A bone scan is a test to check for problems inside your bones, such as arthritis, infection and cancer. A bone scan can often find problems days to months earlier than a regular X-ray can.
When is a bone scan performed?
Your doctor may order a bone scan if you have bone pain and/or if they think you have a problem with your bones, such as:
- certain types of fractures
- infection involving the bone (called osteomyelitis)
- Paget’s disease of the bone
- certain types of cancers such as bone cancer
- to see if cancer from other parts of the body have spreads to the bone.
How is a bone scan performed?
A bone scan is normally done by a nuclear medicine technologist. Your results will be interpreted by a radiologist or nuclear medicine specialist.
Before your scan, you will need to remove your clothing and jewelry. You will be given a gown to wear.
The technologist will inject a small amount of a radioactive dye into a vein in your arm. The dye travels through your bloodstream and into your bones. It takes about 2 to 3 hours for the dye to be absorbed into your bones.
When it is time to do your scan, you will be asked to lie on a table where a large camera called a scanner will measure how much dye has been absorbed by your bones. You will be asked to move into different positions and hold very still so the camera can take pictures of all sides of your body. A digital image is produced by the scanner which a radiologist or specialist uses to interpret your results.
A bone scan takes about 1 hour.
What do the results mean?
The amount of dye that is absorbed depends on the amount of growth or activity in the bone.
- Test results are considered normal when the dye is spread evenly throughout the body. This means that you are unlikely to have any major bone problems.
- Areas that absorb little or no amount of dye appear as dark or "cold" spots. This could show a lack of blood supply to the bone or certain types of cancer.
- Areas of rapid bone growth absorb more dye and show up as bright or "hot" spots in the pictures may indicate problems such as arthritis, a tumour, a fracture, or an infection.
Image: Bony metastases from prostate cancer shown by a bone scan. (Image by RadsWiki via Wikimedia Commons)
How to prepare for a bone scan
A bone scan does not need any special preparation.
- Wear loose, comfortable clothing, avoiding garments that have zippers, belts or buttons made of metal.
- You may also be asked to remove jewellery, removable dental appliances, eye glasses and any metal objects or clothing that might interfere with the scanner.
- It takes 2 to 3 hours for the dye to spread to all bones in your body. Once you receive the injection you may be allowed to leave the hospital.
- You may eat, drink, or take any medication after your injection. The technologist will tell you what time to return to the hospital to have your scan done.
What to expect after a bone scan?
Bone scans do not generally cause any after effects. The dye does not remain active in your body. It passes out of your body through your urine over about 24 hours. You may be instructed to take special precautions after urinating, to flush the toilet twice and to wash your hands thoroughly. You will be advised to drink plenty of water for a day after the scan to help flush the dye out of your system.
A radioactive injection sounds dangerous, but only a small amount of radiation is given to you. A bone scan poses no greater risk than conventional X-ray procedures. However, the test may be unsafe for pregnant or breast-feeding women as there is a risk of injury to the fetus and of contaminating the breast milk.