A Better Imager for Identifying Tumors | Be Korea-savvy

A Better Imager for Identifying Tumors

Smaller, cheaper two-mode imaging system could help surgeons see and remove cancer (image: Optical Letters /BusinessWire)

Smaller, cheaper two-mode imaging system could help surgeons see and remove cancer (image: Optical Letters /BusinessWire)

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WASHINGTON, June 19, 2014 (Korea Bizwire)–Before they excise a tumor, surgeons need to determine exactly where the  cancerous cells lie. Now, research published today in The Optical  Society’s (OSA)  journal Optics  Letters details a new technique that could give surgeons cheaper  and more lightweight tools, such as goggles or hand-held devices, to  identify tumors in real time in the operating room.

The new technology, developed by a team at the University of Arizona and  Washington University in St. Louis, is a dual-mode imager that combines  two systems—near-infrared fluorescent imaging to detect marked cancer  cells and visible light reflectance imaging to see the contours of the  tissue itself—into one small, lightweight package approximately the size  of a quarter in diameter, just 25 millimeters across.

“Dual modality is the path forward because it has significant advantages  over single modality,” says author Rongguang Liang, associate professor  of optical sciences at the University of Arizona.

Interest in multi-modal imaging technology has surged over the last 10  years, says Optics Letters topical editor Brian Applegate of  Texas A&M University, who was not involved in the research. People have  realized that in order to better diagnose diseases like cancer, he says,  you need information from a variety of sources, whether it’s  fluorescence imaging, optical imaging or biochemical markers.

“By combining different modalities together, you get a much better  picture of the tissue,” which could help surgeons make sure they remove  every last bit of the tumor and as small amount of healthy tissue as  possible, Applegate says.

Currently, doctors can inject fluorescent dyes into a patient to help  them pinpoint cancer cells. The dyes converge onto the diseased cells,  and when doctors shine a light of a particular wavelength onto the  cancerous area, the dye glows. In the case of a common dye called  indocyanine green (ICG), it glows in near-infrared light. But because  the human eye isn’t sensitive to near-infrared light, surgeons have to  use a special camera to see the glow and identify the tumor’s precise  location.

Surgeons also need to be able to see the surface of the tissue and the  tumor underneath before cutting away, which requires visible light  imaging. So researchers have been developing systems that can see in  both fluorescent and visible light modes.

The trouble is that the two modes have opposing needs, which makes  integration difficult. Because the fluorescent glow tends to be dim, a  near-infrared light camera needs to have a wide aperture to collect as  much fluorescent light as possible. But a camera with a large aperture  has a low depth of field, which is the opposite of what’s needed for  visible-light imaging.

“The other solution is to put two different imaging systems together  side by side,” Liang says. “But that makes the device bulky, heavy and  not easy to use.”

To solve this problem, Liang’s group and that of his colleagues, Samuel  Achilefua and Viktor Gruev at Washington University in St. Louis,  created the first-of-its-kind dual-mode imaging system that doesn’t make  any sacrifices.

The new system relies on a simple aperture filter that consists of a  disk-shaped region in the middle and a ring-shaped area on the outside.  The middle area lets in visible and near-infrared light but the outer  ring only permits near-infrared light. When you place the filter in the  imaging system, the aperture is wide enough to let in plenty of  near-infrared light. But since visible light can’t penetrate the outer  ring, the visible-sensitive part of the filter has a small enough  aperture that the depth of field is large.

Liang’s team is now adapting its filter design for use in lightweight  goggle-like devices that a surgeon can wear while operating. They are  also developing a similar hand-held instrument.

Paper: “Dual-mode  optical imaging system for fluorescence image-guided surgery,” N.  Zhu et al., Optics Letters, vol. 39, issue 13, pp. 3830-3832  (2014)

EDITOR’S NOTE: Images are available to members of the media upon  request. Contact Lyndsay Meyer, lmeyer@osa.org.

About Optics Letters

Published by The Optical Society (OSA), Optics Letters offers  rapid dissemination of new results in all areas of optics with short,  original, peer-reviewed communications. Optics Letters covers the  latest research in optical science, including optical measurements,  optical components and devices, atmospheric optics, biomedical optics,  Fourier optics, integrated optics, optical processing, optoelectronics,  lasers, nonlinear optics, optical storage and holography, optical  coherence, polarization, quantum electronics, ultrafast optical  phenomena, photonic crystals, and fiber optics. This journal, edited by  Xi-Cheng Zhang of the University of Rochester and published twice each  month, is where readers look for the latest discoveries in optics. Visit www.OpticsInfoBase.org/OL.

About OSA

Founded in 1916, The Optical Society (OSA) is the leading professional  society for scientists, engineers, students and business leaders who  fuel discoveries, shape real-world applications and accelerate  achievements in the science of light. Through world-renowned  publications, meetings and membership programs, OSA provides quality  research, inspired interactions and dedicated resources for its  extensive global network of professionals in optics and photonics. For  more information, visit www.osa.org.

Source: OSA (via BusinessWire)

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