Positron emission tomography or PET imaging is widely used to detect and follow cancer in human patients. Now UC Davis researchers have come up with a micro-PET machine that can do the same in animals as small as a mouse.

Simon Cherry, a professor of biomedical engineering at UC Davis, led the micro-PET effort. Craig Abbey, also in the Department of Biomedical Engineering, designed image analysis methods to go along with it.

A first research target for the new machine: A mouse model of ductal carcinoma in situ, or DCIS, a precursor to breast cancer in humans. Using the micro-PET, cancer researchers Alexander Borowsky, Robert Cardiff and Jeffrey Gregg, all at the UC Davis Center for Comparative Medicine, are able to non-invasively follow the natural growth of the DCIS-like lesions in mice over a long period of time.

Such investigation is impossible in human patients, because the standard of care is to remove DCIS tissue. Most invasive breast cancers are thought to develop from DCIS.

"Not only can we see the DCIS-like lesion in the mouse, but we can detect its earliest transition to an invasive tumor," Borowsky says.

The next step: using Cherry's micro-PET to assess treatments aimed at slowing or stopping that transition. The UC Davis research was published July 26 in the Proceedings of the National Academy of Sciences.