A bone scan is a nuclear medicine imaging test that uses bone-seeking radioactive materials or tracers (radiopharmaceuticals) and a computer to create an image of the skeleton (bones). A bone scan looks at the bones to see if there are any abnormalities, such as a fracture, tumour or infection.
This test is also called bone scintigraphy.
Why a bone scan is done
A bone scan may be done to:
- look for problems in the bones (skeletal system):
- avascular necrosis (a disease that causes the bone to collapse because of a problem with its blood supply)
- Bone scans can show lesions (abnormal areas) in the bone 6–12 months before they would appear on an x-ray.
- assess fractures or injuries
- find the cause of unexplained bone pain
- find out if cancer has spread (metastasized) to the bone
- Bone scans are not usually done for small tumours, when it is unlikely that cancer has spread to the bones.
- find out if cancer treatment is working
How a bone scan is done
The scan is usually done as an outpatient procedure in the nuclear medicine department of a hospital. No special preparation is usually needed.
- It is important for a woman to tell the nuclear medicine staff if she is breast-feeding, pregnant or thinks she may be pregnant before having any nuclear medicine test.
- The person may be asked to wear clothing that has no metal zippers, belts or buttons. They may be asked to change into a gown during the test and remove glasses, jewellery or objects that could interfere with the test.
Before the scan, the doctor will take a history of:
- bone infections
- surgery to the bone, including devices inserted in the bone
- recent therapy, such as antibiotics, chemotherapy, radiation therapy, bisphosphonates or steroids
- current symptoms
- physical findings
The bone scan test has 2 stages: the radiopharmaceutical is given by injection (sometimes scans are done at this time), and then the person returns later for scans.
Giving the radiopharmaceutical
A radiopharmaceutical is injected into a vein in the hand or arm. Technetium 99m (Tc-99m) is usually the radiopharmaceutical used.
- The radiopharmaceutical travels through the blood and collects in bone, especially in areas of increased activity (where the bone is growing, breaking down or repairing itself).
- Sometimes images are taken right after the injection.
- Giving the radiopharmaceutical usually takes 15 minutes.
To get better images, the person may be asked to:
- drink at least 2 glasses of fluid after the injection and before the scan (unless contraindicated)
- urinate as often as necessary and empty the bladder just before the scan is done
Taking the bone scan
Bone scans are taken after the bones absorb the radiopharmaceutical (2–4 hours after the injection). The scan usually takes 30–60 minutes.
- The person lies very still on a table while the scanning machine and a gamma camera move back and forth over their body.
After the scan, the radioactive material quickly loses its radioactivity. It passes out of the body through the urine or stool (feces). Depending on the type of radiopharmaceutical used, it may take a few hours or days to completely pass out of the body.
- Drinking fluids after the procedure helps flush the radiopharmaceutical from the body.
- Instructions may be given for special precautions that need to be taken after urinating, such as to flush the toilet twice and to wash the hands thoroughly.
Potential side effects
The dose of x-rays or radioactive materials used in nuclear medicine imaging can vary widely. Dose depends on the type of procedure and body part being examined. In general, the dose of radiopharmaceutical given is small and people are exposed to low levels of radiation during the test. The potential health risks from radiation exposure are low compared with the potential benefits. There are no known long-term adverse effects from such low-dose exposure.
Some potential side effects that might occur include:
- Bleeding, soreness or swelling may develop at injection site.
- Allergic reactions to the radiopharmaceutical may occur, but are extremely rare.
What the results mean
A bone scan can detect many disorders. The images produced show increased activity in the bone.
- Bone breaks down and repairs itself for many reasons. Increased activity does not necessarily mean that there is cancer in the bone.
- Tumours in the bone can show up as increased activity because cells are dividing rapidly.
- Doctors may suspect bone metastasis if there are numerous active areas.
- Other bone problems, such as arthritis or fractures, can also attract the radiopharmaceutical and show up as active areas on the image.
Further investigation may be necessary to rule out other abnormalities, especially if a single area of increased activity shows up.
- Bone scans are often combined with prior bone scan, x-ray, CT or MRI imaging and laboratory test results.
What happens if a change or abnormality is found
The doctor will decide whether further tests, procedures, follow-up care or additional treatment are needed.
Special considerations for children
Being prepared for a test or procedure can reduce anxiety, increase cooperation and help the child develop coping skills. Parents or caregivers can help prepare children by explaining to them what will happen, including what they will see, feel and hear during the test.
- Explain to children that when the radiopharmaceutical is given they will feel:
- a sharp prick when the needle is inserted
- slight pressure or tugging when the radiopharmaceutical is injected
- Children need to lie still on the exam table during the scan, which may be unpleasant for them.
- Some children may need sedation to lie still for the whole test.
- Some children may like to hold a special toy or blanket during the scan.
- Children could listen to music or a story during the scan.
- The parent or caregiver can stay with the child and help them lie very still.
- Pregnant women cannot stay in the room during the scan.
- Some children feel closed-in when the scanner passes over their body. Reassure them that the scan does not hurt and will not last very long.
Instructions may be given for special precautions that need to be taken when caring for children during the first 6–24 hours after the test:
- If the caregiver is pregnant, someone else should do most of the child care.
- Wear disposable, waterproof gloves when handling the child’s urine, stool or vomit, including diaper changes.
- Change sheets or clothing that has vomit, urine or stool smears on it.
- Wear disposable, waterproof gloves when handling sheets or clothing.
- Sheets and clothing can be washed in the regular laundry.
- Flush the toilet immediately after use by the child.
- Place diapers in the outside garbage.
The preparation for a bone scan depends on the age and experience of the child. Find out more age-specific information on helping children cope with tests and treatment.