Technology and industry editor, Kathleen Dallessio, writes about the new advances in MR imaging of the breast.
Kathleen M. Dallessio
Although most imaging studies and biopsies of the breast are
conducted using mammography or ultrasound, in some cases, magnetic
resonance (MR) imaging may be the most appropriate modality.
"There are a number of indications for breast MRI," said Steven
E. Harms, MD, FACR, Professor of Radiology, University of Arkansas
for Medical Sciences, Little Rock, AR in an interview with
. Dr. Harms is also the Medical Director at
Aurora Imaging Technology, Inc.
, North Andover, MA. "Probably the most common use is in a patient
with an inconclusive clinical or diagnostic imaging study. Getting
question marks on imaging exams is not unusual--approximately 10%
of mammograms require some other kind of test--and breast MRI is
the 'high court' of breast imaging. It's very similar to having an
abnormal chest X-ray and being able to get a chest computed
tomography (CT). Breast MRI is the back-up procedure for all other
breast imaging procedures; it's at the top of the food chain."
Breast MRI can be especially helpful in women who have impaired
mammography results due to dense breast tissue. It can also be used
to detect occult primary breast cancer in patients presenting with
metastatic disease without a known primary tumor. "Other
indications," noted Harms, "include any patient with a high
suspicion of cancer who is a breast-conservation candidate. You can
determine the presence of additional disease. You can determine the
extent of the disease for more appropriate therapy. In patients who
have had a lumpectomy with positive margins, MR can evaluate for
the presence of additional disease, which will help to determine
whether to do a lumpectomy or a mastectomy."
MR can also be used to monitor cancer therapy. "We can evaluate
adjuvant therapy or chemotherapy to determine if there is a
response to chemotherapy or the extent of residual disease in the
breast of patients who might be candidates for breast conservation
after chemotherapy," said Harms.
This imaging modality is also very useful for women with
silicone breast implants, since MR studies are not impaired by the
presence of silicone injections or implants as are mammography and
ultrasound. "In women with silicone implants," added Harms, "we can
not only find the cancer but also determine if the implants are
intact or if there is free silicone in the breast."
In addition to finding cancer, MR imaging can also be used to
exclude the presence of breast cancer in women who are determined
to be at high-risk due to family history, genetic markers, or
high-risk histology. "For example," said Harms, "if a patient has a
cancer on one side, the other side needs to be evaluated to make
sure there's not a cancer on the other side. Even if all the other
imaging studies are negative, MRI can pick up additional
One major drawback, however, noted Harms, has been that once the
lesion is found using MR imaging, the physician still had to rely
on ultrasound for localization and biopsy. "One of the reasons we
do breast MRI is that we can see tumors that you can't see any
other way; they can't be seen with mammography or ultrasound.
Obviously if MR reveals disease that can't be seen any other way,
then you can't rely on those other methods to do the biopsy," he
explained. "As part of providing a breast MRI service, we have to
be able to perform biopsies and localization. We don't want to have
an abnormal MRI suspicious for cancer and then have to tell the
patient, 'We don't have any way of getting a tissue diagnosis.'
That is a terrible position to be put in and that is the reason why
I believe that breast intervention should be an integral part of
providing breast MRI services."
To address this need, Aurora Imaging Technology has designed
their Dedicated Breast Magnetic Resonance Imaging System with the
newly approved Integrated Interventional System.
"Instead of building a machine to make breast images, with
breast biopsy considered after the fact," said Harms, "our machine
is built from the ground up with intervention in mind. What that
means is that all of the imaging features of the machine--the
magnetic field, the gradient, the patient table--are also designed
for better intervention."
The imaging system, which has been on the market for several
months, was recently upgraded to a gradient of 21 mT/m at 40 msec
rise time. "This is fast enough to do dynamic scanning and yet
still very linear," said Richard W. Rosene, vice president of sales
at Aurora. The magnet is also being upgraded from 0.5 to 1.5 Tesla.
The patient table acts as an incline plane. "All the coils are
built up and around the breast," said Rosene.
Harms noted, "Our gradients are designed to be low-distortion
gradients--the lowest distortion gradients in the business, with
<1 mm of error over 44 cm, where the typical whole-body scan
will have 2 to 4 cm of error. So it's a significant improvement in
the linearity of the gradient. It is designed so that if you find
an area of abnormality on the breast, you can accurately guide a
needle into it and you won't be fighting distortion errors on the
The Interventional System (which was approved by the FDA in
February for the localization, biopsy, and treatment of lesions
visualized on MR images) is an extension to the patient table that
attaches to the side. The extension, which can slide back and forth
along the table, includes 2 mylar grids for each breast and a
staging device that can be placed in any one of four quadrants. LED
readout is used to locate lesions stereotactically to within 3
"The latest attachment, which is the interventional attachment,
is simply the final piece that makes intervention possible with
this machine. Instead of using regular compression plates as are
used in mammography or even biopsy systems for mammography, these
plates are designed to fix the skin of the breast so that there
will be minimal movement in the breast tissue when you do the
intervention," said Harms.
"One of the problems that add-on biopsy systems for whole-body
MR systems have is that you don't have good access to the breast;
you are usually working through a small hole, and not all the
breast tissue can be biopsied," he continued. "The tissue near the
chest wall is particularly difficult to biopsy with a whole-body
system. Our system has a very open architecture because the whole
table is designed for breast intervention. You've got lots of room
to work, and you can approach the breast from the medial or the
lateral side. Most add-on systems approach the breast only from the
lateral side; ours can approach from the medial too."
"This is a relatively automated system," continued Harms. "With
the workstation included, you put a cursor on the lesion and then
mark the position where the lesion is and then mark the position of
a fiducial marker on the stage that holds the needle. Then the scan
console displays automatically calculated numbers that allow you to
put the needle in place accurately."
"An additional highlight of the machine's interventional design
is that the scan console is in the room so that the technologist
who runs the scanner doesn't have to go outside the room to operate
it," he said. "The scan console is right next to the interventional
table, and you can see the images as you do the biopsy. You can run
the scanner without ever having to leave the room."
One drawback to breast MR imaging is the lack of reimbursement
for most examinations. "There are some new areas that are not yet
readily reimbursed," said Harms. "The most visible one is high-risk
patients, people who have a high genetic risk for breast cancer.
Right now they do not have a suitable alternative: many of them are
recommended to have prophylactic mastectomy. Another group that
could benefit from breast MRI but are also not readily reimbursed
is people with very dense breast tissue. They are not very well
imaged by mammography and often undergo numerous additional tests
because of the ambiguity of mammograms. Breast MRI has no problem
imaging dense breasts and could be a suitable alternative. In fact,
in Boston, Faulkner Hospital is conducting a study of women with
dense breasts who could be scanned and pay out of pocket if they
want to. So I think that the availability of a dedicated breast MRI
that could do low-cost breast MRI procedures is a real benefit for
those people because it offers them an alternative. But it's not
readily reimbursed, so they have to pay out of pocket. Frankly,
it's not likely to be very successful until we can get third-party
"The biggest difference in this device compared with what's out
there is that the whole system is built from the ground up around
intervention," concluded Harms. "It's not an afterthought add-on
piece. As a result, this design will translate into clinical
benefits of being able to do the biopsy faster, more easily, and
Other breast MRI news
Suros Surgical Systems
(Indianapolis, IN) recently previewed a new MRI-compatible version
of its Automated Tissue Excision and Collection (ATEC) breast
biopsy and excision system. The vacuum-assisted system can now be
used with ultrasound, stereotactic systems, and MRI. It is capable
of performing 16 biopsies per minute with either a 9- or 12-gauge
disposable needle. The company has planned a full launch of the new
system for the end of the first quarter of 2003.
(Wauskesha, WI) recently introduced a new open breast array coil
for use on the Intera 1.5 MRI scanner from P
hilips Medical Systems
(Andover, MA). The coil has a four-channel design to image in
either a unilateral or bilateral mode and an open design for ease
of patient positioning and for use in biopsy or needle