Imager May One Day Scan Moving Animals

NEWPORT NEWS, Va., July 11 (UPI) — A new biomedical imaging technique is being developed by government funded scientists that could one day let researchers conduct nuclear medicine imaging on small laboratory animals without restraining them or putting them under anesthesia. If successfully developed, the device could have major implications for human medicine.

Injecting animals with anesthesia is both dangerous to the animal and could suppress certain brain processes, said Drew Weisenberger, a staff scientist at the Thomas Jefferson National Accelerator Facility in Newport News, Va.

He is conducting a Department of Energy-funded study with researchers Dr. Michael Paulus of Oak Ridge National Laboratory in Oak Ridge, Tenn., Dr. Martin Pomper of Johns Hopkins University in Baltimore, Mary, and physicist Stan Majewski, also of JNAF.

The researchers had independently been working on projects involving computer tomography, which shows a three dimensional structure of a skeleton, as well as various devices for imaging small animals.

They decided to combine their work to develop a tool that would help molecular biologists study mice, an important animal model in the scientific world.

"Part of the problem with trying to image a mouse using nuclear medicine techniques is that you can't ask it stand still," Weisenberger said. "With PET scans, you can ask a human patient to hold still and do a brain scan."

Currently researchers must inject chemicals into mice to knock them out.

"But you can only do that so many times before you kill a mouse," Weisenberger said. Not only that, he said, but anesthesia can affect how the brain performs, which could influence the observations, and restraining the mouse causes stress.

The researchers plan to take anatomical and body function images of molecules labeled with radioisotopes while animals remain awake and "minimally restrained." An approach known as a Single Photon Emission Computer Tomography (SPECT) is used to take the images over certain time periods, recording the mouse's location in a small confined space. The system will also use X-ray computed tomography (CT) to record so-called body function images. That data will be synchronized with the animal's position and orientation over time.

If applied in human medicine, the technology, dubbed a motion correction technology, will help doctors take brain scans of patients who can't sit still, for example, due to tremors associated with Parkinson's disease.

The quest to develop the novel technology is fueled by a $1.3 million DOE grant and will draw on work being conducted at the University of Sydney and the Royal Prince Alfred Hospital in Sydney, Australia.

"The idea sounds innovative," said Dr. Robert Knight, professor of psychology and neurology at the University of California at Berkeley. "If they can actually do tomography in a free field, unrestrained — and it is not inconceivable [that this can be achieved] — then they have done a great deal. The value to human medicine, obviously, is that it will help the study of mice. And we know so much about the genome of mice that we are able to cause behavior changes that mimic human disease."