Bone Scan


Introduction

After cancer has been diagnosed elsewhere in the body, doctors may recommend a bone scan to determine whether the disease has spread to the bone. Also called bone scintigraphy, this scan is a type of x–ray performed after a small amount of radioactive substance is injected into a vein. The radioactive substance concentrates in bone abnormalities such as cancer, infections or even fractures. Although the scan itself takes about an hour, the radioactive material must be injected several hours in advance. Other than the slight discomfort of the injection, bone scans are painless. The only danger is a very slight risk of an allergic reaction to the radioactive material which is eliminated from the body within a day. Bone scans are usually done as an out–patient procedure in a radiology or nuclear medicine department of a hospital.

Procedure
  • A tracer, or bone–seeking nuclide, is injected into a vein.
  • The tracer emits gamma radiation, which is detected by the scanner.
  • When the tracer has collected in the bones (about 2 to 4 hours) after the injection, the scan is performed.
  • The distribution of gamma rays is recorded by the scanner, and the information is recorded in a computer.
  • The image then appears on the computer screen.
  • Normal or even distribution areas appear gray.
  • “Hot spots” are areas where there is an increased absorption of the tracer; these appear dark. “Cold spots” are areas where there is less absorption of the tracer.
  • These appear light. The scanning part of the test will last about 1 hour and may require changing to various positions.
  • You must remove dentures, jewelry or other metal objects.
  • You will have to wear a hospital gown.
  • There is a bit of pain when the needle is inserted.
  • Later the injection site may be tender to the touch.
  • You must remain still during the scan, and you will be instructed when to change positions.
Indications
  • Detecting areas of abnormal bone metabolism.
  • Lesions.
  • Fractures.
  • Degenerative disorders.
  • Cancer.
  • Infection.
Risks
  • If the patient is pregnant or nursing a baby, the test may be postponed to decrease the chance of affecting the baby.
  • A person with a hypersensitive reaction may develop a rash, swelling, or other allergic side effects.