Techniques

According to Medline Plus, patients who undergo a CAT scan lie on a table which slides into a circular machine that takes three-dimensional images of the body. Bone scans require the patient to be injected with a radioactive material, which is then traced through the blood stream while a special camera records how much of the material is absorbed by the bones.

Reasons for the Scans

Staff members at the Mayo Clinic say CAT scans are done to diagnose muscle and bone disorders, locate a tumor, blood clot, or infection, and look for cancer or heart disease. CAT scans can also be used to guide doctors during a biopsy. Doctors use bone scans to detect fractures, arthritis, bone cancer or infections in the joints.

Risks

Medline Plus says reactions to the bone tracer material in a bone scan are rare but may include a severe allergic reaction, swelling or rash. Risks for a CAT scan include a slight risk for cancer and an allergic reaction to the contrast solution if one is given.

What to Expect

Patients must lie completely still during both types of scans, but not all patients who undergo a CAT scan will have to be injected with a contrast solution. The injection for a bone scan involves a needle prick, while CAT contrast solution is either taken orally, delivered through an IV, or given rectally as an enema.

Images

CAT scans take three-dimensional images of the body, showing everything in slices after the scan is complete. Bone scans are flat images which show dark areas of the bones that indicate where the problem is and give the doctor a clue about what's wrong.

Source:

Medline Plus - Bone Scan

Medline Plus - CT Scan

Radiology Info

More Information:

CAT Scan Images

Bone Scan Images