A bone scan is a medical imaging test to diagnose and evaluate bone diseases, injuries, infections, or tumors. It is a type of nuclear medicine imaging that uses a small amount of radioactive material, called a tracer, to detect abnormalities in bone metabolism.
During a bone scan, the tracer is injected into a vein in your arm and then allowed to circulate throughout your body. The tracer is absorbed by your bones and emits gamma rays which are detected by a specialized camera. Areas of increased bone activity appear as bright spots on the scan, which may indicate an area of injury, infection, or cancer.
Bone scans are often used to diagnose or monitor conditions such as osteoporosis, bone infections, bone tumors, and fractures that may not appear on traditional X-rays. They are generally safe and painless, although some people may experience mild discomfort during the injection of the tracer.
Why is the test performed?
A bone scan can be used for the following purposes:
- Determine whether you have a bone tumor or not.
- Assess whether a malignancy that started elsewhere in your body has progressed to your bones. Breast, lung, prostate, thyroid, and kidney cancers are common tumors that spread to the bones.
- When a fracture cannot be visible on a standard x-ray, it can be diagnosed (most commonly hip fractures, stress fractures in the feet or legs, or spine fractures) with the help of bone scan.
- Determine the cause of a bone infection (osteomyelitis).
- When no other cause of bone pain has been discovered, diagnose or ascertain the cause.
- Metabolic problems such as osteomalacia, primary hyperparathyroidism, osteoporosis, complicated regional pain syndrome, and Paget disease should be evaluated.
How is the test conducted?
In order to do a bone scan, a very little quantity of radioactive material (radiotracer) is injected into a vein. The chemical is carried by your blood to your bones and organs.
Images may be obtained quickly after the radioactive material is injected and again 3 to 4 hours later when it has gathered in the bones if a bone scan is performed to determine if you have a bone infection. This is known as a 3-phase bone scan.
Images are obtained only after a 3- to 4-hour wait to determine whether cancer has gone to the bone (metastatic bone disease).
The scanning portion of the exam will last around one hour. The camera on the scanner may move above and around you. You might need to switch positions.
You will most likely be urged to drink more water after receiving the radiotracer to prevent the substance from accumulating in your bladder.
How to prepare for this test?
Following are the steps to prepare for the bone scan test:
- Jewelry and other metal things must be removed. You could be required to wear a hospital gown.
- Inform your doctor if you are or suspect you are pregnant.
- Take no bismuth-containing medications, such as Pepto-Bismol, for four days before the test.
- Follow all the instructions properly which are given by the doctor.
What happens during the test?
A needle is inserted, and there might be some discomfort, but there is no discomfort throughout the scan. Throughout the scan, you must stay still. The technician will advise you when to switch positions.
You may feel some discomfort as a result of lying motionless for an extended length of time.
Understanding results
If the radiotracer is uniformly distributed throughout all of the bones, the test findings are deemed normal.
Compared to the neighboring bone, an aberrant scan will reveal "hot areas" and/or "cold spots." Hot spots are places with a high concentration of radioactive material. Cool patches are places that have absorbed fewer radioactive particles.
In addition to clinical information, bone scan data must be evaluated with other imaging investigations. Any abnormal results will be discussed with you by your physician.
Risks
If you are pregnant or breastfeeding, the test may be delayed to avoid exposing the infant to radiation.
If you must take the test while nursing, pump and discard the breast milk for the following two days.
The dose of radiation delivered into your vein is minute. During 2 to 3 days, the body is free of all radiation. The radiotracer used exposes you to very low levels of radiation. The danger is probably comparable to that of normal x-rays.
The following risks are associated with the bone radiotracer:
- Anaphylaxis (severe allergic response)
- Rash
- Swelling
