Image-Guided Breast Biopsy

A breast biopsy removes thin cores of tissue that a pathologist examines under the microscope. In an ultrasound-guided core biopsy, the radiologist watches the needle on the ultrasound screen as it enters the lump and takes several samples, each about the size of a grain of rice. Some changes, especially small calcifications, show only on a mammogram; these are sampled with stereotactic guidance, in which mammogram images taken from two angles calculate the exact position, or with tomosynthesis guidance, which uses three-dimensional mammogram images. These biopsies usually use a vacuum-assisted needle, which draws tissue into the needle and collects larger samples through a single insertion. An MRI-guided biopsy is used for an area visible only on breast MRI, with contrast dye injected to show it. In each case a small metal marker clip, about the size of a sesame seed, is usually left at the biopsy site so that it can be found later on imaging or during surgery.

A biopsy is recommended when a breast lump or an imaging finding cannot be confidently classed as benign from its appearance alone. Typical reasons are a new lump, a solid mass on ultrasound with features that are not clearly benign, a cluster or line of calcifications on a mammogram, an area of distorted tissue, or a new enhancing area on MRI. Radiology reports often use a scoring system called BI-RADS, and findings scored as suspicious are usually biopsied, while findings judged probably benign may be followed with a repeat scan in about six months instead. A biopsy may also sample a lymph node in the armpit that looks abnormal, or check a change in a breast previously treated for cancer. Biopsy is also used before cancer treatment to obtain the tissue tests, such as hormone receptors and HER2, that guide chemotherapy, hormone therapy and targeted therapy. A simple cyst that looks typical on ultrasound usually needs no biopsy.

For an ultrasound-guided biopsy you lie on your back or side. The skin is cleaned and numbed with local anaesthetic, which stings briefly, and the deeper tissue is numbed too. A small nick of a few millimetres is made, and the radiologist guides the needle into the area while watching the screen. Several samples are taken; the biopsy device makes a click as it fires. For a stereotactic or tomosynthesis biopsy you usually lie face down on a special table with the breast through an opening, or sit, while the breast is held gently compressed, and the samples are taken through one insertion with a vacuum-assisted needle. For an MRI-guided biopsy you lie face down in the scanner, and contrast dye is injected through a vein. After sampling, the marker clip is placed, firm pressure stops any bleeding, and the nick is closed with adhesive strips. A mammogram is often taken afterwards to confirm the clip position.

Almost anyone with a finding that needs a diagnosis can have an image-guided biopsy, including pregnant and breastfeeding women, in whom ultrasound guidance is preferred. Tell the team about blood thinners, because some may need to be paused for a short time on medical advice, and about allergies, especially to local anaesthetic or MRI contrast dye. MRI-guided biopsy is not suitable for people with some implanted devices or severe claustrophobia, and kidney function may be checked before contrast is given. On the day, wear a two-piece outfit, avoid deodorant or powder under the arms and on the breasts if a mammogram is planned, and bring a supportive bra. You can eat normally. International patients should send previous mammograms, ultrasound and MRI images, not only reports, in advance, so that the radiologist can review them, choose the guidance method and, if needed, repeat imaging on arrival before the biopsy.

After the biopsy you can usually leave within about 30 minutes. The breast may feel sore and bruised for a few days, and an ice pack and simple painkillers help. Wearing a supportive bra, including at night for the first day, reduces discomfort. Avoid heavy lifting, vigorous exercise and swimming for about 24 to 48 hours. Keep the adhesive strips dry for a day or two. Most people return to work the same or the next day. Results usually take a few days to about a week, longer if additional tests are needed. Flying is generally fine the next day, but consider staying until the results are ready, so that you can discuss them in person and, if cancer is found, begin planning treatment, including further scans, without a second trip. If you leave earlier, agree in advance how and when the results will be shared and who will explain them.

Image-guided breast biopsy is safe and well tolerated. Bruising and tenderness are common and settle within days. A collection of blood (haematoma) under the skin can form and usually resolves by itself. Infection is rare. Some people feel faint during or after the procedure. Very rarely, a biopsy close to the chest wall can cause air to leak around the lung, which is why imaging guidance is used throughout. The pathology report usually describes the tissue in plain categories: normal or non-diagnostic tissue, a benign condition such as a fibroadenoma, a lesion of uncertain potential that often needs removal or further sampling, a finding suspicious of cancer, or cancer with its type and receptor results. The radiologist checks that the result matches the imaging; if it does not, a repeat biopsy or a small operation to remove the area may be advised. Most breast biopsies show benign changes.