Imaging technology lights way to early disease detection

17 Jun 2002

Purdue University researchers have developed a process called fluorescence lifetime imaging, a relatively inexpensive and painless technique that uses light to probe the biochemistry of tissues. The technique that may provide more specific information than traditional imaging technologies such as X-rays and magnetic resonance imaging (MRI), says Eva Sevick, associate professor of chemical engineering, in an upcoming paper in Applied Optics.

Fluorescence lifetime imaging relies on monitoring the light emitted, or fluoresced, by molecules after a harmless laser has illuminated a body part or tissue sample. Though it hasn't yet been tried on human tissue, Sevick says the technique shows great promise for detecting cancer, and could be used to determine whether a tumor is benign or malignant. While fluorescence imaging won't replace X-rays and MRIs, it might fill niches that other technologies can't, Sevick says. X-rays are used primarily to look at bones, teeth and other dense tissue, while MRIs look at the structure, and to a limited extent the biochemistry, of soft tissue.

In Sevick's laboratory, research associate Dilip Paithankar has spent two years determining how chemicals fluoresce and developing a computer program to generate simulated images of tissue based on fluorescence. A detector gathers the fluorescent light and the program tracks the time it takes for fluorescence to occur, which is the optical relaxation time or fluorescence lifetime. Based on the lifetime, the computer program generates an image which may, for example, show the metabolic state of the tissue, indicating disease is or isn't present; or map the chemical's concentration and distribution, indicating the boundaries of diseased tissue such as a tumor. The researchers recently filed a patent application for the program and for the use of fluorescence lifetime imaging in tissues.

Their next step will be to demonstrate the imaging technique using pet dogs that have developed breast cancer. The project, which also involves Dr. Dave Waters in Purdue's School of Veterinary Medicine, calls for optically imaging dog breast tissue in vivo before the cancerous tissue is removed and then comparing the images with the removed tissue.