What is a bone scan?
A bone scan is an imaging test used to help diagnose problems with your bones. Safely use a very small amount of a radioactive drug called a radiopharmaceutical. It has also been referred to as “dye,” but it does not stain tissues. Specifically, a bone scan is performed to screen for problems with bone metabolism. Bone metabolism refers to the process in which bone breaks down and rebuilds itself.
New bone is part of the healing process when the bone is injured or broken. A bone scan is a good way to view and document abnormal metabolic activity in the bones. A bone scan may also be used to determine whether cancer has spread to the bones from another area of the body, such as the prostate or breast.
During a bone scan, a radioactive substance is injected into a vein that your bone takes. You will then be monitored for several hours. A very small amount of radiation is used in the material, and almost all of it is released from your body within two or three days.
Why a bone scan is done?
If you have unexplained bone pain, a bone scan may help determine the cause. The test is very sensitive to any difference in bone metabolism. The ability to scan the entire skeleton makes the bone scan very helpful in diagnosing a wide range of bone disorders, including:
- Paget’s disease of bone
- Cancer that originates in the bones
- Cancer that has spread to the bone from a different site
- Arthritis or joint or bone replacement (osteomyelitis)
- Impaired blood flow to the bone or death of bone tissue (avascular necrosis)
Risk factors of bone scan
Although the test relies on radiotracers to produce images, these reagents produce very little radiation exposure – less than a CT scan.
Preparation for a bone scan
When you schedule an orthopedic scan, the hospital or imaging center staff will tell you how to prepare. Usually, you don’t need a lot of special preparations before a bone scan, but it is important to confirm this from the location where the test will be performed. If there is anything unclear in the instructions, speak with your health care team. Here are some things to expect:
- Your usual medications: Tell your health care team about all the medicines you take, including over-the-counter (OTC) medicines and supplements. Medicines containing barium or bismuth can affect test results. Your doctor may ask you not to take it before the test.
- Personal medical history: Inform the staff if you have any allergies to any medication or medical condition. Women should tell their health care team if they are breastfeeding or may be pregnant.
- What to wear: Before the test, you will need to remove metallic objects, such as jewellery. You may also need to wear a hospital gown.
- Insurance, costs, and approval: If you are concerned about bone scan costs, contact your insurance provider before the scan. Ask if the test is covered and what, if any, you will pay. The hospital or center staff will ask you to sign a consent form upon your arrival for the examination. This form demonstrates that you understand the risks and benefits of the test. The form also states that you agree to take the test. If you have concerns, talk to your doctor before signing up.
What happens during a bone scan?
The bone scan can be done on an outpatient basis or as part of your hospital stay. Procedures may vary depending on your condition and your doctor’s practices.
Generally, a bone scan follows this process:
- An intravenous (IV) line will be started in the hand or arm to inject the reagent.
- The reagent will be injected into a vein. The tracer will be allowed to focus on the bone tissue for one to three hours. You may be permitted to walk around or even leave the facility during this time. You will not be dangerous to other people, as the tracking device emits less radiation than a standard x-ray.
- During the waiting period, you will need to drink several cups of water (four to six cups) to help flush out any tracer that is not concentrated in the bone tissue.
- If a bone scan is performed to detect bone infection, a set of scans can be performed immediately after injection of the tracer. Another set of scans will be done after the tracer is allowed to focus on the bone tissue.
- When the tracer is allowed to concentrate in the bone tissue for an appropriate period of time, you will be asked to empty your bladder before the scan begins. A full bladder can deform the bones of the pelvis and may become uncomfortable during the examination, which may take up to an hour to complete.
- You will be asked to lie flat on the scanning table, as any movement may affect the quality of the scan.
- The scanner will slowly move over you several times as it detects the gamma rays emitted by the tracking device in the bone tissue.
- Your position may be changed during the scan to obtain specific views of the bones.
- When the scan is complete, the fourth streak will be removed.
While the bone scan itself does not cause any pain, having to lie still for the duration of the procedure may cause some discomfort or pain, especially in the case of a recent injury or a surgical procedure such as surgery. The technician will use all possible comfort measures and complete the procedure as quickly as possible to reduce any discomfort or pain.
What should I expect after a bone scan?
Bone scans generally do not cause any after-effects. Through the natural radioactive decay process, a small amount of the radioactive chemical in your body will lose its radioactivity over time. It is also excreted from your body in the urine for about 24 hours. You may be asked to take special precautions after urinating, flush the toilet twice, and wash your hands well.
It is advised that you drink plenty of water for the day after the scan to help flush radionuclides from your system. If you have been in contact with children or pregnant women, you should let your doctor know. Although the radiation levels used in the scan are small, special precautions may be advised. Your hospital should give you more advice about this.