Biomedical Engineering Department, University of Texas at Austin
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Ponticorvo, A., Dunn, A. K. How to Build a Laser Speckle Contrast Imaging (LSCI) System to Monitor Blood Flow. J. Vis. Exp. (45), e2004, doi:10.3791/2004 (2010).
Laser Speckle Contrast Imaging (LSCI) is a simple yet powerful technique that is used for full-field imaging of blood flow. The technique analyzes fluctuations in a dynamic speckle pattern to detect the movement of particles similar to how laser Doppler analyzes frequency shifts to determine particle speed. Because it can be used to monitor the movement of red blood cells, LSCI has become a popular tool for measuring blood flow in tissues such as the retina, skin, and brain. It has become especially useful in neuroscience where blood flow changes during physiological events like functional activation, stroke, and spreading depolarization can be quantified. LSCI is also attractive because it provides excellent spatial and temporal resolution while using inexpensive instrumentation that can easily be combined with other imaging modalities. Here we show how to build a LSCI setup and demonstrate its ability to monitor blood flow changes in the brain during an animal experiment.
1. Imaging Setup
2. Surgical Preparation
3. Collecting Data
4. Representative Results
Figure 1 shows an example of a typical raw speckle image and a converted speckle contrast image that should be generated when using the software to examine blood flow in the brain. For visualizing changes in blood flow, it is easier to have the software generate relative maps of blood flow. Figure 2 shows a typical series of relative blood flow images during a transient increase in blood flow that travels across the field of view. The red color represents an increase in blood flow while the blue color shows a decrease. The green color indicates that there is no change in blood flow relative to a given baseline.
Figure 1. Example of a raw speckle image (left) and speckle contrast image (right).
Figure 2. Example of several relative blood flow images at different time points during a transient increase in blood flow followed by a decrease in blood flow.
In this video we have demonstrated how easy it is to build and use a laser speckle contrast imaging (LSCI) system to look at changes in blood flow. LSCI was developed in the 1980s as a way to generate maps of blood flow in the retina1. While still used to image the retina and skin perfusion, it has become extremely popular as a technique to image blood flow in the brain2. This is largely due to the excellent spatial and temporal resolution provided and the simplicity of the instrumentation. LSCI has been used to investigate changes in blood flow due to functional activation3,4, cortical spreading depression5, and stroke6,7. It also has the advantage of easily combining with other techniques like reflectance imaging8, voltage sensitive dyes9, or oxygen probes10,11 so that multiple physiological parameters can be imaged simultaneously.
No conflicts of interest declared.
The authors acknowledge support from the American Heart Association (0735136N), Dana Foundation, National Science Foundation (CBET/0737731), and the Coulter Foundation.
|Macro zoom lens||Edmund Scientific||NT58-240|
|Laser diode||Thorlabs Inc.||HL6501MG|
|Laser diode controller||Thorlabs Inc.||LDC201CU|
The technique is versatile enough to be used with a wide range of equipment. The only things necessary to perform the experiment are a compatible camera with a lens, a laser diode of any type with a controller, and the provided software. A table of the specific equipment used in the video is included above.
A complete list of additional parts that can be used in this experiment is found on our website, http://bach.bme.utexas.edu/mediawiki/index.php/Hardware