test: Alberta Program for the Early Detection of Breast Cancer has been in operation since 1990, and attracts the participation of over 21,000 women per year. Screen Test has offices in Calgary and Edmonton, and offers extended service with three mobile units to more than 100 sites in the province of Alberta. Mammograms are difficult images to interpret, especially in the screening context where the probability of encountering an abnormality is low and patient information is limited. A cost-effective, efficient method needs to be developed in order to achieve high diagnostic accuracy.
Diagnostic mammography refers to the radiological examination of symptomatic women who exhibit clinical signs such as a palpable lump, skin puckering, or nipple retraction, or as a result of screening. Mammography is used to detect abnormalities and classify them as benign or malignant. Ambiguous cases with suspicious features detected on mammograms are evaluated further with adjunctive imaging procedures. Depending on the characteristics of the abnormality, these procedures may include supplementary views, ultrasound, magnification mammography, magnetic resonance imaging, computed tomography, and nuclear medicine techniques. Biopsy is indicated if these methods do not lead to a definite diagnosis but indicate a high suspicion for malignancy, and confirmation of malignancy is required. Objective methods for the analysis of mammographic features are needed for the development of computer methods to assist radiologists in the evaluation of ambiguous features; that is, for computer-aided diagnosis (CAD) of breast cancer. Current research is directed toward the development of digital mammographic imaging and image analysis systems that can detect features, classify them, and give visual prompts to the radiologist, such as the Image Checker by R2 Technology, EasyVision RAD used with Philips' Computed Radiography system, and Second Look from iCAD.
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