Magnetic Resonance Imaging (MRI) is a technique that uses
radio-waves and a powerful magnetic field to produce images of the
breast. No x-rays are involved.
Ascot Radiology have now installed a new generation machine that
uses a powerful 3 Tesla magnet to produce very detailed images.
Dedicated breast coils are used to provide optimal images of the
breast. These pictures are then processed by a computer and can be
stored and analysed in various ways. Computer aided diagnosis (CAD)
improves accuracy and versatility of this investigation.
The biggest problem with MRI in the past has been that we did
not have a method for localising small MRI detected abnormalities
for biopsy. The new machine has an MRI guided biopsy system that
solves this problem. The system uses a computer to accurately
calculate the coordinates of an abnormality within the breast and
then guides a biopsy needle into the correct location through the
skin and breast tissue. This biopsy is done using local
MRI does not replace clinical examination, mammograms and
ultrasound in routine diagnosis, but now plays an important part in
providing more accurate assessment of certain situations.
Indications for MRI:
1.Pre-op planning for breast conserving
surgery. In some situations MRI can provide a better
estimate of the size and extension of a tumour than mammography or
ultrasound. This applies particularly in younger women with dense
breast tissue. MRI can also detect other areas of cancer in both
breasts. Multifocal or bilateral cancer will require more extensive
2. Surveillance after breast cancer surgery.
This can be difficult due to scar tissue and distortion of the
breast. MRI can sometimes be useful in distinguishing recurrence of
the cancer from post-operative scar tissue.
3. Screening high-risk younger women. Early
studies suggest that MRI may be more accurate in finding cancers
than mammography in high-risk women. This increased detection has
not been shown as yet to translate into a lower mortality. MRI
screening does produce more false-postitive results that may
require further procedures including surgical biopsy.
4. Assessment for implant rupture.
False positives - One of the drawbacks of MRI is that
it is very sensitive and consequently often finds abnormal areas
that are not due to cancer. These false positives can create a lot
of anxiety and result in additional investigations and biopsy.
False negatives - Like all imaging investigations MRI
is not 100% accurate. It can miss some cancers and create a false
sense of security. It remains important to review MRI imaging in
conjunction with other tests and to ensure that concordance is
achieved. Careful follow-up using other established imaging
modalities such as ultrasound and mammography may still be
MRI examination requires the patient to lie on her stomach with
the breasts hanging freely through cushioned openings. The
examination table is then moved into a hollow cylinder surrounded
by the large magnet. Multiple images are taken over a period of 30
- 60 minutes. You will need to remain very still while images are
taken. If you suffer from claustrophobia or severe anxiety a mild
sedative can be administered for this procedure. Intravenous
contrast may be used for some of these sequences.
Patients with some metallic devices may not be suitable for this
Advise the radiologist if you think you may be pregnant.
MRI scanning is a valuable tool in our armamentarium for the
assessment and management of breast problems. We are fortunate to
have access to the latest technology in this area.