3T High field MR system
Frequent asked questions (FAQ)
Explanations hereafter are adapted to the high
field MRI we use in our institute. Some of these
comments cannot be applied to other MRI systems. If you are to be
examined elsewhere, please ask for specific information.
- What should I do if I think I might be be
- Is it necessary to be fasting for an MRI? How
should I prepare?
- Should I expect MRI time to be delayed?
- My body harbours some metal elements
- Can you accept obese patients?
- I am allergic
- I suffer from a cold
- I am very claustrophobic and I think that I
wouldn't even enter your MRI
- I cannot tolerate binds
- Will you let me alone inside?
- Why do you maintain the MRI door closed?
- I cannot stand loud noise
- Why are MRI sequences so noisy?
- Shall I feel something during my MRI
- Could MRI induce changes in my body?
- Why is MRI imaging lasting so long?
- Why cannot I move during MRI sequences?
- May I read or do something else during MRI?
- Is your MRI able to perform every usual
- Is image quality higher than other
- Is MRI able to diagnose any disease?
- Why are MRI images not colored?
- Why is MRI imaging fairly costly?
- I am not sure that my insurance will
reimburse my MRI examination
- Do you perform MRIs without medical
- Will you tell me my result at the end of
- Shall I get my MRI CD-ROM?
- I brought older X-rays along...
- I have lost my MRI films...
- I have a pacemaker: is it still possible to
undergo MRI ?
- I have a cardiac valve: is it safe ?
- I have tattoos / piercings
- Do I really need an injection ?
What should I do if I think I might be be pregnant ?
Although MRI has been proven to be innocuous and does not
any dangerous radiation, MRI imaging
is not adviced during the first two trimesters of pregnancy. This rule
may be simply ignored if a
life-threatening disease has to be investigated.
Is it necessary to be fasting for an MRI? How should I
You do not have to be fasting for MRI, except for abdominal
imaging. You may in any case take your daily drugs with a little water.
Please do not make up, especially for head and neck examinations and
remember that all jewels included piercings need to be removed before
Should I expect MRI time to be delayed?
MRI imaging is a complex technique and schedules may sometimes
be disturbed by unforeseen events. It may happen that you are asked to
wait a little for your turn. That is why we advise you to schedule at
least two full hours for your MRI to complete.
My body harbours some metal elements
If you are harbouring a pacemaker or another electronic
implant (insulin pump, for example), any metal element in your head or
close to your eyes, please contact us quickly to decide if your MRI
should be cancelled. For any other metal object location, there is no
danger; please just mention it to the technician in charge of your
examination. Plastic implants should not interact at all with MRI.
Can you accept obese patients?
Our MRI, open on all sides, is specially fitted for obese
patients, when they cannot always enter a closed MRI "tunnel". Upper
weight limit is 135 Kilograms.
I am allergic
It is important to mention any allergy or drug intolerance, in
case we have to administrate contrast agent. Gadolinium used in MRI is
very rarely allergenic, even less than already safe modern iodinated
contrast agents used for example in CT-scan imaging.
I suffer from a cold
As coughing may induce movement artefacts and alter image
quality, we advise you to call us and delay your date.
I am very claustrophobic and I think that I won't be able to undergo an MRI
sensitive patients can still manage to undergo MRI with some help.
Thanks to high field and tenchnology, it is possible to program very
short sequences. Our patients are always handled with
patience and understanding, nobody being forced into the magnet. In
most difficult cases, we propose short-termed sedation with very good
efficacy against anxiety. That is why we recommend anxious patients to
ask someone to drive their car back, because in case they would
receive sedation, no driving is allowed for a few hours.
I cannot tolerate binds
Patients are never attached during MRI. We only secure the
part to be examined with cushions against unintentional movements. You
would be able anytime to get out of MRI by yourself if you felt it
Will you let me alone inside?
If you come with someone else, he (she) may stay along with
you during your examination. The technician will anyway watch at you
all the time and is able to hear you and speak to you with a
microphone. For further security, an alarm is placed in your hand to be
pressed if necessary.
Why do you maintain the MRI door closed?
MRI uses receiver antennas which are very sensitive to the
weak radio waves emitted back from your body during a sequence. Radio
waves coming from outside must be filtered out by a continuous
shielding, which would be interrupted by opening the door during the
sequences, leading to image quality deterioration. Anyway, the door can
always be openend from inside if necessary.
I cannot stand loud noise
MRI sequences are less noisy in this high field MRI. If noise
is still a problem,
just ask for extra ear protection.
Why are MRI sequences so noisy?
Noise is generated by very fast inversion of electric current
in radio waves emitters used to obtain images. There are no moving
parts inside an MRI device.
Shall I feel something during my MRI examination?
Most people do not feel any difference between being inside or
outside MRI. Very rarely, highly sensitive persons mention slight
sensations in their body, rarely unpleasant and never painful. In very
fields, some feelings may be a little more frequent, like dizziness,
metallic taste in the mouth, heating. With very high
gradient frequency, sensations may be related to low currents generated
in nervous fibers. But these phenomena are safe anyway, thanks to
severe security thresholds limits.
Could MRI induce changes in my body?
High magnetic field and electromagnetic waves (radio waves)
induce multiple short-timed magnetic orientation changes of a small
minority of your body atoms. Under normal examination conditions, no
adverse effects have ever been proved, even in foetuses. We have now
more than 20 years experience and tens of millions of MRIs are
performed every year in the world, showing that this technique is safe.
In addition, every MRI machine is severely controlled in a regular
manner to ensure safety and stable image quality.
Why is MRI imaging time consuming?
An MRI is composed of sequences (usually 5-7) , each about 2-3
minutes of duration necessary to ensure image quality. Every sequence
corresponds to one orientation in space (transverse, sagittal or
coronal), each one with two possible tissue contrasts parameters (T1 or
T2 weighting). Sometimes sequences must be repeated after contrast
agent injection. Mean acquisition time is about 20 minutes, plus time
for patient explanations and installation, eventual contrast injection,
deinstallation and pauses between sequences. Furthermore, if the
patient has moved during a sequence, this sequence needs to be
repeated, prolonging examination time.
Why cannot I move during MRI sequences?
Most sequences need a few minutes to complete; during this
time, MRI builds a very precise body map to obtain an image. Any
patient movement during this period will produce blurred image with
information loss. Image formation can be compared to a photography by
night, for which a long exposition time is necessary to gain enough
light to impress the film (where light is compared to the MRI signal).
The shorter the sequence, the less signal is obtained and the less
precise the image will be.
May I read or do something else during MRI?
It is theoretically possible. But practically, even head
movements or page turning could provoque whole body movement and image
spoiling. That's why we prefer that the patient takes advantage of this
time to rest and relax; it is sometimes even possible to sleep.
Is your MRI able to perform every usual imaging?
More than this: any special technique is available, like MR
angiography, breast MRI and multiparametric examinations.
Is image quality higher than other systems ?
quality at our 3T system is the highest available in the market. Many
MRIs are still working at lower fields, like 1.5 or even lower. Our
high field MRI allows very precise images and shorter examination time.
Is MRI able to diagnose any disease?
MRI is a very potent diagnostic tool for a wide medical
application domain. However, there are diseases that do not appear on
imaging, either because changes are too weak to be recorded, or because
they simply do not induce enough body tissue changes. Lesion detection
is also limited by size, as submillimetric abnormalities may be
difficult or impossible to see.
Why are MRI
images not colored?
The image computed from the different signal intensities
measured in each point of the body (pixels) is coded in gray levels by
the apparatus, whether it is for MRI, CT scan or ultrasound. As
intensity is the sole variable, the computer cannot decide by himself
which color he will attribute to different tissues: two tissues having
the same intensity may be totally different, like liver and spleen for
example; conversely, two structures showing different signals can
belong to the same tissue, like a cyst in the liver. The job of the
radiologist is to distinguish a tissue from another along with their
anatomic location in the body, which a computer hardly could realise.
For aesthetical purposes, a non medical journal may decide to add color
to a radiological image placed on its front page; however, color
neither does enhance details nor refine the diagnosis for the
specialist. If, on the other hand, another variable is obtained, like
isotope radioactivity in nuclear medicine (scintiscanning, PET-CT), or
blood flow in the vessels, as for color Doppler, it is very beneficial
to superimpose a color coding of this dynamic variable on the b/w
images. This procedure can also be carried out in functional MRI, in
which blood flow or regional activity of the brain can thus be better
Why is MRI imaging fairly costly?
MRI costs are determined by the high price of the machine, of
its installation (magnetic shields) and yearly maintenance. Life
expectancy of an MRI installation varies from 5 to 10 years.
Moreover, technician full time presence is required for each
examination, which duration is about half an hour. Lastly, image
interpretation need special medical training because of MRI complexity.
MRI costs are largely compensated by its high diagnostic performance
allowing to obviate many other painful or complex investigations.
I am not sure that my insurance will reimburse my MRI
If your MRI is medically justified, you should not worry: your
insurance has to endorse diagnostic costs prescribed by your doctor.
However, your insurance may ask your doctor to explain his diagnostic
strategy. In very peculiar cases, it may be useful to ask your
insurance before scheduling MRI.
Do you perform MRIs without medical prescription?
Insurance reimbursement will occur only for a medically
prescribed MRI. If you choose to pay your MRI by yourself, you will
have to indicate us to which referring physician we should send the
medical report, so that you can get medical advice based on MRI
Will you tell me my result at the end of examination?
Patient is the first owner of his medical data and it is his
right to have access to it. Anxious patient reassurement is often
possible just after MRI achievement if the result is obvious. However,
radiologists prefer to let the referring doctor inform his patient
himself, because he knows him better and will be able to comment the
results and propose a treatment. Radiologists often refrain from
talking about treatment with their patients because they only have a
partial view of one's problems and are not aware of all possible
treatments in every medical speciality.
Shall I get my MRI CD-ROM ?
If you have a medical visit the same day, you may go along
with your images for your consultation. Otherwise, we can send the
images with the report directly to your doctor. Written results will be
sent to your physician, usually in the next 24 hours.
I brought older X-rays along...
This was the right decision, because we need older exams
(X-rays, ultrasound or CT-scan) relating to the same medical problem
for comparison. After reporting on your MRI, we will send the whole
file to your referring doctor, who will eventually return it to you
on your next consultation. We don't archive any patient documents in
I have lost my former MRI
Your medical data are unique, they belong to you and it is up
to you to carefully preserve your images against light and humidity for
10 years or more if required. For comparison sakes, most images can now
be saved in a PACS (Picture Archive and Commmunication System) at the
I have a pacemaker: is it still possible to undergo MRI ?
MRI is fondamentally incompatible with any electronic
implanted device, which could be damaged or could not function
correctly and cause severe harm to the patient. However, some recent
devices may be switched off or into a "MRI-compatible" mode. This can
only be accomplished when one knows exactly which model is implanted,
when the MRI is officially allowed for this use and when a specially
trained doctor is present during examination. These conditions are
already met in a few centers. You are encouraged to call for
I have a cardiac valve: is it safe?
Most cardiac valves are MRI compatible but older models could
be a problem. You should ask your cardiac surgeon before making an
I have tattoos / piercings
Metals contained in some tattoo inks may induce heating under high
field MRI. Please mention any tattoo at your arrival. All piercings
should be removed before coming, if possible.
Do I really need an injection ?
Injecting contrast medium - usually a Gadolinium complex -
into a vein is used to enhance lesion detection. Such information can
be necessary in many situations
(inflammation, tumor, blood flow disturbance, etc.). Side effects like
nausea, allergy ot intolerance are extremely rare. The radiologist
decides in which case injection will be beneficial for the diagnosis.