What are three limitations of breast ultrasound?

1. The superficial location of the breast allows the use of a high frequency transducer, but the ability to penetrate the breast is diminished. Therefore, it may be necessary to use a lower-frequency transducer (e.g., 5 MHz) to penetrate large breasts.
2. The appearance of benign and malignant solid tissues can be similar.
3. Breast ultrasound is unable to image microcalcifications.