| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Experimental Studies |
1 From the Division of Surgical Oncology (P.I.H., A.E.G.), and the Joyce Eisenberg Keefer Breast Center (R.J.B.), John Wayne Cancer Institute at Saint John’s Health Center, 2200 Santa Monica Blvd, Santa Monica, CA 90404. Received September 17, 1999; revision requested October 14; revision received November 12; accepted December 6. Supported in part by the Ben B. and Joyce E. Eisenberg Foundation and the Fashion Footwear Association of New York. Address correspondence to A.E.G. (e-mail: giulianoa@jwci.org).
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
MATERIALS AND METHODS: Mock breast surgery was performed by cauterizing bovine liver or fresh, normal, human breast tissue. The cautery tip was rubbed against a cleaning pad five to 20 times in the manner used intraoperatively and was touched on separate breast tissue specimens two to six times. Specimen radiography was then performed. Thirty-six breast specimens were used in three experiments, including 28 used for the experimental conditions and eight control specimens.
RESULTS: Particles collected from the cleaning pads resembled microcalcifications. After cauterization of liver, breast tissue, or both, in series, particles transferred from the cautery tip to breast tissue specimens could be identified on specimen radiographs. Transfer of particles after cautery of breast tissue occurred with increased numbers of rubs and specimen contacts.
CONCLUSION: Radiopaque aluminum oxide particles from abrasive cautery-tip cleaning pads can be dislodged and transferred to breast tissue during surgery. Scrutiny of high-detail, spot-compression, magnification mammograms will help identify these particles. Simple measures to mitigate particle transfer during breast surgery can prevent this problem and obviate a potential second procedure to remove particles mistaken for microcalcifications.
Index terms: Breast neoplasms, experimental studies, 00.459, 00.46 • Breast neoplasms, radiography, 00.46, 00.93 • Breast neoplasms, surgery, 00.459, 00.46
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Several hypotheses have been raised with regard to the origins of metallic particles in the breast. Particles have been identified after wire localization, but the exact origin of this rare event and whether the particles were acquired during actual wire localization or surgical biopsy were reported to be unknown (5). A braided type of hook-wire device, which purportedly can shed metallic fragments after the wire has been cut, has also been implicated (6). This seems unlikely, however, because the skin incision is performed after the excess wire is cut, and, after incision, the exposed breast parenchyma is excised with the wire in place. Finally, the use of 90° front-notch angle-core biopsy needles as a cause for metallic fragments has been reported to the U.S. Food and Drug Administration (4,7). However, with the use of directional vacuum-assisted and other needle biopsy devices, the phenomenon still has been observed. Overall, then, another explanation for metallic particles in the breast may be more likely.
We have observed metallic particles in the breasts of two patients without a history of gunshot wounds, gold therapy, or antecedent core biopsy or localization procedures prior to breast surgery. We deduced that the acquisition of metallic particles may have occurred during surgical excision, particularly because this procedure was the common denominator between excisional breast biopsies performed with or without localization or prior core biopsy. After investigating all materials and instruments used for excisional breast surgery during these two cases, we identified a reproducible and preventable probable cause for this finding; namely, the displacement of particles from abrasive cleaning pads used during routine surgery to cleanse the electrocautery tip of charred coagulum. This in vitro study was conducted to determine if cleaning a cautery tip by using an abrasive cautery-tip cleaning pad can dislodge radiopaque particles that can be transferred to breast tissue during surgery.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
To determine if the particles could be transferred from the cleaning pad to the surgical field during typical use of electrocautery at surgery, in vitro experiments were performed with fresh breast tissue collected from four young healthy women who underwent reduction mammoplasty. Specimens were obtained from the portions of breast tissue prior to fixation for microscopic analysis and were cut into pieces approximately 3 x 5 cm in area. All patients had undergone preoperative mammography, the results of which were reviewed by an experienced mammographer (R.J.B.), and no microcalcifications were present. The institutional review board was consulted, and approval was obtained to perform in vitro experiments with the human breast tissue.
Three experiments were performed with two types of tissue that were cauterized to simulate normal surgical conditions. Electrocautery for each experiment was performed by using an electrosurgical unit (Force F/X; Valleylab, Boulder, Colo) at a pure coagulation setting of 40 W. New cleaning pads were used for each experiment. A specimen imager (Microfocus; GE Medical Systems, Milwaukee, Wis) was used to obtain all specimen radiographs. Specimen radiographs were examined for radiopaque particles by a radiologist (R.J.B.) blinded to the experiment performed and to the identity of the control specimens.
Experiment 1
In the first experiment, electrocautery was used to coagulate the surface of bovine liver. This experiment was chosen to simulate direct cautery of a bleeding vessel, which is a routine technical maneuver performed during breast and other surgery. The liver contains an abundance of red blood cells, lipids, proteins, and plasma within its tissue, and we thought it was an approximate substitute for bleeding tissue that, moreover, did not necessitate the use of live experimental animals. The liver was placed on an adhesive grounding pad where it was electrocauterized for 5 seconds. The cautery tip then was rubbed on a cleaning pad and lightly touched to a breast specimen as though the breast specimen were being cauterized.
Two variables were manipulated: the number of cleaning pad rubs, which was increased in increments of five up to 20, and the number of contacts with the breast specimen, which was increased in increments of two up to six. For each variation of cleaning pad rubs and cautery-tip contacts, a separate breast specimen was used. Radiographs of the 12 breast specimens used in this experiment were then obtained, and the presence of radiopaque particles was recorded for each specimen.
Experiment 2
The second experiment was performed in an identical fashion to experiment 1, with breast tissue substituted for liver, to assess if particle transfer could occur after cauterization of breast tissue. A piece of breast tissue was placed on an adhesive grounding pad where it was electrocauterized for 5 seconds. The cautery tip then was rubbed on a cleaning pad and lightly touched to a different breast specimen as though the second breast specimen was being cauterized.
As in experiment 1, two variables were manipulated: the number of cleaning pad rubs, which was increased in increments of five up to 20, and the number of contacts with the breast specimen, which was increased in increments of two up to six. Radiographs of the 12 breast specimens used in this experiment were obtained, and the presence of radiopaque particles was recorded for each specimen.
Experiment 3
In the third experiment, the maximum numbers of breast contacts and cleaning pad rubs used in the first two experiments were assessed after cauterization of both breast and liver tissue. Occasionally during breast surgery, especially during a medial excision, perforating arteries may be transected and cause troublesome bleeding that necessitates repetitive use of cautery and the cleaning pad. Experiment 3 was an attempt to simulate that situation. Breast tissue and then liver were serially electrocauterized for 5 seconds. The cautery tip then was rubbed 20 times on a cleaning pad and touched six times on a different breast specimen. This sequence was performed in four breast specimens. The breast specimens were radiographed at the completion of the experiment, and the presence of radiopaque particles was recorded for each specimen.
Control Specimens
One control breast specimen was radiographed without being touched with a cautery tip. For experiment 1, three breast specimens were contacted with the cautery tip two, four, or six times after cautery of liver but without use of the abrasive cleaning pad and were then radiographed. For experiment 2, three breast specimens were touched with the cautery tip two, four, or six times after cautery of breast tissue without cleaning of the tip on the abrasive cleaning pad and were then radiographed. Finally, one control breast specimen was used in experiment 3; it was touched with the cautery tip after cautery of liver and breast tissue without cleaning of the tip with the abrasive cleaning pad and was then radiographed. Thus, a total of eight breast specimens were used as control specimens.
Recent Patients
We identified radiopaque particles on mammograms in two recently encountered patients who underwent breast surgery. In the first patient, calcifications seen at screening mammography, which were diagnosed as ductal carcinoma in situ on the basis of stereotactic core-needle biopsy results, were removed at segmental mastectomy, and particles were identified on mammograms obtained 4 months later at the surgical site near an area of actual clustered calcifications. Magnification-view mammograms were obtained. The second patient presented with a palpable mass. Preoperative mammograms revealed no microcalcifications. A benign breast mass was excised without any localization procedure. At follow-up mammography 12 months later, radiopaque particles at the excision site were identified.
Electrocautery and an abrasive cautery-tip cleaning pad were used during surgery in both patients. Routine quality control review procedures, as well as a review of all radiographs obtained on the same day that each patient underwent mammography, identified no source of film artifact. The mammograms were examined by one of the authors (R.J.B.) in a manner identical to that for the three experiments.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
|
|
|
|
|
|
|
In the first recently encountered patient, after careful analysis, the particles showed increased attenuation of x-ray photons relative to the attenuation of calcific particles of the same size. The increased attenuation imparted a metallic appearance to the particles on the mammogram. The magnification-view mammogram revealed that the particles had greater radiopacity than had adjacent actual calcifications (Fig 5). In fact, the metallic particles appeared remarkably similar to those depicted in Figures 1 –4, particularly Figure 4b. In the second patient, the mammogram showed metallic particles with high radiopacity (Fig 6). These findings were similar to those seen at the in vitro experiments, particularly those shown in Figure 4a. Indeed, on close inspection, the cleaning pad particles resembled those seen in cases of gunshot foreign-body remnants.
|
|
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
A simple accessory often used by the surgeon during tissue cauterization is an abrasive cleaning pad, a convenient sterile device that can be used to mechanically clean the cautery tip. The abrasive surface of cautery-tip cleaning pads is composed of aluminum oxide or silicon carbide, much like the surface of sandpaper used in metal shops. After the cautery tip accumulates coagulated debris, it is rubbed against the abrasive cleaning pad and used again within the wound, a sequence that may be repeated during surgery. The results of this study demonstrate that the action of cleaning a cautery tip on an abrasive cleaning pad during surgery can dislodge radiopaque aluminum oxide particles that can be transferred to breast tissue on contact with the cautery tip.
This complication has, to our knowledge, gone unreported in the medical literature and probably accounts for the metallic fragments reported by others and erroneously attributed to unlikely causes. Such deposition may occur during surgery in other organs but is noticeable during mammography because of the low kilovoltage used to image the breast and the importance of identifying microcalcifications, which may be simulated by small metallic particles other than calcium particles.
What may seem a minor complication can lead to additional and unnecessary breast surgery. Specimen mammography after excisional breast biopsy may show the factitious microcalcifications and mislead the mammographer and surgeon into the belief that a satisfactory excision has been performed, only to have the suspicious-looking calcifications appear at subsequent mammography. More disconcerting is that transfer of these particles into the breast is possible with the repetitive coagulation and cleaning that may occur during lumpectomy. The introduction of these particles into the lumpectomy cavity may therefore lead to unnecessary additional surgery to excise apparent microcalcifications that were introduced unknowingly by an otherwise well-executed breast-conservation operation or biopsy.
Although cleaning pads are usually used sparingly at each operation because breast excisions generally are not excessively bloody, our results showed that transfer can occur with minimal cleaning pad rubs and breast contacts. When particles from abrasive cleaning pads are identified on postoperative mammograms, the specific mammographic features should allow a conservative observational approach rather than a second operation, especially when the radiologist is aware of this artifact.
Mammography after breast-conservation surgery followed by radiation therapy for malignancy reveals certain features in the breast that change over time; these features include skin changes, architectural distortion, and regional density. The frequency of calcifications has been shown to either increase over time or remain relatively stable 5 years after treatment, with an incidence of 1%–11% within the 1st year after surgery (8–10). The presence of calcifications after surgery to excise ductal carcinoma in situ is particularly important because of a recent report (11) that all recurrences manifested mammographically as calcifications. On the other hand, biopsy results from these calcifications at the lumpectomy site within the 1st year show benign findings in nearly half of all cases (9). Moreover, when mammography was performed in 120 patients after a mean of 6 weeks after breast-conservation surgery for cancer but before radiation treatment, calcifications were present at the surgical site in 8% of patients, half of which calcifications were proved at biopsy to be benign (12). It is possible that some cases of benign postoperative breast calcifications were, in fact, particles from cautery-tip cleaning pads. Because biopsy will likely be prompted if calcifications are seen at the lumpectomy site in either the period after surgery and before radiation therapy or during surveillance, knowledge of the presence of the cautery-tip cleaning pad artifact and attempts to distinguish it from truly suggestive calcifications becomes an essential component of diagnostic evaluation.
There are other more commonly recognized reasons for factitious microcalcifications detected at mammography. External substances such as antiperspirants, powders, soaps, and dermal tattooing also can cause artifacts that mimic intramammary calcifications; these should be readily appreciated at mammography performed after the breast has been wiped clean or by means of correlative physical examination (13,14). Suture calcification and foreign-body reaction to suture material in the irradiated breast have been documented as mimicking cancer recurrence in the breast, but these artifacts are easily recognizable (15–17). The abrasive particles from cautery-tip cleaning pads, however, are introduced deep within the breast parenchyma and may not be easily recognizable as factitious, which thereby raises the risk of unnecessary surgery.
Practical application: Caution should be exercised when abrasive pads are used to clean cautery tips during breast surgery, because of the serious implications of a mammographic misdiagnosis of microcalcifications. In any other organ, transfer of these particles would not cause diagnostic confusion and more than likely would be undetectable. The cautery tip may be cleaned with a peroxide-soaked sponge. As an alternative, commercially available Teflon-coated cautery tips that inhibit the accumulation of coagulated debris and do not require frequent abrasive cleaning could be used.
The radiologist reviewing postoperative mammograms, especially those obtained after breast-conservation surgery performed because of malignant disease, should be aware of this artifact caused by the intraoperative use of abrasive cautery-tip cleaning pads. Our results have demonstrated the likely origin of such an artifact and provide a basis for constructive discussion between the radiologist and surgeon to avoid such a complication after future operations. In addition, awareness of this artifact should enable the radiologist to use high-detail, spot-compression, magnification views to help distinguish calcific particles from other metallic elements that can cause such an artifact.
|
FOOTNOTES |
|---|
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
This article has been cited by other articles:
|
|
 |
|
  J. A. Harvey, R. E. Hendrick, J. M. Coll, B. T. Nicholson, B. T. Burkholder, and M. A. Cohen Breast MR Imaging Artifacts: How to Recognize and Fix Them RadioGraphics, October 1, 2007; 27(suppl_1): S131 - S145. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| RADIOLOGY | RADIOGRAPHICS | RSNA JOURNALS ONLINE |
