The pectoralis muscle is imaged on which modalities?

• A. Ultrasound and mammography
• B. Ultrasound only
• C. Mammography only
• D. MRI

Answer: (A)

The pectoralis muscle can be seen with two common breast imaging methods. In mammography, the pectoralis major helps define the posterior edge of the breast and is visible on views that include the chest wall, especially the mediolateral oblique view, where it appears as a dense, posterior contour. In ultrasound, the muscle lies behind the breast tissue and presents as a thick, hypoechoic, layered structure with visible fibrous bands, making it easy to identify when imaging deep or near the chest wall. Because both ultrasound and mammography routinely image the pectoralis muscle, that combination best reflects how this structure is visualized in everyday practice. (MRI can also show chest wall muscles, but the question emphasizes the two standard breast imaging modalities.)