HEMODYNAMICS/BIOMEDICAL IMAGING: Inexpensive off-the-shelf components enable hospital-grade blood-flow imaging

With less than $100 in off-the-shelf commercial parts, researchers at the University of Texas at Austin (UT-Austin) have duplicated the performance of expensive, scientific-grade laser-speckle contrast imaging (LSCI) instruments.

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With less than $100 in off-the-shelf commercial parts, researchers at the University of Texas at Austin (UT-Austin) have duplicated the performance of expensive, scientific-grade laser-speckle contrast imaging (LSCI) instruments. According to the authors of a paper describing the system, the work is a novel demonstration of the fact that it is possible to make a reliable blood-flow-imaging system solely with inexpensive parts.1

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Relative blood flow overlay from a two-camera in vivo experiment depicting the reduction in flow after stroke, over baseline speckle contrast images, with a 35% reduction of baseline cutoff for the CCD camera (a) and the webcam (b). Targeted area for photothrombosis is marked with a green circle in each image. Scale bars = 0.5 mm.

Measuring blood flow changes using LSCI requires a system totaling approximately $5,000: a laser light to illuminate the tissue, a camera to record the image, and focusing optics to direct the scattered light to the camera. In the UT-Austin approach, a $5 laser pointer is used to illuminate the tissue to be imaged, and the light reflected off the tissue is focused by a pair of generic 40 mm camera lenses onto the sensor—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 vs. low flow.

At just 5.6 cm in length and weighing only 25 g, 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, says biomedical engineer Andrew Dunn, an associate professor at UT-Austin and an author of the study. 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," said Dunn.

1. L. Richards et al., Biomed. Opt. Exp., 4, 10, 2269–2283 (2013).

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