An article in Technology Review takes a closer look at the nascent field of molecular imaging. Scientists at the NCI and the University of Tokyo designed a pH-sensitive fluorescent probe to seek out and grab on to specific receptors on a tumor's surface and light up only when the probe has made it inside a cancer cell. They tested the probe on HER2-positive tumors in mice and found that the probe detected tumors with 99 percent accuracy compared to an "always on" probe, which only detected 85 percent of the tumors. "This specific system may have limited application, especially in regards to taking this forward into the clinic," says Scott Hilderbrand, a scientist at Massachusetts General Hospital's Center for Molecular Imaging Research. "But the concept and approach are definitely very relevant towards the area of enhanced tumor detection at the molecular level."