A bone scan is a diagnostic test that uses nuclear imaging to determine several forms of the bone disorder. Nuclear imaging entails using minimal amounts of radioactive elements (radiotracers), a special camera that can identify radioactivity, and a computer to see structures of the bones inside the system.

The tracer is absorbed by cells and tissues that are altering. Thus, a bone scan can be used to find the source of unexplained skeletal pain, bone infection, or injury that cannot be observed on a regular X-ray. In addition, a bone scan serves as a vital tool for determining cancer that has metastasized to the bone from the tumour’s original place like breast or prostate cancer.

Purpose Of The Test

A bone scan may help the doctor to evaluate the reason for sudden bone pain. The scan is sensitive to differences in bone metabolism, which show up in the body by the radioactive tracer. Scanning the entire skeletal system assists in diagnosing a host of bone disorders such as:

• Fractures
• Arthritis
• Paget's disease of bone
• Cancer developing in the bone
• Cancer that has metastasized to bone from a different location
• Infection of the joints, joint replacements, or bones

Also Read: Bone Cancer: Causes, Symptoms And Treatment

How To Prepare For The Test?

You do not require any specific dietary restrictions or restricted activities before a bone scan. Inform your doctor if you’re taking any medication containing bismuth like Pepto-Bismol or if you have had an X-ray done using barium contrast material within the last four days. As barium and bismuth can intervene with bone scan results.

You may be asked to wear loose clothing without any accessories or jewellery. During the scan, you would be asked to wear a gown provided by the scan centre.

Also, bone scans are not done on pregnant or lactating women, as concerns about radiation exposure to the baby. Hence it is important to inform your doctor if you’re pregnant or think you may be pregnant or if you’re lactating.

What To Expect?

This scan involves both an injection and the actual scan.

The Injection

Small amounts of radioactive materials are injected into a vein in the hand or arm. The time duration between the injection and scan differs, based on the reason for the scan.

A few images are captured after the injection, however, the main pictures are taken 2 to 4 hours later to let the radioactive element circulate and be absorbed by the bones. You may be asked to drink plenty of water while waiting for the scan to be completed. Also asked to empty the bladder before the scan to eliminate any unabsorbed tracer from the system.

The Scan

You would be asked to lie on a table, while arm-like equipment supporting a tracer-sensitive camera passes back and for over the system. The entire scan takes about an hour to complete, and it is a pain-free test.

The doctor may order a three-phase bone scan, which comprises a set of images taken at different times. A number of images are taken as the element is injected, then sometime after the injection, and again 3 to 5 hours after the injection.

To evaluate and assess some of the bones in the system, the healthcare provider may recommend additional imaging called single-photon computerized tomography(SPECT). This imaging test can help to identify diseases that are very deep in the bone or places that are too hard to see. During SPECT scan, the camera captures pictures as it rotates around the body.

Also Read: Bone Density Test: Procedure, Risks, Results

After The Test

A bone scan usually has no side effects. The doctor may advise you to drink plenty of fluids for the next two days to flush out any traces of radioactive elements from the body. The radioactivity from the trace element is completely eliminated within two days after the scan.

Results

The radiologist will look for any evidence of unusual bone metabolism on the scans, which appear as darker “hot spots” and lighter “cold spots” where the tracers have accumulated or not. Though a bone scan is sensitive to differences in bone metabolism, it’s less valuable in assessing the cause of the differences. Also, if your bone scan results show hot spots then you may need more tests to identify the cause.