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What is MRI and how is the procedure done?
Magnetic
resonance imaging (MRI) is a method of medical imaging in which the
patient’s area of interest is viewed in extremely thin segments from
multiple directions, providing computer-generated images. The
radiologist can then “page through” the tissue or create a
three-dimensional image. No radiation is involved, and there is no
flattening or compression of the breast in this 30 to 40 minute
procedure. The patient lies face-down on a special table so the breasts
can hang through an opening into a special “coil” that transmits and
receives the radio frequency signals that are used in MRI. Once
positioned, the patient is moved feet first into the magnet so she can
still look to the outside. Our breast- dedicated MRI has the largest
opening available to alleviate any feelings of claustrophobia. Earplugs
are provided to diminish any sound of the MRI. An IV line is established
beforehand to allow injection of the gadolinium contrast, which may burn
slightly with administration. The most common side effect of gadolinium
is headache or nausea. A true allergy is extremely rare (gadolinium is
not a typical “dye” as used in so many radiologic procedures, but is
actually a metallic element).
For patients with moderate or severe renal (kidney)
failure, a serious condition called Nephrogenic Systemic Fibrosis can
occur in a small percentage after the administration of gadolinium. If
you have been diagnosed with kidney failure, you should consider
alternatives to MRI. If you are unsure of your status, a screening test
for kidney failure will be recommended.
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Why is the gadolinium necessary?
Breast cancers have
a rich blood supply, so tumors “light up” on MRI, helping to distinguish
them from normal breast tissue. These are called areas of “enhancement.”
It is the contrast agent (gadolinium) that makes breast MRI so much more
sensitive in cancer detection than mammography.
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If there is no enhancement, am I cancer free?
The
power of breast MRI is indeed its “Negative Predictive Value.” If there
is no enhancement, then the chances of breast cancer are extremely low.
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What about false positives?
As with mammography and
ultrasound, there are false positives with breast MRI. With mammography,
even after decades of improvements, only one in five biopsis generated
will prove to be cancer, leaving four "false positives." MRI is slightly
better in this regard, but false positives still occur due to benign
tumors and other conditions of the breast. The most likely time to
experience a false-positive is the baseline exam as there will be no
previous study for comparison. Also, false-positives are more common in
premenopausal cycle to reduce the chance of a false alarm on MRI. For
postmenopausal women, there is no special timing, but it might help to
stop hormone replacement therapy for several weeks prior to your study.
After having an MRI, if you receive a phone call
stating that we have seen an area of "enhancement," the most likely
scenario is a return trip to undergo a double-check ultrasound. If an
abnormality is confirmed, a needle biopsy is sometimes recommended. If
ultrasound of the area in question is completely negative, then a
short-interval MRI might be recommended - or, for more worrisome
enhancements, an MRI-guided biopsy is performed. The chance of a
call-back for further studies is 1 of 5 on the baseline MRI, but only 1
of 10 on subsequent MRIs.
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Are there any other drawbacks to MRI?
COST. MRI is
expensive, though most indications are covered by insurance. It helps if
you check with your insurer, but here are some guidelines: When using
MRI for pre- operative planning in newly diagnosed patients, cancer
follow-up, or diagnostic problems not settled by conventional imaging.
MRI is almost always a covered expense. When MRI is used to complement
mammography as part of an asymptomatic screening program, coverage
varies from insurer to insurer (the latest guidelines for screening are
covered in a following section). When MRI is used to evaluate breast
implants placed for cancer reconstruction, it is a covered expense, but
this is not the case for implants placed for cosmetic purposes, even
though the FDA has recommended MRI every two years for women with
silicon implants.
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Could MRI replace mammography?
No. Breast MRI is to
be used as an additional tool to improve our present combination of
mammography and ultrasound. Also, mammograms are better than MRI at
detecting calcifications, which may be one of the early signs of breast
cancer.
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Who is a candidate for breast MRI?
Newly diagnosed
breast cancer patients. MRI will provide more accurate information about
tumor size and shape, allowing the surgeon to properly plan treatment.
MRI will also help assure that there are no additional areas of cancer
in the same breast or on the opposite side. Women contemplating
lumpectomy often have anxiety about cancer being present in the
remaining breast tissue, and there can be a great deal of reassurance to
know through MRI that the problem is limited to one site. Also, in the
era of "partial breast radiation" (e.g. Mammosite™), the remaining
breast tissue away from the lumpectomy site is not treated, so breast
MRI is an excellent tool to help patients select this approach.
Patients with a past history of breast cancer. Women
who have undergone lumpectomy and radiation often have scar tissue seen
on mammography that can mask a recurrent cancer. Incorporating MRI into
the follow-up plan vastly improves the chances of early detection. For
woman who have undergone mastectomy on one side, there is still a
possibility of recurrence of the original tumor, plus the other breast
is at risk for the development of a new primary breast cancer. Again,
MRI is the most sensitive method of detection. Woman who have already
had bilateral mastectomies may still want to continue with MRI follow-up
if they are at risk of local recurrence, especially if they have
undergone a reconstruction that can interfere with early detection.
Diagnostic problems not settled by conventional
imaging. Usually, breast concerns are completely evaluated through the
use of mammography and ultrasound. However, if question remain, breast
MRI can offer great assistance.
Implant status. Breast implants placed as part of
cancer reconstruction are studied with MRI as part of routine follow-up,
and this is generally covered by insurance. When silicone implants are
placed for cosmetic reasons, the FDA under new guidelines recommends
breast MRI after 3 years, then 2 years thereafter, through insurance
coverage is less likely here (unless patients qualify for MRI based on
other indications).
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So what about asymptomatic screening?
Although the
American Cancer Society previously suggested breast MRI for high-risk
women, detailed guidelines were not introduced until 2007. Yearly breast MRI, in addition to mammography,
beginning at age 30 is now recommended
by the ACS for women who: 1) test positive for one of the BRCA genes, or
a first-degree relative of a known BRCA mutation carrier, 2) have a
documented history of any of rare genetic disorders in which breast
cancer is one components, 3) have a past history of being treated with
chest irradiation for Hodgkin's disease between ages 10 to 30, or 4)
have been calculated by any of the standard mathematical models to have
a 20-25% (or greater) lifetime risk for the development of breast cancer.
The first three indications are straightforward, but
relatively rare. However, if you wonder whether or not you meet the
"20-25% lifetime risk," this usually requires a formal risk assessment
for mathematical modeling. We also believe it's important to review your
degree of mammographic density in making the decision to use MRI
screening. arranging for easier payment strategies. To make an
appointment for risk assessment, genetic counseling, and discussion of MRI screening, call Dr. Hollingsworth at 405-936-5455.
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How do I schedule a breast MRI?
Unless the
radiologist has recommended a breast MRI, you will need a referral from
your doctor. You should bring your mammograms and ultrasound with you at
the time of study if these were done at a facility other than Mercy. Any
biopsy reports should be faxed to us at 405-749-7078. The more
information the radiologist has about your condition the more meaningful
the report to the referring physician will be. For appointments, call
405-749-7077.
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