MAG3 scan

What is a MAG3 scan?

MAG3 stands for mercapto-acetyl-triglycine. This is the name of the injection we give for the scan.

A MAG3 scan is used to:

• look at how well the kidneys are draining
• look for blockages in the kidneys
• compare how well each kidney is working

To do the scan we give your child 2 injections:

• Furosemide, which makes your child’s kidneys produce more pee
• MAG3 to show the kidneys on the pictures made by the scanner

Furosemide is a medicine that makes your child’s kidneys work harder. However, this also increases your child’s need to pee. They should drink lots to keep well hydrated before and also after the test.

The MAG3 injection is a radioactive isotope. This is like a special type of energy that you cannot see or feel, but can be detected by our scanner.

Your child will need to have a small injection into a vein. This is normally done using a small butterfly needle (a small flexible needle) or cannula (a small plastic tube) that goes into your child’s vein. This is usually in the arm, hand or sometimes their foot. This will be taken out after the radioactive isotope has been injected.

This means your child will be slightly radioactive for about 24 hours.

Before the appointment

Please make sure your child has had lots to drink and is well hydrated before the scan starts.

If you are pregnant, or think you could be pregnant, please let a member of the nuclear medicine team know as soon as possible.

If your child is 12 years or older we will need to ask about the possibility of pregnancy.

If your child has any additional needs, please let us know before attending for the scan. This is to make sure that we can provide support and prepare your child for the scan.

Your child does not need to undress for the scan. However, they should wear clothes that do not have any metal as this can interfere with the scan pictures.

It is important that the person bringing your child to this appointment has parental responsibility. If this is not possible, please let a member of the nuclear medicine team know.

Unfortunately, we ask that you do not bring other children to this appointment. If this is not possible, please make sure another responsible adult is available to supervise other children whilst your child has their scan.

How long will it take?

The appointment usually takes around 1 to 2 hours.

Check in at the X-ray reception

Let our reception team know that you are here for a MAG3 scan. This can take around 5 to 10 minutes.

Some children may need to be cannulated in the medical day care unit. Your appointment letter will say if you need to go to medical day care first.

Getting weighed and an injection

A member of the team will weigh your child. This is so we know the correct amount of radioactive injection to give your child and also the correct amount of furosemide.

If your child is over 12 months old, they will be offered EMLA cream to numb their skin beforehand.  This takes around 10 minutes to apply. If your child would like this, we will have to wait an additional hour before giving your child their injection.

If your child is under 12 months, other options are available to help numb the area where the injection needs to go. This will be discussed with you when you arrive on the day.

MAG3 injection and scan

A member of the nuclear medicine team will explain the procedure and then give your child their Furosemide and MAG3 injection. Both medicines are given through the same butterfly needle or cannula. The explanation and injection will take around 15 minutes.

The scan is in 2 parts. We will start the first scan immediately after the injection.

Scan part 1

The first scan takes 25 minutes. We need your child to remain on the scanner for the full 25 minutes. We will ask your child to lay flat on their back with a camera underneath them. Sometimes we also put a camera above them too. All they need to do is lay very still throughout the scan. The picture is taken slowly over 25 minutes, any movement may blur the picture.

You can be with your child throughout the scan.   You can talk to them and hold their hand. They can watch a DVD during the scan, to help keep them still and settled.

We also have some toys for young children to play with.

During the scan, your child will feel a need to pee. Please let the nuclear medicine team know if your child does not have good bladder control (this is not necessary for children wearing nappies).

Waiting

Next, you will need to wait for half an hour after the first scan has finished.

Your child can eat and drink as normal. It is important that your child drinks plenty of fluids. The team will tell you when to return for the scan. If you wish, you can leave the hospital but just make sure you return in time for the second part of your scan.

Scan part 2

The second part of the scan is about 3 minutes. There are no more injections. The team will take pictures to see how the kidneys are working an hour after the injection.

How does the radioactive injection affect my child?

Your child will not feel anything after having their injection. It will not normally make your child feel sick or sleepy. Your child can still eat, drink, and take any medications as normal.

The isotope radiation dose is very small and is measured according to your child’s weight.

Radiation risk

Your child’s doctor has carefully considered the MAG3 scan to be of benefit to your child, considering the risks associated with the radiation exposure. Everyone receives ionising radiation every day from radioactivity in the air, food that we eat and even from space! The amount of radiation associated with your MAG3 scan is small and the associated risk of harm is very low. The radiation dose your child receives from the MAG3 scan is less than 1 years’ worth of background radiation for a person living in the UK.

For more information on the risks of exposure to radiation, please visit Public Health England: Patient dose information.

You are welcome to stay with your child throughout the procedure. However, you may receive a very small dose of radiation. As with your child, the nuclear medicine team will make sure the dose is kept as low as possible and will provide instructions on how to minimise this.

After the scan

If your child is not having any further scans or tests, you will be able to go home.

Your child’s scan will be sent by one of the consultant radiology doctors, to the doctor who asked for your child’s scan to be done.

What precautions should I take when my child is radioactive?

The radioactive injection comes out in the pee. Your child’s pee will be radioactive for about 24 hours.

It is important to:

• make sure your child sits down to use the toilet and flush the toilet straightaway
• wipe up any spills with toilet tissue and flush them away
• wash their hands thoroughly with soap and water
• avoid close contact prolonged with other small children and pregnant people
• your child should not share their bathwater with anyone while radioactive, in case of accidental contamination

If your child uses nappies or pads, you should double bag these along with any wipes and put them in an outside bin.

A member of the nuclear medicine team will advise you about these precautions during your appointment.