Online Management of Breast Diseases Patient Education |  Physician Guidelines |  Treatment Index
News |  TransMed |  E-Mail |  Disclaimer

STEREOTACTIC BREAST BIOPSY

 

 

STEREOTACTIC IMAGE – GUIDED BREAST BIOPSY

Priscilla D. Wong, M. D.
Director, Providence Breast Center
Burbank, CA

When a breast lesion is not palpable but detected on a mammogram and diagnosed to be suspicious for malignancy, the lesion must first be localized using image guidance and a biopsy must be performed for tissue diagnosis.

Traditionally, the lesion undergoes needle localization by a radiologist followed by open excisional biopsy under general anesthesia by a surgeon in the operating room. In recent years, less invasive techniques have been developed and are being used more frequently. One of the new techniques is stereotactic breast biopsy.

IMAGING TECHNIQUE

The breast is compressed just as in regular mammography, except the compression paddle has a window. The x-ray tube can be positioned perpendicular to the image detector as well as +15 degrees and –15 degrees to the perpendicular. Localization of a specific lesion within a breast, by x-ray imaging, is based on measurements of the position of the lesion on two images of the breast taken from different angles (+15 degrees and –15 degrees). Such a set of images is referred to as a stereo pair. The radiologist selects the center of the lesion, a mass or specific calcifications of a cluster. A computer generates the X, Y and Z coordinates of the targeted lesion. The Z coordinate is the depth of the lesion from the skin. Some stereotactic units are upright with the patient sitting during the procedure. Other units include a table where the patient can lie prone with the breast hanging from a hole in the table. The prone table is more comfortable for the patient and decreases the possibility of motion.

BIOPSY DEVICES

Once the stereo pair is obtained and the exact location of the lesion is calculated, any of several devices may be employed to obtain tissue sample. The devices differ in the size of the tissue samples obtained the mechanism of obtaining the samples and whether the tissue sampling is noncontiguous, contiguous or possibly complete removal of the lesion. These devices include 1) a spring loaded core biopsy needle (14G), 2) a vacuum-assisted core biopsy device (Mammotome 14G or 11G and MIBB 8G) and 3) a larger core device (ABBI, 5mm, 10mm, 15mm, and 20mm). Local anesthesia is used with these devices and a skin incision is made to accommodate the device to be used.

  • Spring Loaded Biopsy Needle

A 14 gauge core biopsy needle can be deployed by a spring loaded device. Each core tissue sample is obtained with a separate insertion into the incision site, and variations of the X and Y coordinates for noncontiguous sampling of the lesion.

  • Vacuum-Assisted Core Biopsy Device

The vacuum-assisted core biopsy device can more easily obtain core samples that are generally larger than the spring loaded core biopsy needle. It allows multiple contiguous tissue sampling with a single insertion of the needle into a lesion.

A) Mammotome

This core biopsy device may be used with a 14 gauge or 11 gauge needle. The core notch is connected to vacuum suction so that more tissue may be obtained than the spring loaded core biopsy needle. Each core sample is extracted through the needle using vacuum suction. This enables a one-time insertion of the needle through the lesion, followed by multiple contiguous directional sampling of breast tissue. The needle is inserted through a tiny incision (approximately 5mm) in the skin. A small metallic clip may also be deployed through the 11G needle to mark the biopsy site in case therapeutic lumpectomy and/or radiation therapy need to be performed for invasive cancer.

B) MIBB (Minimally Invasive Breast Biopsy) Device

A vacuum-assisted core biopsy device, similar to the Mammotome, using an 8 gauge needle and some design modification. Presently, this device has not yet been FDA approved.

First the radiologist localizes the lesion with a needle in the center of the device. Subsequently a surgeon removes a core of tissue from the breast using a circular oscillating blade which is advanced concentrically over the initial localization needle. ABBI assemblies are available which can provide core tissues of 5mm, 10mm, 15mm, or 20mm in diameter. The procedure is performed through a skin incision, large enough to accommodate the blade, made under local anesthesia and sutured closed by the surgeon at the completion of the procedure. Presently, the ABBI device has been FDA approved for diagnostic biopsy only. This technique has the potential to completely excise small lesions from the breast with clear histologic margin.

ABBI SYSTEM

Each of the above stereotactic core biopsy procedures can be performed on an outpatient basis under local anesthesia with the patient able to leave within an hour after completion of the biopsy. The localization and biopsy of the lesion are more accurate since there is direct visualization of the lesion during the procedure. This allows for directional adjustment if necessary. The procedures are less invasive and less disfiguring than open excisional biopsy and yield equal diagnostic accuracy. Since up to 80% of breast biopsies are benign, stereotactic breast core biopsy is an attractive alternative to open excisional biopsy for early diagnosis of breast cancer.

Copyright 98 - TransMed Network