AJR 2003; 180:355-356
© American Roentgen Ray Society
Marking the Cavity Site After Stereotactic Core Needle Breast Biopsy
Ralph L. Smathers1,2
1 Good Samaritan Breast Care Center, Radiological Associates Medical Group, 2410
Samaritan Dr., Ste. 101, San Jose, CA 95124.
2 Mammography Specialists Medical Group, 15559 Union Ave, Ste. 230, Los Gatos,
CA 95032.
Received May 21, 2002;
accepted after revision July 24, 2002.
The author has a financial interest in Vivant Medical, Inc.
Address correspondence to R. L. Smathers.
Introduction
After percutaneous vacuum-assisted stereotactic core biopsy of the breast,
a small radiographically detectable marker is often inserted into the area of
the biopsy to identify the site should the patient require further treatment.
Deployment of a radiographically visible marker at the site of a needle biopsy
allows subsequent needle localization to be performed. Marking is especially
important if the lesion is malignant.
Small stainless steel clips are most commonly used for this purpose but are
sometimes difficult to accurately place at the biopsy site. The data suggest
that the position of metallic clips placed during stereotactic core needle
biopsy may differ substantially from the location of the biopsy site
[1]. For a marker to be useful,
it must remain close to the biopsy site. Studies of the accuracy of clip
deployment show that 2-28% of clips are more than 1 cm from the target
[2,3,4,5,6].
If a deployed clip is attached to compressed breast tissue, the clip may move
considerably after compression on the breast tissue is released because of the
accordion effect. This effect is most prominent in the plane perpendicular to
the plane compressed during the biopsy
[1].
A new marker has been developed that is not attached by pinching or
clipping breast tissue during compression. The Vivant Medical Biopsy Marker
System (Vivant Medical, Mountain View, CA) is an in-dwelling marker for use
after the percutaneous excision of a breast lesion. This unique marker is
designed to be deployed within the biopsy cavity rather than into the
surrounding breast tissue. The marker consists of a radiopaque titanium metal
ring surrounding a bioabsorbable collagen cylinder.
Subjects and Methods
At an outpatient breast center, the Vivant Medical Biopsy Marker System was
used 17 times on 15 patients with mammographically detected lesions. Two
patients underwent biopsies for two separate lesions. All 15 patients had a
stereotactic vacuum-assisted breast biopsy for nonpalpable lesions including
calcifications and masses. All biopsies were performed under digital imaging
guidance on a dedicated prone unit (StereoGuide; LoRad Medical Systems,
Danbury, CT) with a directional, vacuum-assisted biopsy system and an 11-gauge
probe (Mammotome; Ethicon Endosurgery, Cincinnati, OH). After each patient's
procedure, stereotactic images were obtained to check placement of the marker,
and mammograms were obtained in the craniocaudal and true lateral
projections.
The new marker system is a sterile single-patient-use device consisting of
a biopsy marker and a delivery system. The device has been approved by the
United States Food and Drug Administration for marketing. The components of
the biopsy marker system are a plunger, a locking pin, a handle body, an
orientation nub, and the marker (Fig.
1A,1B).
The biopsy marker is a 2-mm titanium ring centered on an absorbable type-1
beef collagen sponge structure
[7]. The marker is compressed
and preloaded inside a sheath tube at the tip of the device. The delivery
system consists of a coaxial deployment mechanism inserted through the
Mammotome probe at the end of the biopsy procedure. Once the marker system has
been positioned, the locking pin is removed, and the plunger is depressed,
ejecting the marker out of the biopsy window of the probe.
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Fig. 1A. —Photographs of Vivant Medical Biopsy Marker System (Vivant
Medical, Mountain View, CA). Device includes plunger (A), locking pin (B),
handle body (C), orientation nub (D), and marker (E). After marker system has
been positioned, locking pin is removed, and plunger is depressed, releasing
marker from outer sheath.
|
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The marker system is not used in any patient who has a history of a
bleeding disorder; is currently receiving anticoagulation therapy; has a
breast infection; or has a known allergy to beef products, collagen, or
collagen products. The titanium marker is compatible with MR imaging using a
1.5-T field strength or less.
Results
The biopsy marker system was easily visualized on stereotactic images after
deployment and on mammograms obtained after the biopsy. In all patients, the
marker (Fig. 1B) was located
within the biopsy cavity. Craniocaudal
(Fig. 2A) and lateral
(Fig. 2B) mammograms showed
that the titanium ring marker was positioned in the center of the stereotactic
biopsy cavity and was surrounded by air radiolucency. The soft-tissue density
within the cavity adjacent to the ring likely results from absorbed fluid or
blood in the collagen cylinder. No unusual bleeding or any other complication
was seen.
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Fig. 2A. —47-year-old woman in good health with abnormal findings on
mammography. She underwent biopsy, site of which was marked with Vivant
Medical Biopsy Marker (Vivant Medical, Mountain View, CA). Craniocaudal
mammogram obtained after biopsy shows that marker is positioned in center of
stereotactic biopsy cavity and is surrounded by air radioluceny.
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View larger version (102K):
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Fig. 2B. —47-year-old woman in good health with abnormal findings on
mammography. She underwent biopsy, site of which was marked with Vivant
Medical Biopsy Marker (Vivant Medical, Mountain View, CA). True lateral
mammogram obtained same day as A shows that marker is positioned near
center of stereotactic biopsy cavity.
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Discussion
This new system differs from other biopsy markers currently in use in
several ways. The metallic marker is titanium rather than stainless steel and,
unlike some clip systems, the marker is deployed with the vacuum turned off.
Whereas some marker delivery systems require retraction of the probe by 5 mm
before delivery, the delivery system for the Vivant marker does not require
retraction of the probe from the original stereotactic coordinates. The
collagen cylinder extends on both sides of the titanium ring. When the marker
is deployed, the collagen cylinder is released into the biopsy cavity.
Portions of the collagen cylinder on both sides of the marker expand to absorb
fluid and stabilize the marker within the cavity. This feature tends to place
the metallic marker centrally in the biopsy cavity and to make the marker
resistant to migration.
The Vivant marker is clearly visible to the naked eye. The radiologist
would readily notice if it failed to deploy or was improperly placed, unlike
some other markers that are so small they can be easily lost or
"disappear" during deployment. Such tiny clips are sometimes lost
down tubing during vacuum aspiration or may get stuck to the edges of the
biopsy window or to the exterior of the needle probe. In our study, the Vivant
marker never disappeared or was poorly positioned in any of the 15 patients.
Marker distances from the biopsied lesion were measured and are still being
collected for a larger group of patients. Descriptions of measurement
techniques, tables, and statistics for the study are beyond the scope and
intent of this article.
In our study, the collagen material used in the Vivant Medical Biopsy
Marker System is similar to that commonly used in surgical and vascular
procedures to control bleeding. The marker has also been successfully placed
using sonographic guidance, but it has not yet been approved for marketing
specifically for that purpose by the Food and Drug Administration.
Placement of the Vivant Medical Biopsy Marker System is an efficient and
simple method of marking the site of a biopsy cavity. The marker has shown a
negligible incidence of accordion effect or disappearance. It may be a more
precise marker of a biopsy cavity in patients requiring follow-up studies or
interventional procedures.
References
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Introduction
Subjects and Methods
