Mammographic screening of women age 40 and older can reduce breast cancer deaths by at least 30% to 40%. However, not all cancers are detected by mammography. Although a new supplementary modality for screening could, in theory, fill in this detection gap, such utilization must be based on rigorous demonstration of its ability to consistently and frequently find early cancers missed by mammography, such as those occurring in dense breasts or rapidly growing interval cancers that surface clinically between mammographic screens. After an abnormality is found at mammographic screening, supplementary mammographic views and/or ultrasound are now used to match the finding with an ACR BIRADS final diagnostic assessment category to indicate the relative likelihood of a normal, benign, or malignant diagnosis so that routine screening, short interval follow-up, or biopsy can then be advised. Appropriate categorization will maximize early cancer detection and minimize false-positive biopsies. Application of a new imaging method to this type of diagnostic evaluation requires well-designed studies to determine its effectiveness for this purpose.