A radiotracer, or bone-seeking radionuclide is injected into a peripheral vein. The radiotracer emits gamma radiation as it decays, which is detected by a camera. When the tracer has collected in the bones (about 2-3 hours) after the injection, the scan is performed. Information from the camera is recorded in a computer, which then processes the data and creates an image.

Normal distribution areas appear uniform and gray. "Hot spots" are areas where there is increased bone uptake (accumulation) of the radiotracer; these appear black. "Cold spots" are areas where there is less uptake of the radiotracer. These appear light or white. The scanning part of the test will last about 1 hour and may require moving to various positions.

You must remove jewelry and other metal objects. You may be asked to wear a hospital gown.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:

• Infant test or procedure preparation (birth to 1 year)
• Toddler test or procedure preparation (1 to 3 years)
• Preschooler test or procedure preparation (3 to 6 years)
• Schoolage test or procedure preparation (6 to 12 years)
• Adolescent test or procedure preparation (12 to 18 years)

There is a small amount of pain when the needle is inserted. During the scan there is no pain. You must remain still during the examination, and you will be instructed when to change positions by the technologist.

Detecting areas of abnormal bone metabolism is valuable in determining whether there is associated tumor, fracture, infection (osteomyelitis), or an underlying metabolic disorder.

Normal radiotracer uptake appears uniformly gray in the bones. There should be no area of asymmetric increased or decreased distribution of the radionuclide.

Some abnormalities that may be identified on radionuclide bone scans include:

• Tumors that have spread from other parts of the body to the bone (metastatic disease)
• Primary bone tumors
• Fractures
• Bone infections (osteomyelitis)
• Degenerative diseases of the bones, such as arthritis
• Rickets
• Fibrous dysplasia
• Paget's disease
• Avascular necrosis
• Radiation changes

It is important to understand that bone scan findings must be correlated with other imaging studies, in addition to clinical information. You should always discuss the significance of abnormal findings with your health care provider.

If you are pregnant or nursing, the test may be postponed to prevent exposure to the baby. The amount of radioactivity in the injection is very small, and virtually all activity is gone from the body within 2-3 days. Although it is extremely rare with bone scanning agents, a person may develop rash, swelling, or anaphylaxis.

Any time the body is penetrated (such as by a needle prick) there is a risk for infection. Injection into a vein also carries a slight risk for bleeding. The risk is no greater for a bone scan than for intravenous injection of any sort.

If a bone scan is being performed to evaluate possible fracture or infection, images will be performed shortly after the radiotracer injection, as well as after the 2-3 hour delay. This is called a three-phase bone scan.