Test Overview

A bone scan is a test to help find the cause of your back pain. It can be done to find damage to the bones, find cancer that has spread to the bones, and watch problems such as infection and trauma to the bones. A bone scan can often find a problem days to months earlier than a regular X-ray test.

For a bone scan, a radioactive substance is injected into a vein in your arm. This substance, called a tracer, travels through your bloodstream and into your bones. This could take several hours.

A special camera takes pictures of the tracer in your bones. Areas that absorb little or no amount of tracer appear as dark or "cold" spots. This could show a lack of blood supply to the bone or certain types of cancer.

Areas of fast bone growth or repair absorb more tracer and show up as bright or "hot" spots in the pictures. Hot spots may point to problems such as arthritis, a tumor, a fracture, or an infection.

Why It Is Done

A bone scan is done to:

• Find bone cancer or determine whether a cancer from another area, such as the breast, lung, kidney, thyroid gland, or prostate gland, has spread (metastasized) to the bone. See a picture of a bone scan showing the spread of cancer.
• Help diagnose the cause or location of unexplained bone pain, such as ongoing low back pain. A bone scan may be done first to help determine the location of an abnormal bone in complex bone structures such as the foot or spine. Follow-up evaluation then may be done with a computed tomography (CT) scan or magnetic resonance imaging (MRI).
• Help diagnose broken bones, such as a hip fracture or a stress fracture, not clearly seen on X-ray.
• Find damage to the bones caused by infection or other conditions, such as Paget's disease.

How To Prepare

Before the bone scan, tell your doctor if:

• You are or might be pregnant.
• You are breast-feeding. You will need to use formula (throw out your breast milk) for 1 to 2 days after the scan until the radioactive tracer is gone from your body.
• Within the past 4 days, you have had an X-ray test using barium contrast material (such as a barium enema) or have taken a medicine (such as Pepto-Bismol) that contains bismuth. Barium and bismuth can interfere with test results.

You may want to limit your fluids for up to 4 hours before the test, because you will be asked to drink extra fluids after the tracer is injected. You will empty your bladder right before the scan.

You probably will have to wait 1 to 3 hours after the tracer is injected before your bone scan is done. So you may want to bring something to read or a project to pass the time. For some types of bone scans, pictures are taken during the tracer injection, right afterward, and then 3 to 5 hours after the injection.

You may be asked to sign a consent form before the test. Talk to your doctor about any concerns or questions you have about the test.

To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

A bone scan is usually done by a nuclear medicine technologist. The scan pictures are usually interpreted by a radiologist or nuclear medicine specialist.

You will need to remove any jewelry that might get in the way of the scan. You may need to take off all or most of your clothes. You will be given a cloth or paper covering to use during the test.

Your arm will be cleaned where the tracer will be injected. A small amount of the tracer is injected.

It takes about 2 to 5 hours for the tracer to bind to your bone so that pictures can be taken with a special camera. During this time, you may be asked to drink 4 to 6 glasses of water so your body can wash out the tracer that does not collect in your bones. Just before the scan begins, you will probably be asked to empty your bladder to prevent any radioactive urine from blocking the view of your pelvic bones during the scan.

You will lie on your back on a table, and a large scanning camera will be above you. It may move slowly above and around your body, scanning for radiation released by the tracer and producing pictures. The camera does not produce any radiation.

You may be asked to move into different positions. You need to lie very still during each scan to avoid blurring the pictures.

A bone scan takes about 1 hour.

How It Feels

You may feel nothing at all from the needle when the tracer is injected, or you may feel a brief sting or pinch. The bone scan is usually painless. You may find it hard to remain still during the scan. Ask for a pillow or blanket to make yourself as comfortable as possible before the scan begins.

The test may be uncomfortable if you are having joint or bone pain. Try to relax by breathing slowly and deeply.

Risks

Allergic reactions to the tracer are rare. Your body will get rid of most of the tracer through your urine or stool within a day. Be sure to flush the toilet right away and thoroughly wash your hands with soap and water. The amount of radiation is so small that it is not a risk for people to come in contact with you after the test.

You may have some soreness or swelling where the needle went in. These symptoms can usually be relieved by applying moist, warm compresses to your arm.

There is always a slight risk of damage to cells or tissue from being exposed to any radiation, including the low level of radiation released by the tracer in this test.

Results

The results of a bone scan are usually available within 2 days.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Pregnancy. A bone scan is not usually done during pregnancy, because the radiation could damage the developing baby (fetus).
• Barium. If a bone scan is needed, it should be done before any tests that use barium (such as a barium enema).
• The inability to remain still during the test.
• A full bladder, which can block the view of the pelvic bones.

What To Think About

• A bone scan does not distinguish between normal and abnormal bone growth by itself. So bone scan results must be interpreted along with your symptoms and the results of X-ray tests. In addition, other tests such as a CT scan, an MRI, blood tests, or a biopsy may also be needed to further evaluate abnormal bone scan results.
• Some types of cancer or diseases cannot be identified on a bone scan.

References

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