| At the hospital you may have to
undergo some other tests used to detect brain tumours. The most suitable test for you will
be selected by your doctor. Computer Axial
Tomography Scan (CT or CAT Scan)
A CT scan is a special type of X-ray. The scanner takes a series of cross-section pictures
of your head, which are then converted by a computer into a detailed picture of your
brain. To increase the detail of the picture, a dye containing iodine may be injected into
a vein, usually in your arm. This may make you feel hot all over for a short while. A few
patients are allergic to the dye and it is important to let the doctor know if you have
any known allergies.
During the scan you will be asked to lie with your head
inside an opening in the scanner. The whole test may take up to half an hour to complete.
It is completely painless and most people are able to go home as soon as the scan is over.
Magnetic resonance imaging (also called MRI or NMR)
This test is similar to a CT scan, but it uses magnetism instead of X-rays to build a
series of cross-section pictures of the brain. During the test you will be asked to lie
very still on a couch inside a metal cylinder, which is open at one end.
The whole test may take up to an hour and is completely
painless. Again the injection of a dye into a vein may be used to improve the image. The
cylinder is a very powerful magnet so before entering the room you should remove any metal
belongings. People who have cardiac monitors, pacemakers or surgical clips cannot have an
MRI because of the magnetic fields. You may feel claustrophobic inside the cylinder and it
can be noisy, but you can usually take someone with you into the room to keep you company.
It may also help to mention to the radiographer doing the MRI if you do not like enclosed
spaces. They can then offer extra support during your test.
Skull X-ray
Very rarely tumours may show up on an X-ray picture or the doctor may be able to
detect signs of raised intracranial pressure from the X-ray. The test is simple and
painless, but you will have to lie on a couch in the hospital's X-ray department and keep
your head very still for a few minutes.
Chest X-ray
A chest X-ray will usually be performed to make sure your lungs are healthy and to
look for a possible primary tumour.
Positron emission tomography (PET) scan
This new type of scan provides a picture of brain activity by measuring levels of an
injection of glucose (sugar) with a tiny amount of a radioactive substance which shows up
on the scan. It is not available at all hospitals. This type of scan may help to tell
whether a tumour is active. It can also be helpful in trying to decide if a tumour is
malignant or benign. When you have a PET scan you will initially have a small needle
inserted in your arm for the injection. The dose of radiation you receive is no more than
a normal X-ray. After your injection, you may be asked to lie quietly in a dark room with
your eyes closed. You will then be taken to the scanning room and asked to lie on a couch
with the scanning ring around you.
If you have any questions about this type of scan it is
important to ask the staff in the scanning department.
Angiogram (also called an arteriogram)
An angiogram shows blood vessels and may show the position of the tumour. This may be
useful information if an operation is planned. First a small tube (catheter) is inserted
into an artery (usually in the groin) under local or general anaesthetic. When the
catheter has been passed into the correct artery, a dye is injected and a series of X-rays
is taken as the dye flows through the brain's blood vessels. You may need to be admitted
to hospital overnight for the angiogram, as it is usually necessary for you to be sedated
or to have an anaesthetic for the test.
Electroencephalogram (EEG)
This is a recording of the electrical activity within the brain. During the test,
wires connected to discs are attached to the head using a special gel. The recorded nerve
impulses are then printed out on paper as waves. The test takes about an hour. It is safe
and completely painless. The hair does not need to be cut and the gel will wash out easily
afterwards.
Biopsy
It is often necessary for the doctor to perform a biopsy to find out exactly what type
of tumour you have. |
