Tuesday, January 1, 2008

Stereo tactic biopsy

Dr. Butler did not think my mammo looked all that "suspicious" but he said he would not overrule the KP radiologist. so the next step was to get a biopsy,
in my case a stereotactic breast biopsy.


There's lots of info on line about the procedure, but what I really wanted was a picture of the table. There is a good one in the booklet they gave me, so I may try to get that
scanned in.

What does the equipment look like?
A specially designed table is used for stereotactic biopsy. The patient is lying face-down with her breast projecting through a hole in the table. The actual biopsy is done below the table after raising it to gain access to her breast. The procedure also may be done with the patient upright in a chair. An upright study may be best for those women who might have difficulty climbing onto the table or who are unable to lie prone for any reason. You must not move during the procedure.

A paddle-shaped instrument compresses the breast during biopsy. (Like a mammogram) A tray is nearby containing all of the equipment necessary for the biopsy.

Actually in my case the computer was across the room. The procedure was done by a nurse and a doctor. There were two places of concern, and they tried very hard
to get lined up for one punch, but it never happened. What should have taken about 5 minutes took over 30 minutes and by then I was very cranky.

In addition to the specialized equipment needed for x-ray-guided breast biopsy, specially trained technologists and physicians perform the procedure. The images are obtained not with x-ray-exposed film as in conventional mammography, but using computerized or digital imaging in place of a film cassette. This reduces x-ray exposure to the breast and also permits the images to be viewed on a computer monitor seconds after exposure—compared with the several minutes needed to develop x-ray film. The principle of stereotactic biopsy is that a lesion can be located precisely in three dimensions by calculating its apparent change in position on angled x-ray images. The first x-ray locates the abnormality in the breast, after which two stereo views are obtained, each angled 15 degrees to either side of the initial image. The physician then marks the lesion electronically on the stereo images. The computer calculates how much the lesion's position appears to have changed on each of the stereo views, and in this way is able to determine its exact site in three-dimensional space.

The biopsy instrument used in this procedure is called a vacuum-assisted device (VAD), which consists of an inner needle with a trough extending from it at one end and an overlying sheath. When the sheath is retracted, a vacuum is used to pull breast tissue into the needle trough. The outer sheath rapidly moves forward to cut the tissue and collect it in the trough.

An advantage of the VAD is that the needle is inserted only once into the breast without having to withdraw the needle after each sampling. Biopsies are obtained in an orderly manner by rotating the probe, assuring that the entire region of interest will be sampled.

The first step is to clean the skin and inject a local anesthetic. A small nick is made in the skin and the tip of the biopsy needle is advanced to the previously calculated site of the lesion. At this point stereo images are again obtained to confirm that the needle tip is actually within the lesion. Usually six to 12 samples are collected when the VAD is used. Then a final set of images is obtained. If they show that the lesion has been mostly or completely removed, a small clip is left at the biopsy site so that it can be easily located if the lesion proves to be cancer. Once the biopsy is complete the skin opening is covered with a dressing; it need not be sutured. You will be told to avoid strenuous activity for 24 hours after returning home, but then usually will be able to resume normal activities

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