Ultrasound Breast Biopsy
ULTRASOUND MAKES GREAT STRIDES IN EVALUATING BREAST LESIONS
BY LORI FINK
Kathryn has just received her most feared diagnosis–suspicious mass. Although her physician believes the lump is most likely benign, Kathryn has a choice to make: Does she return for a follow-up examination in 6 months or undergo an ultrasound core biopsy to assess the mass?
With current ultrasound advances, more women are turning to this modality to assess suspicious masses or densities. Deemed a quick, easy and cost-effective procedure, ultrasound-guided breast biopsy is rapidly becoming a common procedure that increases accessibility to a lesion, and is an acceptable alternative to surgical excision.
“In our institution, better than 85 percent of all breast biopsies are being done by ultrasound. Why? It is faster, easier for both us and the patients, uses no radiation and we can place the needle just as accurately with ultrasound,” says Peter J. Dempsey, MD, professor of radiology and section head of breast imaging at the University of Alabama Medical Center in Birmingham.
Each year, nearly 700,000 women undergo surgical breast biopsy for suspected breast cancer; however, for 80 percent of these women, no cancer is found.1 Ultrasound, hailed as a tool that may eliminate the need for most women to have an unnecessary surgical excision, also offers the assurance that women will receive an accurate evaluation of their suspicious mass or lesion.
In an abnormal screening mammogram women are commonly diagnosed with one of three problems: calcifications, a non-palpable mass or density, or a lump felt by the woman that is either seen or not evident on a mammogram. Women with small suspicious breast lesions that are visible on ultrasound are candidates for sonographic-guided breast biopsy. Evaluation by ultrasound assures in nearly 95 percent of cases that masses or densities are seen by the radiologist.
TYPES OF ULTRASOUND BIOPSIES
Ultrasound provides physicians with information in an easy and accurate manner. Through this modality, they can determine the presence of a lump, its location and if a lump is actually a cyst. In some situations ultrasound is not needed, such as in women with palpable lumps measuring one inch or more. “A surgeon commonly evaluates a lump of that size without ultrasound and may perform an in-office procedure known as fine-needle aspiration (FNA). During this procedure, a sample of cells, not tissue, is drawn from the lump. Research shows that the results are not as conclusive as with core biopsies,” indicates Mark Segel, MD, director of breast imaging for the Karmanos Cancer Institute-Wayne State Medical School in Detroit, in a pamphlet he provides to his patients.
Over the past several years surgeons have used FNA extensively as a means to establish a cytological diagnosis for suspicious breast masses. Most surgeons use this technique for palpable breast masses, however, it can also be used for suspicious mammographic lesions. Differing in technique, core needle biopsy is used to guide a special biopsy needle to the lesion so that a histological sample can be obtained without surgery.
While both procedures can be performed using either ultrasound or stereotactic guidance, the needle size differs. FNA is typically performed with a 20 gauge needle or smaller, while core biopsy uses either an 11 or 14 gauge needle, says Valerie P. Jackson, MD, John A. Campbell professor of radiology and chief of breast imaging, Indiana University School of Medicine in Indianapolis.
US BIOPSY TECHNIQUE
The technique used for performing an ultrasound-guided breast biopsy is a personal preference to the people performing the procedure. While some prefer using both hands, others rely on other methods.
Two commonly used techniques for targeting lesions using ultrasound guidance are needle guides and the freehand method. Use of needle guides maintain the alignment of the needle and the transducer. The major limitation with this technique is that the person performing the ultrasound is restricted to a single angle of approach, which may not be convenient for all lesions. The freehand technique allows the operator a great deal of flexibility in the approach to the lesion. Here the transducer is typically held in the non-dominant hand while the needle is grasped in the dominant hand. Depending on the location of the lesion, however, this setup may be reversed. This technique allows unlimited angles of approach, but can be reduced to three, according to a paper authored by Handel Reynolds, MD, associate professor of radiology, Indiana University School of Medicine. These approaches are the oblique, where the needle pierces the skin adjacent to the short end of the transducer and is advanced toward the lesion along the plane of the ultrasound beam; the horizontal, where the skin is pierced in a location so that the needle can be advanced into it using a horizontal path; and the vertical needle approach, which involves targeting the lesion from the side rather than the end of the transducer.
How exactly does ultrasound core biopsy work? “You are scanning to look if there is a solid hypoechoic mass and to explain the palpable lump or mammographic mass,” says Dr. Segel, whose institution has performed nearly 500 ultrasound-guided biopsies since 1993. “If you find a solid hypoechoic mass, you can then characterize it by looking at the margins and its shape.” Dr. Segel references criteria developed by A. Thomas Stravos, MD, in Denver, designed for looking at masses by ultrasound that characterize risk factors if the mass is suspicious or looks benign. ATL’s New Breast Ultrasound Procedure clinical application, when used as an adjunct to mammography and physical examination, may reduce the number of breast biopsies performed by more than 40 percent.
After viewing a solid hypoechoic mass by ultrasound, the lesion can be deemed either suspicious, probably benign or normal. If the lesion is marked as suspicious, a biopsy will most likely be performed. If the lesion is believed to probably be benign, however, a woman is offered the option of either having an ultrasound biopsy or return in 6 months for a follow-up examination.
The procedure is relatively quick, requiring only about 20 minutes preparation time and an additional 20 minutes for the biopsy itself. “If a woman chooses ultrasound-guided biopsy, we then isolate the lesion and turn the patient in position so that the mass is looking straight up at the ceiling,” offers Dr. Segel, as he details the way he performs a biopsy. Under ultrasound guidance, the breast is then numbed with lidocaine, a skin nick is placed, the needle is inserted into position, and the tissue is removed.
A rule that Dr. Segel says is essential for evaluating the success of a biopsy is “sinkers are good, floaters are bad.” After the tissue is placed in a formalin bottle, it will either sink or float to the top. “Solid tissue from a fibroabnoma or cancer sinks to the bottom, but if you miss the lesion and hit fat it will float to the top,” he indicates. “If you correctly do the biopsy, you are done after four samples sink to the bottom. It usually takes about five times to get four sinkers.”
The final steps in the biopsy procedure include bandaging the area and applying an ice pack and compression.
Two questions often arise in regard to ultrasound-guided breast biopsy: Do you scan the entire breast or do you target just the area? “We tend to scan the entire breast because we have found a few breast cancers by scanning the entire breast and it is not uncommon to find, such as if someone has one fibroadenoma on a mammogram, other similar fibroadenomas,” Dr. Segel says. He indicates that he has also found some other incidental cancers while scanning the entire breast.
Many physicians would agree–ultrasound-guided breast biopsy is an easy and accurate procedure for patients. “We believe, if you talk about masses or lumps, that virtually in more than 90 percent of cases ultrasound-core biopsy can eliminate the need for surgical biopsy,” shares Dr. Segel. “It is a minimally invasive procedure with no surgery required, the healing time is minimal, causes no scarring, and is one-third the cost of surgery.”
Other systems that provide these results include the Sonopsy by the United States Surgical Corp. (Norwalk, Conn.), which uses automated 3-D ultrasound imaging to locate a suspicious lesion, real-time ultrasound to track the progress of the biopsy needle, and 3-D ultrasound verification to help confirm accurate positioning of the needle. Another system is the UltraGuide™ 1000 from UltraGuide Ltd. (Israel).
Cost is a key factor in selecting ultrasound over surgical biopsy procedures. Eliminating the high costs of operating rooms, anesthesia and recovery room expenses, ultrasound dramatically reduces costs to patients. “There are clearly huge cost savings,” indicates Dianne Georgian-Smith, MD, director of breast imaging at the University of Washington Medical Center in Seattle. “While surgery can be several thousands of dollars, ultrasound costs just a few hundred dollars.”
Another added benefit that ultrasound-guided breast biopsy provides to women is its superior cosmetic results. “Cosmetically this technique is fabulous. You just don’t have any problems with it and women heal very nicely,” Dr. Dempsey states.
In addition to offering rapid healing and more comfortable positioning to patients, little or no risk factors or complications are typically associated with this procedure. With the exception of bruising and the slight risk of bleeding, few risk factors are attached to ultrasound-guided biopsy. “This is a very safe thing,” shares Dr. Dempsey, who indicates that there were no complications in the first 400 core biopsies that were performed at his institution. “There is a safe way to do it and we are working to train people to do it that way. Mistakes can occur if someone is not properly trained, but a lot of people are now getting involved with organizing strict training courses to cover all aspects of this so that individuals receive proper training.”
ULTRASOUND VS. STEREOTACTIC BIOPSY
In many practices in the United States where both ultrasound and stereotactic equipment are available, nearly 60 percent of needle biopsies are performed with ultrasound guidance, while only 40 percent use stereotactic equipment. For lesions suitable for both ultrasound and stereotactic guidance, the choice of which modality to use lies chiefly on the expertise of the radiologist and the equipment he or she has available.
Ultrasound has been found to be faster than stereotactic guidance because the needle position is visualized in real-time throughout the procedure. “It’s the difference similar to looking at slides or at a movie,” Dr. Georgian-Smith indicates. “Ultrasound offers something similar to a movie of real-time imaging where you can actually see the needle and where things are seen as they are happening, as opposed to taking a still image (as in stereotactic procedures).”
While ultrasound core biopsy is designed primarily to assess palpable masses and masses that can be seen on a mammogram and not yet felt, it is not helpful in examining calcifications. For this purpose, women turn to stereotactic biopsy to assess suspicious calcifications. These procedures are performed on a modified mammogram machine, with either the patient sitting up or, most commonly, in the prone position with the breast suspended through a hole and then compressed so that X-ray can be taken to see the lesion. “It works by taking two pictures of the area at different angles to one another, getting stereotactic views of it,” indicates Dr. Georgian-Smith. “The computer can then use those views to determine the depths of where to go.”
Ultrasound has been found to be an effective and time-saving modality to use as an imaging guide for 14 gauge core needle biopsies using a biopsy “gun.” Non-palpable lesions can be easily biopsied under ultrasound guidance and can be successful when the stereotactic X-ray device has failed because of anatomical constraints, such as small breasts or lesions near the chest wall. A linear transducer is preferred for this task as it enables the radiologist to see the long axis of the needle as it approaches the margin of the lesion, she indicates.
Another advantage of using ultrasound over stereotactic procedures is the elimination of radiation. Stereotaxis involves X-ray images of the suspicious lesion, producing radiation for the patient. Because no X-rays are needed with ultrasound, radiation is totally eliminated from this procedure.
One of its limitations, however, involves the technique for performing this type of biopsy. Similar to stereotactic guidance, ultrasound guidance biopsies require hand-eye coordination. “It takes more operator dependence,” indicates Dr. Georgian-Smith. “It’s like learning to play Nintendo. You have a joystick in both hands, are looking at the screen and are trying to coordinate everything. The first time you do it you don’t go very far. It takes a lot of operator dependence to do these procedures.” The development of commercially available synthetic and man-made phantoms have helped remedy this limitation. These phantoms allow radiologists to practice the techniques of ultrasound-guided needle biopsy.
One of the notable problems with using ultrasound guidance is that it cannot be used to guide biopsy for lesions that are not sonographically visible, such as clustered microcalifications with an associated mass and some small solid masses that cannot be targeted. Stereotactic localization for needle biopsy is required for these lesions.
Some radiologists today continue to perform biopsies through a stereotactic method instead of relying on ultrasound, however, use of ultrasound reaps additional benefits to both patients and to those performing a biopsy. “If you know how to use ultrasound, it is quicker and cheaper than stereotactic biopsy,” states Dr. Segel, who believes that it is a more user- and patient-friendly modality. “We tend to do anything that can be done by ultrasound through ultrasound.”
A FUTURE STANDARDIZED PRACTICE?
As more radiologists are learning how to perform ultrasound-guided breast biopsies, there is the possibility for these procedures to become more standardized in the near future. “I see it as a staple and fundamental procedure of knowing what to do to evaluate breast masses,” indicates Dr. Georgian-Smith. “It could be synonymous to stereotactic biopsies; some kind of needle sampling by the radiologists that has become an essential step or procedure that they need to know to evaluate breast masses.”
1. “Use of ultrasound may eliminate surgical breast biopsy for many women,” Harper Hospital/Wayne State University, 1997.
2. Handel, ER. “Ultrasound Guided Breast Intervention,” Society of Breast Imaging 3rd Postgraduate Course Syllabus, 1997.
3. Jackson VP. “Ultrasound guidance for needle biopsies,” 17th Annual Breast Imaging Conference, 1997.
Lori Fink is an associate editor at ADVANCE.