The team of researchers from the Wellman Center for Photomedicine at Massachusetts General Hospital and Harvard Medical School said their device allows them to peer through the eyes of a mouse and monitor fluorescently labeled cells passing through its bloodstream.

"We could detect and count circulating cells continuously without drawing blood samples," said researcher Charles Lin. He and collaborator Irene Ghobrial of the Dana-Farber Cancer Institute said the new optical device might become a valuable tool because it allows scientists to test the effect of various experimental chemotherapy agents and therapeutic strategies in mice with multiple myeloma.

Researchers cautioned the new device is not designed for humans and has not been tested in clinical trials. As a laboratory tool, however, it will allow the team to observe what happens when different chemotherapy agents are given to rodents -- a standard early approach for evaluating the effectiveness of new chemotherapy agents and treatment strategies for humans.

The study is detailed in the journal Optics Letter.