In about 10% of screening mammograms, a question arises about a finding on the images. These images are interpreted as “Incomplete.” This means that more mammogram views and/or an ultrasound exam may need to be performed in order to finish the exam. Most of these follow-up studies are normal. However, sometimes a biopsy is necessary to further evaluate a finding. Fortunately, most breast biopsies can be accurately performed with a needle and do not require surgery. Depending on the finding, a needle biopsy is performed – using either stereotactic, ultrasound, or MRI guidance.


A mammogram may reveal an abnormal lump or lesion in the breast which cannot be felt. The American Cancer Society recommends that even when the mammogram is normal, a lump that can be felt should always be biopsied. A biopsy will clarify whether a lump is a benign or malignant (cancerous) lesion. A biopsy is the only method of determining whether a breast abnormality is cancer. This removal (tissue sampling) of the tissue can be done through surgery or by needle. The type of procedure used is determined by the appearance, feel (palpability) and location of the lump or abnormality. When the tissue is sampled, it is sent to a pathology lab for analysis.

Stereotactic-Guided Breast Biopsy – The Seattle Breast Center was one of the first facilities in the region to put this technology into practice over a decade ago. With the use of a specially designed table, two digital x-ray images are taken from different angles, allowing the radiologist to precisely localize the area to biopsied. Once the area has been located, the radiologist numbs the area with a local anesthetic, then uses computer guidance for precise needle placement and collection of small tissue samples.

Ultrasound-Guided Needle Biopsy – Ultrasound uses sound waves to produce a picture of the breast tissue. This picture helps identify lumps or other changes in the breast. The radiologist uses ultrasound to locate the area for biopsy and to direct the needle used in collecting breast tissue samples. If the lesion is a cyst, a cyst aspiration (removing the fluid from a cyst can also be performed using ultrasound guidance This procedure takes less than 20 minutes to perform.

MRI-guided needle biopsy – The Seattle Breast Center offers state-of-the-art breast MRI for the diagnosis and evaluation of breast cancer. If a lesion is found which is detectable only by MRI, we may perform a MRI-guided biopsy to sample the tissue.

These methods are as accurate as a surgical biopsy and are performed on an outpatient basis, taking approximately an hour to perform. Furthermore, the patient can resume normal, non-strenuous activities shortly after the procedure is done.

Magnetic Resonance Imaging (MRI)

Northwest Hospital performs high quality magnetic resonance imaging (MRI) of the breast. We use state-of-the-art equipment including a dedicated bilateral breast surface coil. Magnetic resonance imaging is a technique that is used to evaluate the integrity of breast implants and to better define the presence, or state, of breast cancer. Medical indications (reasons) for breast MRI are evolving, and are the subject of many studies around the country.
The patient lies on her stomach within the scanning field for approximately 25 minutes. Images are obtained without and with intravenous contrast material. If the examination is simply for implant evaluation, no contrast material may be needed. Our Seattle Breast Center radiologists, specifically trained in MRI and breast related diseases, perform and interpret the study. This allows for maximal integration of breast imaging studies so that the patient achieves the best possible care.
Specialized Testing for Women with a Family History of Breast Cancer
BRCA 1 and BRCA 2 genetic mutations account for 5 to 10% of breast cancers and 10 to 15% of ovarian cancers among white women. A woman who has a BRCA mutation has approximately a 60% lifetime risk of developing breast cancer.