A bone scan, also known as a scintigraphy, is a nuclear imaging test that evaluates bone cell function. According to MedlinePlus, a service of the National Institutes of Health, a bone scan involves injecting a radioactive material, called radiotracer, into a vein. The radiotracer travels through the blood and into the bones and organs where it gives off radiation. This radiation is then detected by a camera that scans the body.
Use
A bone scan is a helpful tool used to evaluate unexplained bone pain or to detect cancer, leukemia, lymphoma, tumors, fractures, arthritis, bone infection and metabolic disorders of the bone such as osetomalacia, renal osteodystrophy, primary hyperparathyroidism, Paget's disease, complex regional pain syndrome and osteoporosis.
Testing Procedures
Testing and time needed for the test vary. If a bone infection is suspected, a three-phase bone scan is performed. In this test, the body may be scanned shortly after the injection of the radiotracer and then again three to four hours later when it has collected in the bones, according to MedlinePlus. To evaluate other bone disorders, images are usually taken between two to four hours after the injection. After receiving the radiotracer, it is important to drink at least 8 oz. of liquid to help eliminate excess radiotracer from the body.
After the radiotracer has been absorbed, the patient will be asked to lie down on a special bed. This bed slides as the cameras recording images pass above and below the bed. The patient must lie perfectly still, as any movement can destroy the image. After the scan is complete, normal daily activities may resume.
Normal Results
Bone scan results are considered normal if the radiotracer has been evenly distributed throughout all of the bones in the body.
Abnormal Results
Abnormal results show increased or decreased distribution of the radioactive material in certain parts of the body. "Hot spots" may be seen where the radiotracer has accumulated. This may occur in areas of rapid bone growth and repair or could indicate arthritis or the presence of a tumor, a fracture or an infection, according to Brigham and Women's Hospital. "Cold spots" are areas that show less of the radiotracer, which may be due to a lack of blood supply to the bone or to the presence of certain types of cancer.
Diagnosis
The MayoClinic.com states that a bone scan is very sensitive to bone irregularity; however, it does not give the exact cause for the abnormality. A thorough medical history along with additional tests such as computerized tomography, magnetic imaging or a biopsy may be needed to make a definite diagnosis.
Risks
According to the "New York Times," the amount of injected radiation is minimal, and is out of the body's system within 2-3 days. If an individual is pregnant the test may be rescheduled to prevent exposure to the developing baby. If breastfeeding, milk should be pumped and discarded for two days following the procedure. (See References 5)
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