Scientists say that a small tattoo placed on the heart could help them monitor new treatments, according to researchers at the Ohio State University.

The work looks at the idea of using stem cells to rebuild tissue damaged by a heart attack. As they study the theory, there have been problems monitoring progress.

But researcher Periannan Kuppusamy said tattooing tiny sensors onto the heart could keep track.

"They give a signal -- a magnetic resonance signal -- and this signal will give information about the oxygen concentration surrounding the crystal," he said.

In a recent study, it showed higher oxygen levels and better function after stem cells were transplanted into a damaged heart. The devices could also be used on transplanted organs to make sure they are functioning well. Kuppusamy said it could eventually be used to keep an eye on cancer treatments, too.

However, the devices have only been used in the lab, not in people.

In any situation, oxygen is essential to help the body heal.

The next step for researchers includes building a machine large enough for people that will read the data from the tattoo on the heart.