Scientists Pioneer Imaging Technique

Researchers at Harvard have pioneered a chemical process that enhances the ability of a radioactive fluorine isotope to bond with organic molecules, paving the way for improved medical imaging and pharmaceutical drug production.

The work began in 2008, when a team of scientists led by Associate Professor of Chemistry and Chemical Biology Tobias Ritter attempted to improve the tracking of small, complex molecules in the body.

Ritter investigated Positron Emission Tomography (PET), an imaging technique that utilizes tracers injected into the body—such as the fluorine-18 isotope—to create three-dimensional images of internal organs.

Ritter said he set out to address the largest challenge with PET: getting the isotope fluorine-18 to bond with organic molecules, which are carbon-based.

“What we now have is a general and mild way to make carbon-fluorine bonds with biologically interesting molecules,” said Daniel C. Choi ’08, who worked in Ritter’s lab as an undergraduate. “This will expand the power of PET.”

Ritter’s team also discovered a way to overcome fluorine’s extremely short half-life by introducing the fluorine into the injectable compound late in the compound’s synthesis.

This process allows researchers to maximize the use of fluorine as a PET tracer.

The researchers say these findings hold great pharmaceutical and clinical promise.

“The innovation is in chemistry but the application is in imaging,” Ritter said.

Companies hoping to test the effectiveness of newly developed drugs, for example, can leverage the increased effectiveness of PET to determine whether the drugs can reach their target location.

This type of screening could potentially lead to the more effective use of pharmaceutical development resources.

Though more research needs to be conducted to ensure the reliability of the process, the researchers say they are optimistic about what these findings can do for imaging.

Choi added that he was struck by not only the usefulness of the new chemical process, but also its elegance.

“It’s beautiful in the way that only nature can make it,” he said.