Tests and procedures: X-rays and scans

A number of imaging tests can be done to help diagnose the type of cancer. Aside from diagnosis, imaging tests may also be used for staging or to monitor your child’s response to treatment. 

Bone scan

A bone scan takes pictures of the bones to see if tumour or infection is present. A special dye (a radioactive marker) is given into the vein before the pictures are taken.This dye contains about the same amount of radiation as an x-ray.

  • the dye goes to areas in the bones that are not normal
  • after the dye is injected, some pictures are taken
  • your child will then be asked to come back later for more pictures, (usually about 90 minutes after the injection) - the scan may take up to an hour.

Your child will need to lie still during this test. Some children may need sedation (medicine that makes them sleepy) to help them  lie still for the whole scan.

Some children feel closed in when the scanner passes over their body, but a bone scan itself does not hurt.

Computed Tomography (CT) scan

A  CT scan uses a combination of X-rays and computer technology to produce 3D images of the inside of the body. CT images are particularly useful for planning radiation treatment or surgical procedures. 
 
CT scans help assess the  lungs for signs of metastases (spread of cancer) and infection. It also shows calcifications (the buildup of calcium), which can happen with certain diseases. 
 
During the scan:

  • the child must lie still in a short doughnut-shaped tube
  • a scan can take anything from 30 seconds to 15 minutes to complete, depending on the area of the body being examined
  • contrast dye may be given beforehand (intravenously or orally) to help improve the quality of the images
  • some children need sedation or a general anaesthetic to be able to lie still for the whole scan.

Having a CT scan does not hurt, but your child may become uncomfortable from lying still for a long time.

Gallium/ thallium scan

A gallium or thallium scan takes pictures of soft tissues (like organs and muscles) to see if a tumour or infection is present.

  • A special dye (a radioactive marker) is given into the vein 48 hours before the pictures are taken
  • The dye goes to areas in the body that are not normal
  • Because gallium is absorbed and excreted through the bowel (gut), it is important that your child takes a laxative until scanning is finished, otherwise a full bowel can give false results
  • The scan takes about one hour to complete.

Your child will need to lie still during this test. Some children may need sedation (medicine that makes them sleepy) to help them to lie still for the whole scan.

Some children feel closed in when the scanner passes over their body, but a gallium/ thallium scan itself does not hurt. 

MRI

An MRI uses a special machine (scanner) to look inside the body. The scanner uses radiofrequency waves and a strong magnetic field, rather than x-rays to provide remarkably clear and detailed pictures of internal organs and tissues. 

Your child:

  • will need to lie still on the table inside the MRI machine while the pictures are made (they may be given sedation or general anaesthetic)
  • may not wear anything metal (jewellery, belt, etc) because the machine attracts metal like a magnet.
  • will hear a rhythmic knocking sound, like a drumbeat or loud banging when the machine is on.

You may not be able to stay in the same room with your child during this test however, you and the staff can always hear and see your child. Having an MRI can last from 30 minutes up to two hours.

An MRI does not hurt, but some children might find it loud and may become uncomfortable from lying still for a long time. They may also find the enclosed space of the MRI machine distressing. Medication can be given to calm the nerves and minimise any discomfort if necessary.

MIBG scan

A MIBG scan is used specifically to diagnose and stage neuroblastoma.

For four days prior to your appointment, your child will be given two drops of Lugol’s iodine in milk or orange juice twice a day until scanning is completed.

It is very important that Lugol’s iodine is never given on its own (undiluted) because it can harm the lining of the mouth. It is also given immediately after a MIBG scan to protect the thyroid gland. 

  • a small amount of radioactive iodine is injected (as a radiotracer)
  • the dye goes to areas in the body that may be affected by neuroblastoma
  • 18-48 hours later the scan is complete( pictures are taken showing how the tumour has absorbed the radiotracer)
  • some children may be sedated for the scan 
  • the scan takes about one and a half hours to complete.

Positron Emission Tomography (PET) scan

PET scans are used to detect cancer and to examine the effects of treatment by looking for certain changes in the cancer. 

  • your child will fast for a our-hour period before the scan
  • a small amount of a radioactive tracer is given as an injection into a vein.
  • 45 minutes later, the PET scanner is used to look at where the radiotracer is throughout the body
  • this takes 30-45 minutes 
  • a quick CT scan is performed at the same time as the PET scan, which is used to improve image quality
  • sedation may be required for some children, but the procedure itself is not painful.  

A PET image is colour coded - different colours show various levels of cell activity.
When a CT scan is laid over a PET scan, doctors can pinpoint the exact location of abnormal cell activity.

X-ray

X-rays use radiation to take pictures of solid structures like bones, showing the inside parts of the body.

They can show if a bone is broken, or if there is infection or fluid in the lungs. X-rays do not hurt. 

Ultrasound

An ultrasound uses high-frequency sound waves to ‘show’ structures inside the body. An ultrasound is painless. 

Clear jelly is placed on the part of the body being examined and a small round handle is placed on the jelly and moved around to get a clear picture of the tissue or organ. 
 
Some ultrasounds require special preparation. For example, when the pelvis is being examined the bladder must be full. For this reason, the child will need to drink plenty of fluid and will be asked to not go to the bathroom to empty the bladder until the ultrasound is over.

With younger children, this may not be possible. Older children  may become very uncomfortable from having a full bladder. 
 
Gas interferes with ultrasound imaging, so it is important that the fluids taken before the ultrasound are not carbonated (fizzy drinks). 

Last updated Wednesday 26th June 2024