Probing for improved images

Researchers at the University of Wisconsin-Madison have developed a technology that can increase the chance for an accurate clinical diagnosis of breast cancer.

A new technology developed by Biomedical Engineering Assistant Professor Nimmi Ramanujam’s research group at the University of Wisconsin-Madison will be a “third eye” during breast biopsies and can increase the chance for an accurate clinical diagnosis of breast cancer.

Currently, doctors use X-ray or ultrasound – two-dimensional pictures – to guide the biopsy needle into a three-dimensional region. To ensure they biopsy 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 seven percent, or 70,000, of the women who have biopsies in the US. And another six percent of the women who have biopsies must undergo repeat procedures 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 fibre-optic probes that doctors can easily 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 limited sampling depth.

Initially, they used the probe to analyse healthy and cancerous tissue samples from patients who underwent surgery and identified cancerous tissue with 90-percent accuracy.

Now, with two grants totalling more than $1.2 million from the US National Cancer Institute and National Institute of Biomedical Imaging and Bioengineering, the group will test the probe during biopsies of about 250 patients. At the project’s end, the researchers will determine which light wavelength is best, or whether the optimum technology combines the two.

The fibre-optic probe will not eliminate the need for a biopsy, but rather increase the likelihood that doctors will take a sample from the correct site. And because of improved optical technology, they can potentially make diagnoses right away, says Ramanujam. Additionally, the probe can be made thin enough to fit through an even smaller needle than the standard quarter-inch size, making an emotionally draining procedure less physically traumatic.