Test Overview

A bone scan is a
test that can 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.

During a bone scan, a
radioactive substance called a tracer is injected into a vein
in your arm. The tracer travels through your bloodstream and into your bones. Then 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 cancer
    from another area, such as the breast, lung, kidney,
    thyroid gland, or
    prostate gland, has spread (metastasized) to the bone.
  • 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 breastfeeding. The radioactive tracer used in this test can get into your breast milk. Do not breastfeed your baby for 1 or 2 days after this test. During this time, you can give your baby breast milk you stored before the test, or you can give formula. Discard the breast milk you pump in the 1 or 2 days after the test.
  • 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 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.

Talk to your doctor about any concerns you have regarding the
need for the test, its risks, how it will be done, or what the results will
mean. 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 a table, with a
large scanning camera above you. It may move slowly
above, below, 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 very 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.

Bone scan
Normal:

The radioactive tracer is
evenly spread among the bones. No areas of too much or too little tracer
are seen.

Abnormal:

The tracer has accumulated in
certain areas of the bone, indicating one or more “hot” spots. Hot spots may be
caused by a fracture that is healing, bone cancer, a bone infection (osteomyelitis),
arthritis, or a disease of abnormal bone
metabolism (such as
Paget’s disease).

Certain areas of the bone lack the presence of tracer, indicating one or more “cold” spots. Cold spots
may be caused by a certain type of cancer (such as
multiple myeloma) or lack of blood supply to the bone
(bone infarction).

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

Other Works Consulted

  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
  • Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.

Credits

ByHealthwise Staff
Primary Medical Reviewer Anne C. Poinier, MD – Internal Medicine
Specialist Medical Reviewer Myo Min Han, MD – Nuclear Medicine

Current as ofOctober 9, 2017