ARLINGTON, Va., Sept. 5, 2003 -- Researchers have removed some of the fogginess from PET images with a new scanner that is eight times sharper than before. This opens the way for more precise studies of disease in mice and men.

The device makes clearer, more detailed images of rats and mice that model human illnesses. This allows the animals to be observed noninvasively over time to study normal development, the onset of disease, and the effectiveness of treatments, all in the same animal so fewer are needed for research.

MicroPET II, developed by Whitaker investigator Simon Cherry, Ph.D., of the University of California, Davis, and his colleagues, represents an eight-fold increase in resolution over the prototype's predecessor.

"We think it's the highest resolution scanner in existence," Cherry said. The device can resolve a volume of about one cubic millimeter, or one microliter.

"The quality of the scientific information may be improved, and it may also reduce the overall time and cost of animal studies," said Cherry, whose group reported its results in the June 7 issue of Physics in Medicine and Biology and presented the work last month to the Society for Molecular Imaging in San Francisco.

More than 5,000 studies have been performed using MicroPET II's predecessor, MicroPET®, now marketed by Concorde Microsystems of Tennessee, where Cherry is a consultant. More than 50 institutions and companies are using the system in one of the fastest growing areas of PET (Positron Emission Tomography) imaging.

PET is sensitive to short-lived radioactive atoms that emit positrons, positively charged atomic particles. These atoms can be attached to other molecules to create radiotracers that bind to specific cell types or are involved in specific processes. Cancer cells, for example, which consume high levels of glucose, can be tagged with a radioactive version of glucose.

Mice play an increasingly important role as models for understanding and treating human disease, enhanced by the recent completion of both the mouse and human genome maps. Mice share about 95 percent of their genes with humans.

"The models are getting increasingly sophisticated and realistic," Cherry said. "Imaging provides a way to track the development of the disease and to evaluate new therapeutic approaches in intact, living animals and follow time courses within individual animals."

PET acts as a window into living biology, tracking a range of biological processes from metabolism to receptors, gene expression, drug activity and others.

Cherry's group has begun using MicroPET II in mouse studies of prostate cancer, breast cancer, and heart (movie 512kb) function. They are working with a drug company weighing the effects of new anti-cancer agents by detecting tumor response to drugs within the first 48 hours.

"We can also label the drug itself and follow its biodistribution, concentration at the target site, etc.," Cherry said. "This is all critical information in drug development and dosing. MicroPET provides an efficient and accurate way of doing this." Because PET can also be done in humans, the same experiments can be repeated in clinical volunteers.

Cherry's research group includes Yuan-Chuan Tai of Washington University in St. Louis; Arion Chatziioannou, Robert Silverman and Ken Meadors of the University of California, Los Angeles; Stefan Siegel and Danny Newport of Concorde Microsystems; and Yongfeng Yang and Jennifer Stickel of UC Davis.

Cherry's work on micro-PET systems began in 1993 under a Biomedical Engineering Research Grant from The Whitaker Foundation.

Contact:
Frank Blanchard (703) 528-2430
Simon Cherry (530) 754-9419