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DOI: 10.1148/radiol.2321012003
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(Radiology 2004;232:205-210.)
© RSNA, 2004

Breast Imaging

Breast Biopsy: Multicenter Study of Radiofrequency Introducer with US-guided Handheld System—Initial Experience1

Nathalie Duchesne, MD, FRCP(C), Steve H. Parker, MD, Anita J. Klaus, MD and Mary Lou Mooney, MS

1 From the Department of Radiology, Hôpital du Saint-Sacrement, Québec City, Canada (N.D.); Sally Jobe Breast Center, Englewood, Colo (S.H.P.); Department of Radiology, Community General Hospital, Syracuse, NY (A.J.K.); and Seno Rx, Aliso Viejo, Calif (M.L.M.). From the 2001 RSNA scientific assembly. Received December 7, 2001; revision requested February 20, 2002; final revision received December 15, 2003; accepted January 5, 2004. Supported by SenoRx. Address correspondence to N.D., Ottawa Regional Women’s Breast Health Center, 200 Melrose Ave, Ottawa, ON, Canada KIY 4K7 (e-mail: nduchesne@ottawahospital.on.ca).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
PURPOSE: To evaluate the utility of a radiofrequency (RF) introducer in placement and use of a handheld breast biopsy system during ultrasonography (US)-guided breast biopsy.

MATERIALS AND METHODS: In three institutions from September 2000 through June 2001, 99 patients were scheduled for US-guided breast biopsy with the handheld system. Patients were randomly assigned to undergo biopsy with the handheld system alone (control group, 50 patients) or with the RF introducer and the handheld system (treatment group, 49 patients). Investigators compared the ability of the radiologist and pathologist to obtain a histologic diagnosis, ease of tissue penetration, procedure time, and pain. Patients assessed their pain level after the procedure and at 1, 7, and 30 days after biopsy.

RESULTS: The RF introducer provided easier penetration (treatment group mean score, 1.6; control group, 2.4), particularly in patients with dense breasts (treatment group, 1.0; control group, 2.9) on the basis of a five-point scale (1 = very easy, 5 = extremely difficult). A histologic diagnosis was obtained in all cases, and no RF-induced artifact was reported. Average biopsy procedure time for treatment and control groups was not significantly different. Average patient pain levels were comparable between groups for each evaluation interval. Clinical complications in four treatment patients and three control patients were minor and resolved spontaneously.

CONCLUSION: The RF introducer may serve as a useful adjunct to the handheld biopsy system by facilitating penetration of breast tissue without causing any deleterious effects for the patient or the biopsy specimen.

© RSNA, 2004

Index terms: Biopsies, technology, 00.1261, 00.12985 • Breast, biopsy, 00.1261, 00.12985, 00.30 • Breast neoplasms, diagnosis, 00.30 • Radiofrequency (RF) ablation, 00.1269 • Ultrasound (US), guidance, 00.12985


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Since 1988, several breast biopsy instruments have become available that allow biopsies to be performed with ultrasonographic (US) guidance and require no more than one insertion of the biopsy instrument into the breast. Surgical biopsies can cause disfigurement and require longer recovery times. In biopsies performed with the newer instruments, which incorporate a small probe and/or cutter that traverses the breast through a small incision, a physician can retrieve specimens from a previously identified lesion and obtain an accurate histologic diagnosis. However, given the differences in breast tissue composition among patients—from tough dense connective tissue to soft fatty tissue—the force required to push these probes into the breast may vary from heavy to light depending on tissue type. The biopsy probe may not only encounter resistance from the breast tissue but also may be deflected away from the target lesion by breast tissue or the lesion itself. These factors may lead to inaccurate placement of the probe.

A radiofrequency (RF) introducer is an electrosurgical device intended for use in conjunction with a handheld breast biopsy system. The RF introducer is used to penetrate the breast by means of RF cutting to reach the target lesion and to function as an entry portfor insertion of the probe of a biopsy device. The RF introducer used in this study is not a new type of biopsy device but is essentially an introducer for a handheld breast biopsy system.

The purpose of this study was to evaluate the utility of an RF introducer in placement and use of a handheld system during US-guided breast biopsy.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Devices
The RF introducer used in this study (Easy Guide; SenoRx, Aliso Viejo, Calif) with the handheld breast biopsy system (Mammotome; Ethicon Endo-Surgery, Cincinatti, Ohio) is a monopolar electrosurgical device that employs the "pure-cutting" technique and is similar to electrosurgical devices used in breast surgery since the late 1920s. As with the Bovie electrocauterization unit and other electrosurgical instruments used in the breast, the RF introducer incorporates an electrosurgical cutting tip (1–5). The RF introducer received clearance from the U.S. Food and Drug Administration and is commercially available in the United States, Canada, and the European Union.

The RF introducer comprises an obturator and a cannula made of medical-grade polymers (Fig 1a). A stainless steel RF cutting tip on the obturator facilitates US-guided entry into the breast. During use, the introducer is attached to a standard electrosurgical hand piece or cord and is powered with a standard electrosurgical generator with a patient return pad.



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  		Figure 1a. (a) RF introducer (large open arrow) with stainless steel-tip electrode (small open arrow) for delivery of RF energy to facilitate tissue penetration. In position in the breast, obturator (thick solid arrow) is removed from cannula (thin solid arrow) to allow insertion of probe of handheld breast biopsy system. (b) Outer cannula (open arrow) of RF introducer has longitudinal aperture (solid arrow) at distal end that was designed to mate with aperture in probe of handheld system.

 


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  		Figure 1b. (a) RF introducer (large open arrow) with stainless steel-tip electrode (small open arrow) for delivery of RF energy to facilitate tissue penetration. In position in the breast, obturator (thick solid arrow) is removed from cannula (thin solid arrow) to allow insertion of probe of handheld breast biopsy system. (b) Outer cannula (open arrow) of RF introducer has longitudinal aperture (solid arrow) at distal end that was designed to mate with aperture in probe of handheld system.

 
The RF introducer is inserted into breast tissue to the target lesion by using RF energy. The recommended generator power setting for insertion into the breast is 90 W in the pure-cutting mode. The obturator of the device is removed, and the cannula remains in the breast to provide a passageway through which the probe of the handheld breast biopsy system is inserted with US guidance. The outer cannula of the RF introducer has a longitudinal aperture at its distal end that was designed to mate with the aperture in the probe of the handheld system (Fig 1b). Once the system probe is situated in the outer cannula of the RF introducer, tissue samples are collected through the aperture in a manner that has been previously described (6,7).

To ensure that investigators were adequately trained to use the RF introducer, a mandatory training program, which comprised the penetration of "phantom" (turkey breast) target lesions, was required at each institution.

All breast biopsies were guided with US (Logiq 500; GE Medical Systems, Milwaukee, Wis).

Study Design and Patient Recruitment
This prospective, parallel arm, randomized, multicenter clinical trial was conducted in three sites. The local institutional review boards approved the study, and all enrolled patients signed an informed consent form.

Between September 2000 and June 2001 in the three sites, 99 patients were scheduled to undergo US-guided breast biopsy. They were randomly assigned (1:1) to a biopsy procedure performed with either the handheld breast biopsy system with the RF introducer (treatment group) or with the biopsy system alone (control group).

Patients who were included in the study were scheduled to undergo US-guided breast biopsy and were capable of comprehending the nature of the study. They each had a suspicious palpable or nonpalpable solid or complex (cystic and solid) lesion that was identified at US. In addition, they were willing and able to return for required follow-up visits at 1, 7, and 30 days.

Patients were excluded from the study if they had undergone a previous biopsy in the same location in the breast scheduled for US-guided biopsy or if they had a simple cyst in the area to be sampled at biopsy. Also excluded were patients who had contraindications to the electrosurgical procedure (eg, the presence of a cardiac pacemaker), were participating in any other clinical trial of an investigational drug or device, had an implant in the breast scheduled for biopsy, or had a concurrent breast infection.

The three principal investigators (N.D., S.H.P., A.J.K.) independently reviewed the mammograms of the patients enrolled at their respective sites. They categorized breast composition on the basis of findings in the prebiopsy mammogram, and they performed either US or repeat mammography to identify lesion type and size. Breast composition was categorized with one of four standardized descriptors on the study case report forms: almost entirely fat, scattered fibroglandular densities, heterogeneously dense, or extremely dense. Pathologic results were used to categorize target lesions as benign or malignant.

Data Analysis
Device effectiveness.—When a target lesion was sampled at biopsy and the histologic diagnosis was made, the procedure was considered a success. The presence or absence of any biopsy-introduced artifact was also reported, as was the type of artifact and whether or not it adversely affected the pathologist’s ability to obtain a histologic diagnosis. The investigators noted any discrepancy between the imaging and pathologic findings. The pathologists determined the weight and sufficiency of the specimen for the purposes of diagnosis. They rated the quality of the specimen as very good, good, average, poor, or inadequate on the basis of specimen composition of all tissue, mostly tissue, half tissue and half blood, mostly blood, or all blood, respectively.

Ease of procedure.—The investigators compared the pathologist’s ability to obtain a satisfactory histologic diagnosis, ease of tissue and lesion penetration, and pain. They also scored the ease of penetration and ease of handling with a five-point scale: 1 = very easy, 2 = easy, 3 = somewhat difficult, 4 = difficult, or 5 = extremely difficult.

Time of procedure.—The average time required to perform the biopsy (ie, time from penetration of device under skin to withdrawal of device from breast) was measured.

Patient comfort and complications.—The patients were followed up at 1, 7, and 30 days after the biopsy procedure to evaluate wound healing and any complications, such as swelling, hematoma, infection, and pain. Pain assessments immediately after the biopsy procedure and those at 1, 7, and 30 days after the procedure were recorded by the patient by using a visual analog scale that ranged from 0 to 10. Patients were asked to place a mark on a 10-cm-long horizontal line at a point that best represented their perceived level of pain. The leftmost end of the line (score of 0) was identified as "no pain," and the rightmost end of the line (score of 10) was identified as "most severe pain." The marks made by the patient were measured (in centimeters to one decimal place) from the left end of the line and rounded up to the nearest whole centimeter for values of 0.5 cm or more.

Patients were removed from the study if they had completed all examinations by 30 days after the original biopsy procedure or if a definitive surgical procedure (eg, lumpectomy or mastectomy) was indicated following the core biopsy procedure. If a definitive surgical procedure was indicated, final evaluations of the success and safety of the biopsy procedure were made prior to surgery. Patients could be removed from the study at the discretion of the investigator only if continued participation in the trial would in some way jeopardize the patient’s health or welfare.

Statistical analysis.—The Fisher exact test was used to assess differences in the pathologist’s ability to obtain a histologic diagnosis. It was also used to compare differences in ease of device penetration. The Student t test was used to evaluate differences in biopsy procedure time and patient pain assessments. A P value of .05 or less was considered to indicate a statistically significant difference.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
DISCUSSION
 REFERENCES
 
Forty-nine patients (mean age, 50 years; range, 29–65 years) were randomly assigned to the treatment group. Fifty patients were randomly assigned to the control group (mean age, 52 years; range, 27–79 years). Breast composition was comparable between groups, as were lesion characteristics (Tables 1, 2). There were no statistically significant differences in age or breast composition between groups.


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  		TABLE 1. Breast Composition

 

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  		TABLE 2. Lesion Characteristics

 
Device Effectiveness
A histologic diagnosis was obtained in 98% (48 of 49) of the treatment patients and 100% (50 of 50) of the control patients. There were no significant differences between the groups (P = .49, Fisher exact test). Treatment group results were clinically acceptable and equivalent to control group results on the basis of the pathologist’s ability to obtain a histologic diagnosis. The quality of the specimen was rated as good or very good in 98% of treatment group patients and 100% of control group patients. In one treatment patient, the specimen quality was inadequate; however, this was the same patient for whom the pathologic findings and imaging findings were discordant. In this patient, histologic diagnosis was possible, but the pathologic findings (ie, benign) and imaging findings (ie, Breast Imaging Reporting and Data System, or BI-RADS, category 5) were discordant. On the basis of the physician standard of care, surgical breast biopsy was performed, and the imaging findings were confirmed. For purposes of analysis, this was reported as a failed histologic diagnosis.

The pathologists reported no RF-related biopsy artifacts in the treatment group. Biopsy artifact was noted in one treatment patient and one control patient. A small amount of blood was noted in the treatment patient, and focal compression (ie, an artifact produced by inadvertent crushing of the tissue during processing) was noted in the control patient. A successful histologic diagnosis was possible for both patients.

Ease of Procedure
Tissue retrieval proceeded uneventfully in both groups, except in one control patient in whom the biopsy system probe malfunctioned and had to be replaced before completion of the biopsy procedure.

On the basis of the five-point scale, the RF introducer provided easier penetration in both groups (treatment group mean score, 1.6; control group mean score, 2.4), particularly in patients with dense breasts (treatment mean score, 1.0; control mean score, 2.9). Placement of the RF introducer (Fig 2) was scored as easy or very easy in 82% (38 of 46) of treatment patients compared with only 47% (23 of 49) of control patients in whom placement of the handheld breast biopsy system alone was scored as easy or very easy (Table 3). In patients with fatty or fibroglandular breast composition, investigators reported breast penetration as very easy or easy in 79% (19 of 24) of treatment patients and 65% (15 of 23) of control patients. In patients with dense breasts, investigators reported breast penetration as very easy or easy in 90% (19 of 21) of treatment patients and 32% (eight of 25) of control patients. No significant difference in ease of penetration with the RF introducer was noted between groups for fatty or fibroglandular breast composition (P = .25). A significant improvement in ease of penetration with the RF introducer was seen in patients with dense breasts compared with that in patients with dense breasts in whom only the handheld breast biopsy system was used (P < .001). These results are summarized in Figures 3 and 4.



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  		Figure 2. US image (longitudinal, antiradial plane) obtained just before biopsy shows probe (small arrow) of handheld breast biopsy system inside cannula (large arrow) of RF introducer.

 

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  		TABLE 3. Ease of Penetration

 


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  		Figure 3. Ease of penetration for fatty or fibroglandular breast composition (P = .25).

 


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  		Figure 4. Ease of penetration for dense breast composition (P < .001).

 
The RF introducer was light compared with the weight of the handheld breast biopsy system. Moreover, placement of the cannula of the RF introducer obviated holding the system probe in position. This contributed to greater operator freedom of movement.

Procedure Time
Average times of biopsy procedures for the treatment and control groups were 9.1 and 8.7 minutes, respectively. The difference was not significant (P = .63).

Patient Comfort and Complications
There were no significant differences in patient pain level at any of the evaluation intervals, as demonstrated in Table 4. Moreover, the mean pain levels for both groups at each interval were less than 3 cm from 0. If one were to classify a 0–10 numeric pain scale in terms of mild, moderate, and severe pain, all of the mean pain levels for both the treatment and control groups would be mild. Results in the treatment group were clinically acceptable and equivalent to those in the control group.


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  		TABLE 4. Patient Pain Assessment by Evaluation Interval

 
Clinical complications observed during the study were of a type and incidence that are typically associated with those observed during percutaneous needle core biopsy. Reported complications are summarized in Table 5.


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  		TABLE 5. Clinical Complications: Total for All Evaluation Intervals

 
Bleeding, the most common complication, occurred during the procedure in one treatment patient and after the procedure, as hematomas, in three control patients. All bleeding events resolved spontaneously. Skin defects were noted in two treatment patients and occurred at a rate comparable to rates reported in the literature during use of the handheld breast biopsy system alone (1,2). In both of these patients, the lesion locations necessitated insertion of the RF introducer at a very inferior angle to traverse the breast tissue very close to the underside of the skin margin. The skin was inadvertently cut in both patients. Neither patient required treatment, and both skin defects resolved uneventfully. One treatment patient reported feeling the sensation of a muscle twinge. Complications reported for the treatment group were clinically acceptable and equivalent to those reported for the control group.


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
REFERENCES
 
The RF introducer is designed to be small, light, and easy to hold during initial penetration through breast tissue without the bulk and heaviness of current percutaneous biopsy devices. The introducer is also designed to be a coaxial guide through which a biopsy device may be inserted or reinserted once penetration of breast tissue to the target lesion is accomplished. It is intended for use in conjunction with existing devices for US-guided diagnostic breast biopsy procedures. It is not intended for complete removal of suspicious lesions.

Results of this study demonstrate that the RF introducer met the design performance objectives. The investigators easily grasped the key operational steps. Investigator success in penetration of breast tissue and advancement to the target lesion was comparable with the RF introducer and the handheld breast biopsy system and with the handheld system alone.

These data clearly demonstrate that use of the RF introducer did not adversely affect tissue acquisition with the hand-held breast biopsy system. No difficulty was encountered during tissue sampling with the probe of the handheld system in the cannula of the RF introducer. No RF-induced biopsy artifacts were reported, and the pathologist’s ability to obtain a histologic diagnosis was comparable to that with the handheld system alone.

With US guidance, breast biopsy can sometimes be a challenging task, especially when the radiologist encounters resistance from breast tissue. This resistance can be related to the type of breast parenchyma and to the lesion itself or its position (eg, close to the nipple area). Various methods have been used to create a path for the biopsy needle. Anesthetics can be injected to allow dissection of the tissues. Acquisition of core specimens is another way to create a tunnel to place the biopsy needle in a good position. However, these methods can take extra time or may be traumatic for the patient.

In our study, the RF introducer did not significantly prolong the mean biopsy time or result in increased patient pain or complications.

Average procedure time was the same for both groups, regardless of breast parenchyma type. The time to remove the obturator from the cannula and insert the probe of the handheld breast biopsy system had no direct effect on the patient. Elimination of the need to constantly hold the probe of the handheld system in position made the procedure less tiring for the radiologist. The RF introducer is lightweight and easy to hold; these features also contribute to radiologist comfort during the biopsy procedure.

No pain related to the RF introducer was demonstrated. The fact that the procedure seemed to be initially more comfortable for the patient may be related to the ease of penetration and to the pure-cutting mode. Tissues are less traumatized and therefore less painful during recovery.

As reported in the literature and according to our experience, dense breast tissue may prevent advancement of the probe of the handheld breast biopsy system to the lesion (8). The RF introducer provided significantly easier penetration of breast parenchyma, particularly in patients with dense breasts. This result is important for such patients because many of them may not be candidates for stereotactic breast biopsy. In our practice, approximately 10%–20% of patients have very dense breast tissue composition identified either at imaging or during anesthetic injection. In these patients, US-guided breast biopsy is easier with the RF introducer, and the quality of the biopsy procedure is improved. The added cost of using the RF introducer with the handheld system is minimal compared with the cost of breast biopsy with the system alone.

No device failures or malfunctions were reported in this patient cohort.

In conclusion, our initial results suggest that the RF introducer may serve as a useful adjunct to the handheld breast biopsy system by facilitating the penetration of breast tissue without causing any deleterious effects in the biopsy specimen.


   ACKNOWLEDGMENTS
 
The authors thank Michèle Roy, MD, FRCP(C), from Hôpital du Saint-Sacrement; Dean F. Melville, MD, from Community General Hospital; and Terese I. Kaske, MD, Mark A. Dennis, MD, Richard G. Obregon, MD, from the Sally Jobe Breast Center for contributing to the breast biopsy procedures in this study.


   FOOTNOTES
 
N.D. and S.H.P. are shareholders of SenoRx.

Abbreviation: RF = radiofrequency

Author contributions: Guarantors of integrity of entire study, all authors; study concepts and design, all authors; literature research, M.L.M.; clinical studies, N.D., S.H.P., A.J.K.; data acquisition and analysis/interpretation, all authors; statistical analysis, M.L.M.; manuscript preparation, N.D., M.L.M.; manuscript revision/review, all authors; manuscript definition of intellectual content, editing, and final version approval, N.D.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 

  1. Glover JL, Bendick PJ, Link WJ. The use of thermal knives in surgery: electrosurgery, lasers, plasma scalpel. Curr Probl Surg 1978; 15:1-78.
  2. Anderson J. Surgical diathermy in breast cancer: the application of the arc electrode or cutting current to the radical operation. Br J Surg 1928; 15:500-513.[CrossRef]
  3. O’Connor JL, Bloom DA, William T. Bovie and electrosurgery. Surgery 1996; 119:390-396.[CrossRef][Medline]
  4. Miller E, Paull DE, Morrissey K, Cortese A, Nowak E. Scalpel versus electrocautery in modified radical mastectomy. Am Surg 1988; 54:284-286.[Medline]
  5. Sheen-Chen SM, Chou FF. A comparison between scalpel and electrocautery in modified radical mastectomy. Eur J Surg 1993; 159:457-459.[Medline]
  6. Parker SH, Klaus AJ, McWey PJ, et al. Sonographically guided directional vacuum-assisted breast biopsy using a handheld device. AJR Am J Roentgenol 2001; 177:405-408.[Abstract/Free Full Text]
  7. Duchesne N, Coté G, Dorion A, Roy M. Ultrasound-guided Mammotome breast biopsies (abstr). AJR Am J Roentgenol 2001; 176(suppl):7.
  8. Simon JR, Kalbhen CL, Cooper RA, Flisak ME. Accuracy and complication rates of US-guided vacuum-assisted core breast biopsy: initial results. Radiology 2000; 215:694-697.[Abstract/Free Full Text]




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