Better Bioimaging with a Liquid Lens

A new handheld probe uses near-infrared light and a liquid lens to create sharp three-dimensional images of lesions beneath the skin, in a few seconds. The device, created by Jannick Rolland of the University of Rochester, allows doctors to peer two millimeters below the skin's surface to see, in particular, whether the cells beneath a mole show signs of being cancerous. If proved reliable, the probe could sharply reduce the number of biopsies that are necessary.

The screwdriver-sized probe has a resolution of two microns, sufficient to see if the nuclei of cells are enlarged—a potential indicator of cancer. The device creates a 3-D image using an oil-water composite liquid lens. Applying a small amount of electricity to the lens causes it to change shape, and doing so repeatedly captures a wide range of focal distances.
One of the problems with imaging the skin is getting a high-resolution picture quickly, says Rolland. The system takes thousands of pictures, refocusing every 30 milliseconds at a different depth. An algorithm stitches the images together into a coherent 3-D whole. Rolland says the probe is now being tested in clinics and would be inexpensive to manufacture.
A doctor, she explains, will press against a suspicious-looking mole, and within minutes, it will give him or her a good idea whether a biopsy is necessary. The doctor will be able to see images way down to the level of the cell.  Rolland presented some of her findings at the American Association for the Advancement of Science meeting in Washington, D.C., last week.
Rolland has been discussing possible collaborations with eye doctors who want to take a close look at living tissue in the cornea, and with researchers who want to see how the skin acts as a barrier for pathogens. Already her technique is being combined with Doppler ultrasound to study the flow of blood through vessels beneath the skin.
"The ultimate challenge is demonstrating the ability of any novel device to discriminate between cancerous and noncancerous lesions that appear visibly similar to the trained eye of clinician," says Chetan Patil, a research associate at Vanderbilt University's Biomedical Photonics Laboratories. He adds, however, that a large amount of data is required to demonstrate the utility of any device. 
Imaging beneath the skin has long been a challenge. "Skin tissue scatters the light strongly, so the signal to be detected is small compared to the noise," says Ibrahim Abdulhalim, who works on biomedical optical engineering devices at Israel's Ben Gurion University. He adds that researchers are always looking for new techniques to improve the quality of imaging information.
Rolland is optimistic about new imaging possibilities. She says, "For me, it's neat to see how advances in instrumentation can really enable new science. It's not just engineering."

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