Low-cost laser speckle contrast imaging of blood flow using a webcam

Abstract

Laser speckle contrast imaging has become a widely used tool for dynamic imaging of blood flow, both in animal models and in the clinic. Typically, laser speckle contrast imaging is performed using scientific-grade instrumentation. However, due to recent advances in camera technology, these expensive components may not be necessary to produce accurate images. In this paper, we demonstrate that a consumer-grade webcam can be used to visualize changes in flow, both in a microfluidic flow phantom and in vivo in a mouse model. A two-camera setup was used to simultaneously image with a high performance monochrome CCD camera and the webcam for direct comparison. The webcam was also tested with inexpensive aspheric lenses and a laser pointer for a complete low-cost, compact setup ($90, 5.6 cm length, 25 g). The CCD and webcam showed excellent agreement with the two-camera setup, and the inexpensive setup was used to image dynamic blood flow changes before and after a targeted cerebral occlusion.

Analysis of Laser Speckle Contrast Images Variability Using a Novel Empirical Mode Decomposition: Comparison of Results With Laser Doppler Flowmetry Signals Variability

“…Full-field laser Doppler imagers have been proposed in the last years but necessitate high-speed cameras ( [17], [18], [19], [20], [21], [22], [23], [24]). Very recently, laser speckle contrast imagers have been commercialized and have the advantage of being full-field and based on low cost devices, compared to other techniques ( [25], [26]). As for LDF, LSCI relies on the interaction of a laser light with the tissue under study.…”

“…2. Many works on instrumentation and processing of LSCI data are still proposed ( [26], [27], [28], [29]). Even if LSCI has the advantage of giving images with high temporal and spatial resolutions, LSCI data are not fully understood yet.…”

In vivo burn diagnosis by camera-phone diffuse reflectance laser speckle detection

“…While we used a large red laser and an industrial zoom lens in the current cameraphone dr-LSD system design, future instruments could employ compact laser diode modules and detachable camera-phone zoom lenses [13,20]. Moreover, handheld use of camera-phone dr-LSD devices might be achieved by implementing numerical image stabilization techniques [30] and fast speckle image processing on mobile phones.…”

“…In particular, we implement a spatiotemporal fluctuation analysis scheme based on the processing scheme proposed by Sadhwani et al [15] to extract the diameter of the speckle spot, and show that the retrieved diameter agrees well with the thickness of porcine burns of graded severity, enabling not only early discrimination of partial-thickness burns (within the first 24 hpb), but also longitudinal monitoring of the burn healing process (over 104 hpb). Unlike the system devised by Sadhwani et al and other instruments for diffuse reflectance laser speckle detection using scientific-or industrial-grade cameras [15][16][17][18], our apparatus takes advantage of advancements of miniature-camera technology in biomedical sciences [11,13,14,19,20] and employs a camera-phone for diffuse reflectance speckle detection. While the basic setup used here is similar to that of oblique incidence reflectometry (OIR) [21,22], we analyze spatial intensity variations in diffuse reflectance laser speckle patterns rather than OIR distances between the diffusion center and illumination entry point.…”

Multiscale Compression Entropy of Microvascular Blood FlowSignals: Comparison of Results from Laser Speckle Contrastand Laser Doppler Flowmetry Data in Healthy Subjects

“…LSCI leads to high temporal and spatial resolution images [15]. Moreover, laser speckle contrast imagers can be designed with low-cost devices [16]. In order to better understand LDF signals and to extract physiological information from the data, LDF time series have been the subject of many works, such as wavelet-based or entropy-based studies (see e.g., [17][18][19][20][21][22]).…”