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What is Magnetic Resonance
Imaging? |
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Magnetic Resonance Imaging
or MRI is a scanning technique which produces very clear, detailed
pictures of the brain (and other parts of the body). These pictures
are much more detailed than those from other scanning techniques.
By using a combination of new techniques to acquire MRI scans and
subsequently to process the data, it is possible to identify the
causes of seizures in most people whose epilepsy arises in one part
of the brain. Small tumors, developmental abnormalities, abnormal
blood vessels and minor brain damage are now routinely visualised
and it is now possible to diagnose more subtle abnormalities which
may also cause epilepsy. |
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It is important to remember
that MRI is a diagnostic technique and not a form of treatment. |
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How does MRI work? |
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MRI uses a very strong magnetic
field, far stronger than the earth's magnetic field, and scans the
hydrogen protons within the human body. Very sophisticated electronic
hardware and computer software is then used to produce the images
on to both a computer screen and onto film so that they can be studied
by a specialist. |
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Why are MRI scans helpful
in epilepsy? |
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An MRI scan gives far better
anatomical details than other diagnostic techniques and in epilepsy
this has meant that even very small abnormalities, which may have
been missed by other scans, can be seen. In some people, it is possible
to remove the abnormal area by neurosurgery. In clinical practice
MRI, is now an essential investigation providing information about
cause, prognosis and type of epilepsy. |
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Are then any side effects
from MRI? |
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Unlike with x-ray, MRI
is not known to have any harmful side effects. |
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What is involved in
having an MRI scan? |
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Before having a scan, it
will have to be determined whether there is any reason why a scan
should not be carried out and a form will have to be completed.
Because of the strong magnetic field people with pacemakers, cerebral
aneurysm clips and some other surgical implants will not be able
to have an MRI scan. Before having the scan any jewelry, hairclips,
hearing aids, credit cards, coins, or keys which could interfere
with the scanning procedure will have to be removed. The person
undergoing the scan will be asked to lie down on a flat surface
which will then move inside the scanner. The procedure is painless
but ear plugs are usually available as the noise made by the scanner
is very loud. A two-way intercom means that there is constant contact
whilst the scan is being carried out. Usually the scan will last
about half an hour and all the person has to do is to keep as still
as possible. |
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What else is MRI used
for? |
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In addition to providing anatomical
pictures, research is showing that MRI potentially has other uses.
For instance, with MR spectroscopy, it is now possible to measure
the amounts of various chemicals within the brain, which gives information
about the health and viability of brain cells, and to determine
how and where in the brain, these are affected in people with epilepsy.
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How can someone be referred
for an MRI scan? |
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The possibility of having
a scan should be discussed first with the doctor managing the
epilepsy treatment. A medical referral either from the GP or
consultant will be needed. |