Doctors currently use X-ray or ultrasound - two-dimensional pictures - to guide the biopsy needle into a three-dimensional region. To ensure that they are doing the biopsy at the right spot, they take up to a dozen tissue samples.

"If you're in the wrong spot and you don't get the cancer, then you're basically concluding that this woman doesn't have a disease that needs to be treated," says Ramanujam.

She says missed diagnoses occur in about 7 percent, or 70,000, of the women who have biopsies. An additional 6 percent of the women who have biopsies must have the procedures repeated because the results are inconclusive.

Ramanujam and graduate students Carmalyn Lubawy and Changfang Zhu are harnessing the power of light to add another dimension of information about the tissue properties at the needle tip. Light can provide structural information such as cell or nuclear size, as well as measurements of hemoglobin oxygenation, vascularity and cellular metabolic rate - all of which are hallmarks of carcinogenesis and can indicate whether the needle has hit the mark, she says.

"These chemical and structural features are intrinsic inside tissue," she says. "They're not things you have to add, so you don't have to add any dyes to make it work."

Her group has built fiber-optic probes that doctors easily can thread down the existing hollow biopsy needle to the tip to help them find the right area to sample. The researchers are testing probes in both the near-infrared wavelength, which allows light to go deeper but probes fewer molecules, and UV-visible wavelength range, which allows them to probe a large number of molecules but with lim
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6-Jul-2004