Stereotactic Breast Imaging
STEREOTACTIC BREAST BIOPSY
Jerry K. Myers, M.D.
Stereotactic breast imaging makes possible the localization of breast lesions to a resolution of approximately 1 millimeter. This technology utilizes a process called digital spot mammography to visualize and precisely locate areas within the breast that are only seen mammographically and are not able to be palpated. Once Stereotactic localization is accomplished, the area may be immediately biopsied or in some cases completely removed during the Stereotactic procedure. This technology also allows precise localization of lesions within the breast that need operative removal.
The most common application of Stereotactic imaging is the needle core biopsy. This process is not designed to completely remove the lesion (area within the breast to be evaluated), but to sample (biopsy) the area to aide in the diagnosis. This sampling can be done utilizing one of several different biopsy drivers attached to the Stereotactic machine. Each driver is designed to remove tissue for diagnosis in a slightly different way. The Tru-cut device is the least invasive, followed by the Vacuum-Assisted (minimally invasive biopsy device), and then the ABBI biopsy device which is the most invasive.
The needle core biopsy samples the lesion – it does not therapeutically remove the lesion. Obviously, only the tissue removed can be pathologically evaluated – so theoretically one cannot be 100% sure of the diagnosis of the remaining tissue. This diagnostic limitation must be understood by anyone undergoing needle core biopsy. The same follow-up of the abnormality is performed as if no biopsy was done. The biopsy simply aides the follow-up process by giving some objective information as to the breast abnormality noted on the mammogram. A negative needle core biopsy for cancer can never be considered 100% diagnostic. Only complete removal of the lesion assures the diagnosis.
Thus, needle core biopsy is not for everyone. It is ideal for the patient who wants to try to avoid an open surgical procedure of a minimally suspicious lesion, and at the same time feel better about the diagnosis during the follow-up process. These are lesions that are commonly recommended for mammographic follow-up in 4-6 months and then removed only if a suspicious change occurs. However, even with mammographic follow-up recommended, many patients prefer to remove the lesions and not follow them. Now, with biopsy information obtained via Stereotactic sampling, some of these patients may elect to follow these minimally suspicious areas – thus avoiding a surgical procedure.
The Tru-cut biopsy device is utilized for most of the needle core samplings. It is simple to use and, being the least invasive of all devices, has the least potential problems to the patient. Problems are uncommon. However, anytime invasion of tissue occurs, complications such as bleeding, wound hematomas, and wound abscesses or infection can occur. These may be only minimal nuisances or major enough problems to require open surgical procedures to control the problem. The most common problem to understand is that the sampling is never considered 100% diagnostic. Problems are averted here by the same careful follow-up as if the sampling never occurred.
The Vacuum-Assisted (minimally invasive breast biopsy device) removes a larger sample of breast tissue and thus, carries a slightly greater incidence of the wound problems noted above. Because of the larger breast sample, it is more ideal than the Tru-cut for biopsying areas such as calcifications. Even though more tissue is removed, Vacuum-Assisted sampling is still not considered 100% diagnostic, - so if one wants or needs complete diagnosis, open complete excision must still be done.
The ABBI device can remove the largest tissue samples of the above devices. It, however, is more invasive with a significantly higher complication rate than the Tru-cut or Vacuum-Assist. Since the device can take out large cores, small lesions can sometimes by completely removed. However, wound complications must be anticipated more with this technique, and operative intervention to suture bleeding vessels or drain hematomas and infection is significantly more common with this technique. Because of the potential complications with the ABBI core biopsy – ABBI is definitely not for everyone. One should not elect it unless the potential complications are fully understood and their possibilities accepted. Careful surgical dissection in the operating room is still an excellent alternative for many patients and breast surgeons when considering these larger areas to be excised.
The technique for Stereotactic localization and biopsy is relatively simple. There is virtually no preparation for the patient and it can be conveniently done in our breast clinic with no hospital admission. As stated, complications are minimal, especially with the more minimally invasive procedures. The incisions needed are limited to the needle sizes and thus small dressings or Band-Aids are usually all that are needed. Sometimes pressure dressings are needed when more aggressive biopsies are done. If the larger ABBI excisions are performed, suturing of the skin is needed just as would be done in any other larger opening of the skin for surgery.
The procedure itself requires local anesthesia – so an absolute contraindication for the procedure is an allergy to local anesthetics (xylocaine, Lidocaine, Marcaine, etc.). For most patients, there is minimal discomfort in doing the procedure. However, as in any procedure requiring needle injections and needle biopsies, there may be varied degrees of discomfort that may vary from patient to patient. This must be understood prior to making a decision to undergo any procedure under local anesthesia. The procedure also requires lying prone on the Stereotactic table for 30-45 minutes with the breast in a mammogram compressive device, so some discomfort may occur with this positioning. This is rarely a significant problem, but may limit the procedure for some patients.
Occasionally, the lesion noted on the mammogram cannot be seen or adequately identified to Stereotactically biopsy it. Reasons for this may vary. The lesion could have gotten significantly smaller (as a cyst or fibrocystic lesion) or the technique just simply could not adequately localize the lesion to biopsy it. If the lesion cannot be identified, then obviously it cannot be sampled. In these instances – a biopsy is not done and adequate follow-up ensues.
