Foetal MRI

Author: Dr Michelle Fink*

What is a foetal MRI?

Magnetic resonance imaging (MRI) is a way of taking detailed pictures of the inside of the body. It is useful for looking at many parts of the body. A foetal MRI gives additional information about your baby from the information received from an ultrasound scan that will have been carried out routinely during your pregnancy.

During an MRI scan, pictures are taken from different angles and a computer processes these to produce a detailed image of the part of your baby being scanned. MRI uses a strong magnetic field and radio waves to obtain the pictures. It does not use radiation.

Foetal MRI must not be carried out in the first trimester of pregnancy because diagnostic accuracy is much less at that time.

How do I prepare for a foetal MRI?

Wear loose, comfortable clothes with no metal. Any body piercing must be removed. The following items are affected by the magnet and are not permitted into the scanning room for safety reasons: watches, pens, keys, jewellery, hair pins, safety pins, mobile phones, credit cards, pagers, radios and CD players.

Any person accompanying you into the scanning room will also need to remove metal objects to ensure your safety and theirs.

Try and avoid caffeine (coffee, tea, cola drinks) and fizzy drinks on the day of your foetal MRI, as this will help your baby be less active. Bring your partner or a friend to keep you company.

What happens during a foetal MRI?

Before entering the MRI room, you will be asked to complete an MRI questionnaire. It asks about your medical history and helps the MRI department ensure your safety. Someone will go through the questionnaire with you and answer any questions you have. The MRI scanner is like a big square box with a tunnel through the middle. During an MRI scan, you have to lie very still in the tunnel, usually on your back, but if this is not possible you may be able to lie on your side.

The table that you lie on is narrow. You can see what is happening through mirrors and you can talk to the MRI technologist carrying out the scan. At times, you may be asked to hold your breath for a short time.

Foam cushions and soft straps are used to help you keep still. A soft flexible wrap goes over your stomach and records the radio waves for the pictures. You can wear headphones to muffle the loud ‘knocking’ noise of the machine. Some people feel warm during the scan; this is normal, and wearing loose clothes will help.

No injections are used during the procedure as a routine. Some MRI facilities will give mild intravenous (injected into a vein) sedation to the mother. This is completely harmless to the foetus and is a mild version of Valium, which helps to relax the mother and reduce rapid foetal movement, which can improve image quality.

Are there any after effects of a foetal MRI?

There are no after effects of a foetal MRI.

How long does a foetal MRI take?

The scan usually takes 30 to 45 minutes.

What are the risks of a foetal MRI?

There are no known risks of foetal MRI to either the mother or the unborn baby.

What are the benefits of a foetal MRI?

MRI can give your doctors additional information to any ultrasound scans you have and will help them understand how your baby is and explain this to you.

Who does the foetal MRI?

The foetal MRI is carried out by a radiographer who specialises in taking MRI pictures. They will make sure you understand what is going to happen and make you comfortable on the MRI table. They will talk to you through a microphone during the procedure. A radiologist (specialist doctor) who will read the MRI pictures will often be with the radiographer, guiding them in obtaining the pictures needed to write a report for your doctor. Neither the radiographer nor the radiologist will be able to tell you the results of your scan before you leave, as the radiologist will have to take a long time to look at all the pictures before issuing the final report.

Where is a foetal MRI done?

A foetal MRI will usually be carried out in the imaging department of a hospital that specialises in doing foetal MRI.

When can I expect the results of my foetal MRI?

The time that it takes your doctor to receive a written report on the test or procedure you have had will vary, depending on:

• the urgency with which the result is needed;
• the complexity of the examination;
• whether more information is needed from your doctor before the examination can be interpreted by the radiologist;
• whether you have had previous ultrasound or MRI examinations that need to be compared with this new test;
• how the report is conveyed from the practice or hospital to your doctor (i.e phone, email, fax or mail).

Please feel free to ask the private practice, clinic, or hospital where you are having your test or procedure when the written report will be provided to your doctor.

It is important that you discuss the results with the doctor who referred you, either in person or on the telephone, so that they can explain what the results mean for you.

Useful websites about foetal MRI:

The Royal Children’s Hospital Melbourne – Kids health info for patients:
www.rch.org.au/kidsinfo/fact_sheets/MRI_Fetal

*The author has no conflict of interest with this topic.

Page last modified on 26/7/2017.