BSGI: One More Option in the Diagnosis Arsenal
We recently spoke with Dr. Susan K. Boolbol, an Alliance Medical Advisory Board member and Chief of Breast Surgery at Beth Israel Medical Center, to ask about advances in breast imaging techniques and a particular tool being tested at Beth Israel called Breast Specific Gamma Imaging, or BSGI.
 Dr. Susan K. Boolbol |
Q: Are tools other than mammograms better at detecting breast cancer?
A: Mammography is generally accepted as the gold standard for breast cancer
screening. But mammography isn't perfect - it misses as many of 15 percent of
breast cancers, and in cases where breast cancer is found, other tools are often
used to provide additional data about the cancer. Many people are familiar with
some of the diagnostic tools already in use, including MRI and ultrasound testing,
but new tools are being developed, each with specific benefits. One of those is
BSGI.
Q: What does BSGI do differently than mammograms or other imaging tools?
A: Unlike a mammogram or ultrasound, which offer static pictures of a specific point
in time, BSGI (like MRI) is a functional imaging test, meaning that it provides a
view of how cells and tissue work in the body.
Q: How exactly does BSGI work?
A: In a BSGI test, a substance called sestamibi is injected and absorbed by the breast
cells. Normal cells absorb sestamibi at one rate, but cancer cells work "faster"
than normal cells and absorb it at a quicker rate, allowing the image reader to
discern a difference. We see a darker area - a hot spot - and we can tell that
something abnormal is going on in that spot.
Q: How is Beth Israel Medical Center testing BSGI?
A: Beth Israel is now involved in a comparison study of BSGI and MRI, which is
frequently used for additional imaging of the breast but can be unsuitable for
some patients. The goal is to complete a prospective study of 100 patients who
receive both tests to determine exactly how BSGI results compare to those of
MRI. BSGI has several seeming advantages. One plus has to do with patient
comfort - there is no claustrophobic tube because the patient sits in a chair.
Previous studies also observe that BSGI results in a lower false positive rate than
MRI, which means fewer benign biopsies. We expect to see that the two tests
have similar detection rates, but if we discover that BSGI can find the cancer
without the false positives, it will give us an added comfort level.
Another Beth Israel study found that among women newly diagnosed with breast
cancer, BSGI identified additional breast cancer lesions in nine percent of
the women - cancer in another location that didn't show up on a mammogram.
That's important because some patients have recurrences quite quickly. We know
that those cancers didn't develop overnight, but they weren't caught with the initial
screening. If we have an additional tool, we can make sure we are getting all the
cancer when we perform the initial surgery.
Q: Is BSGI covered by insurance?
A: It is not yet covered by most insurance. We hope that will change over time as
more evidence of its efficacy emerges. More and more hospitals have this
technology - Beth Israel is one of three in New York City alone - and the test is
very active internationally.
Q: Is BSGI a replacement for mammography?
A: No. BSGI is a promising diagnostic tool but not currently a good screening tool
because of expense and availability. We use BSGI in women who are already
diagnosed. We compare it with results of the mammogram to see if there are any
abnormal areas the mammogram didn't pick up. No one of these tests is likely to
replace another - they all have advantages and disadvantages depending on the
patient. We need more than one test to accommodate all the nuances.
