The light stuff

A few years back I made a bet that molecular imaging would become nothing more than a synonym for nuclear medicine. At the time it made sense, what with companies parking their gamma cameras and PET/CTs under this title. But since then, you might say I've seen the light.

Optical imaging, it seems, is going to blow that cynicism apart.

Recent progress in this area of technology, reported in DI SCAN leads me to believe that optical imaging may become a driving force in molecular imaging.

Optical tomography gains ground as research tool, 11/07/05

Nanotechnology initiative establishes centers of excellence at major universities, 10/10/05

The chance of this happening is underscored by the collaboration between Philips and Schering, announced at the RSNA meeting, on the development of an optical tomography device for imaging the breast.

The two companies plan to combine a fluorescent dye, omocianine, developed by Schering, and a prototypical optical tomography scanner now in development at Philips. The dye is to be injected into the bloodstream, absorbing energy from a pulsed laser built into the Philips device. The dye will then fluoresce, transmitting light back to the scanner for reconstruction into images. Abnormal vascular beds apparent in the images will indicate tumors.

A commercial device is years away, as the safety and efficacy of the device and imaging agent must be documented to win FDA approval for marketing in the U.S. Clinical trials planned for next year will begin to provide that documentation.

Results presented Dec. 8 at the San Antonio Breast Cancer Symposium described the development of tiny particles, called nanoshells, that can be tuned to scatter or absorb light. When fashioned with relatively thin shells, they reflect light, improving the visualization of breast cancer, according to researchers from Rice University. When outfitted with thick shells, they heat up, potentially killing the cancer.

Gold nanoshells, which respond to near-infrared light, appear to accumulate in tumors, especially when they are coated with tumor-specific antibodies. Once there, they can be used to treat the tumor with heat or, when designed to scatter light, enhance optical imaging.

So it may be that molecular imaging comes into the clinical consciousness not over the well-worn paths of nuclear medicine but through a "window" traversed by light. It would be a great irony if optical imaging, whose use in arthroscopy, endoscopy, and lately colonoscopy has been associated with old school medicine, led the way to radical diagnostic changes in the early 21st century.