Lee et al., Science

Tiny fluidic chips could speed the development of new medical imaging compounds.

Beating the Diagnostic Clock

Staff Writer

Researchers and clinicians who use radioactive tracers to pinpoint disease are in a race against time. The radioactivity in these compounds degrades so quickly, they can wink out of existence in a matter of minutes. Now scientists have developed a new type of chip that vastly speeds up the production of radioactive tracers, a development that could lead to an array of new compounds for detecting and treating disease.

The use of medical imaging techniques that use radioactive tracers has increased dramatically in recent years. In 2005, about 3 million clinical exams throughout the world were performed using one of these technologies--positron emission tomography (PET)--which can track everything from cancer in its earliest stages to Alzheimer's disease. But despite its resolution, PET is limited by the hours it can take researchers to synthesize and purify the radioactive compounds the technology relies on. By the time these compounds enter the body, they may have already exhausted much of their life, making extended analysis impossible.

To get around this problem, researchers led by Hsian-Rong Tseng at the University of California, Los Angeles, and Stephen Quake at Stanford University in California created a microfluidics chip capable of carrying out all the chemical reactions necessary for automatically synthesizing the most common PET probe called fluorodeoxyglucose (FDG). While microfluidics resemble standard microchips, they contain an array of channels, pumps, and valves for moving fluids around. In this case, those pieces were all controlled by a computer. And by automating the synthesis and speeding up the reactions by reducing the volume of chemicals used, the researchers were able to reduce the time needed to synthesize FDG 10-fold.

"I see it as a very enabling technology," says Victor Pike, a PET imaging expert at the National Institute of Mental Health in Bethesda, Maryland. In addition to making FDG cheaper and easier to produce, same technique could likely be used to automate the synthesis of a wide variety of other PET probes, Pike says. That could greatly expand the number of tracer compounds used in research, he says, which in turn may lead to benefits in treating a wide variety of diseases.

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