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26 September 2013
Scientists Rig Hospital-grade Lightweight Blood Flow Imager on the Cheap
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Lyndsay Meyer
The Optical Society
+1.202.416.1435
lmeyer@osa.org
Scientists Rig Hospital-grade Lightweight Blood Flow Imager on the Cheap
New biological imaging system fifty times less expensive than standard equipment, suitable for imaging applications outside of the lab
A laser pointer (top right) illuminates a microfluidic flow phantom (bottom center) and the speckle pattern is imaged onto a webcam (top center) to enable calculation of flow images.
Credit: Andrew Dunn, University of Texas – Austin
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The webcam setup (right) is just about as effective as the more expensive CCD camera setup (left) at showing the reduction in blood flow following a stroke. The green circle shows the stroke’s affected area.
Credit: Andrew Dunn, University of Texas – Austin
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A speckle contrast image (right) of the stroke-affected section of mouse brain averaged over 10 frames, with an image depicting the vascular anatomy (left) for comparison.
Credit: Andrew Dunn, University of Texas – Austin
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“We demonstrate that the high cost of standard systems is unnecessary, because a system that costs $90 can give equivalent results for both in vitro and in vivo imaging applications,” said biomedical engineer Andrew Dunn, an associate professor and Dornberger Centennial Fellow in Engineering at UT-Austin and an author of the study.
Measuring blood flow changes using LSCI requires just a few parts – laser light to illuminate the tissue, a camera to record the image, and focusing optics to direct the scattered light to the camera – but at least one of them usually comes with a lofty price tag. The laser light reflects or scatters off the tissue and interferes with itself to create the speckle pattern collected by the camera. This speckle pattern provides a way to visualize the flow of blood within the tissue: areas with a high flow rate show up in the resulting image as blurrier speckles, which can be measured by their lower contrast. Together, all the parts can add up to as much as $5,000.
Unlike past attempts to create a cheaper speckle imager, the UT-Austin team’s new method uses only inexpensive pieces of equipment. A $5 laser pointer is used to illuminate the patch of tissue to be imaged. Light is reflected off the tissue and focused by a pair of generic 40-mm camera lenses onto the sensor of a $35 webcam. The team used their setup to image changes in blood flow in a mouse model and found that they were able to identify areas of high flow versus low flow.
At just 5.6 centimeters in length and weighing only 25 grams, the system is compact and lightweight, which would make it easier to transport for imaging applications outside of the lab, including clinics in areas with limited access to medical care, Dunn said.
Currently, the new system’s field of view, which is just a few square millimeters across, and resolution are limited by the size of the webcam sensor, but future versions could have a more flexible layout.
“The lens configuration could be easily adjusted to visualize even smaller structures by magnifying or to visualize larger structures by increasing the field of view, depending on what kind of flow the user is interested in visualizing,” Dunn said.
Paper: "Low-cost laser speckle contrast imaging of blood flow using a webcam," L. Richards et al., Biomedical Optics Express, Vol. 4, Issue 10, pp. 2269-2283 (2013).
EDITOR’S NOTE: Images are available to members of the media upon request. Contact Lyndsay Meyer, lmeyer@osa.org.
