An MRI machine can take cross-sectional images through different parts of the body and may be a very sensitive tool for finding certain breast cancers. MRI might prove to be better than either mammography or ultrasound in determining the extent of the cancer and where it's located. And since breast implants can interfere with conventional mammography, MRI can also be helpful in examining women with silicone implants, Yaffe notes. Needle Biopsies A decade ago a surgical biopsy was the preferred way to examine breast tissue for an abnormality. Now many women can avoid this procedure.
Needle biopsies leave little or no scarring of the breast.
Two types of procedures are used, depending on the patient's situation. Fine-needle aspiration biopsy, or FNA, uses a needle no wider than a straight pin, requires no anesthesia and offers fast results, sometimes in less than 15 minutes. But a specially trained pathologist must be on hand to evaluate the cells removed, and since the technique harvests few cells, it may produce ambiguous results. The other procedure, core needle biopsy, requires a local anesthetic and is more invasive. The physician guides the needle to its target, sometimes using mammography or ultrasound.