Cardiac MRI and CT scan under General Anaesthetic

Radiology Department

Information for patients, parents and carers

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Cardiac MRI and CT scan under General Anaesthetic – PIAG 236 (244kB pdf)

Introduction

This leaflet has been designed to give parents and carers as much information as
possible about their child’s visit to Alder Hey for a cardiac Magnetic Resonance Imaging
(MRI) and Computerised Tomography (CT) scans under general anaesthetic.

MRI is a way of looking inside the body without using x-rays. It is a very safe imaging method with no known side effects. It uses a super-conducting magnet which produces a very strong magnetic field. MRI scanning can acquire images from almost every angle with the patient lying supine.

For safety reasons, you are asked to remove all metallic objects (Hearing aids, clips, jewellery etc) before an MRI scan. It is also important that we are aware of any metal inside your child’s body (surgical clips, pacemakers etc). If your child is having an MRI scan, please complete the safety checklist which accompanies this leaflet, and bring it with you when you come for your scan.

CT uses several beams of X-ray at the same time, from different angles, to give a detailed picture of the inside of the body. CT is very quick but does deliver a dose of radiation. Soft tissue detail is much clearer on MRI than on a CT scan. Occasionally it is not possible to obtain all the information required from either type of scan alone. If this is the case we will move the child from one scan room to the other whilst still asleep

Why is general anaesthetic needed?

Cardiac MRI takes between 60-90 mins, during this your child needs to lie very still
and be able to control their breathing. This means being able to hold their breath for periods of time so the heart and blood vessels remain in the same place whilst the
scans are being acquired. Children above the age of 10yrs can usually achieve this,
but younger children need an anaesthetic.

Cardiac CT is much quicker but your child must be able to hold their breath as the
heart and blood vessels need to be in the same place for the scan, so the anaesthetic
will be much shorter.

Before your appointment

Your child will not be able to eat or drink for a number of hours before their anaesthetic.
Your appointment letter contains fasting instructions. Fasting reduces the risk of
vomiting during and after the procedure, which can cause severe and long term lung
damage. If your child is on any essential medication, this should be taken as normal (with a sip of water, if necessary) on the day of your child’s scan

What happens on arrival?

You should attend either ward 1C or the Radiology Department, as instructed on
your letter Here you will be prepared for the anaesthetic and your child will be weighed,
observations recorded and local anaesthetic cream applied if required. You will be seen
by the Anaesthetist who will be looking after your child during the scan, who will explain
the procedure and get your consent.

Waiting with your child

We encourage you to bring along your child’s favourite toy / activity to help them
relax. You may be in the hospital for several hours. We do our best to avoid long waiting
times, but there are some delays which cannot be avoided. Scans can take longer
than expected, or emergency cases sometimes need to be added to the list at
short notice. You will be kept informed of any delays. Two parents / carers can stay
with your child in the ward, but there is only room for one parent in the anaesthetic
room with your child. As soon as your child is asleep, you will be asked to return to
the ward.

Two parents / carers will be called to the recovery area as soon as your child has
woken up

How does my child go to sleep?

If a needle is inserted while your child is awake, some medicine can be given into
the needle to make your child sleepy. This normally takes about 10-20 seconds.
Alternatively, the Anaesthetist may get your child to breathe in a mixture of gases which
will make them sleepy over 30 seconds to a minute.

What happens during the scan?

Once asleep the anaesthetist will escort your child into the MR scan room, ECG
leads will be put on your child’s chest and a light rectangular plastic device containing
radio frequency coils over these leads.

These coils receive the MR signal and send it to the computer to be converted into
pictures. CT scanning also requires the use of ECG leads so the scan can synchronise with the heart rhythm for clear pictures. The Anaesthetist continually observes and
monitors your child throughout the procedure, and gives anaesthetic medicines
as they are required.

If my child has to have an injection will it hurt?

If your child needs a needle to allow medicines and fluids to be given during the
scan, it is usually painless, because the anaesthetic cream applied during your
assessment numbs the skin over the vein after 45 mins.

What happens after the scan?

When the scan is finished your child will recover in our recovery area, you will be
called from the waiting room or ward to be with them. It usually takes around 10 mins
for children to wake up but they may remain drowsy for some time afterwards. You will
then accompany them back to the SDC (Surgical Day Care) or Ward 1C to recover
fully.

Please be prepared to wait on the ward for between 2-4 hrs until your child is
fully recovered and able to eat and drink. Your child will then be discharged home by
a doctor or a nurse. Some children, usually those with more complex conditions or other
health problems, will need to stay in hospital longer or overnight. If this is the case the
anaesthetist or other doctors will explain the reason for this.

This leaflet only gives general information. You must always discuss the individual treatment of your child with the appropriate member of staff. Do not rely on this leaflet alone for information about your child’s treatment.

This information can be made available in other languages and formats if requested.

PIAG: 236