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Laboratory Testing

What does uptake mean in a bone scan?

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December 19, 2011 10:04PM

The term uptake, when used in connection with the imaging method called a bone scan, refers to the amount of radioactive material that is taken in (taken up - uptake) by the bones to facilitate the imaging.

To image bones this way, a radioactive chemical that "looks" like stuff that bones want to facilitate their health is injected into a patient. The bones see this material and start to collect it, and they end up gathering about half of it up (ball park figure). This causes the bones to "glow" with the emissions of the decaying radioactive material used in the procedure. An imaging system with a camera sensitive to the gamma rays is used to "look" at the bones and an image results.

The uptake of the tracer will be determined by how fast the metabolism of the bone is working. Faster metabolism will mean more uptake. Cancer, infection and a few other things cause a lot of uptake, and that is what makes them visible. They stand out as "hot spots" on the image.

The body metabolizes and dumps the radioactive material through the kidneys and urinary tract. You don't get any more radiation than a conventional X-ray gives you - probably quite a bit less.

The tracer, commonly 99mTc-Medronate (MDP), is a phosphate-based compound with technetium hooked in so the material will "glow" in the gamma ray spectrum and can be seen with equipment set up to look for electromagnetic radiation in those energy ranges. The nuclear medicine technologist can probably answer more questions for you, as can your physician.