Handheld motion stabilized laser speckle imaging

Ben Lertsakdadet; Cody Dunn; Adrian Bahani; Christian Crouzet; Bernard Choi

doi:10.1364/BOE.10.005149

Handheld motion stabilized laser speckle imaging

Biomed Opt Express. 2019 Sep 13;10(10):5149-5158. doi: 10.1364/BOE.10.005149. eCollection 2019 Oct 1.

Authors

Ben Lertsakdadet^{1

2}, Cody Dunn^{1

2

3}, Adrian Bahani^{1

2}, Christian Crouzet^{1

2}, Bernard Choi^{1

2

3

4}

Affiliations

¹ Beckman Laser Institute and Medical Clinic, University of California-Irvine, 1002 Health Sciences Road East, Irvine, CA 92612, USA.
² Department of Biomedical Engineering, University of California, Irvine, 3120 Natural Sciences II, Irvine, CA 92697, USA.
³ Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2400 Engineering Hall, Irvine, CA 92697, USA.
⁴ Department of Surgery, University of California, Irvine, 333 City Boulevard West, Suite 1600, Orange, CA 92868, USA.

Abstract

Laser speckle imaging (LSI) is a wide-field, noninvasive optical technique that allows researchers and clinicians to quantify blood flow in a variety of applications. However, traditional LSI devices are cart or tripod based mounted systems that are bulky and potentially difficult to maneuver in a clinical setting. We previously showed that the use of a handheld LSI device with the use of a fiducial marker (FM) to account for motion artifact is a viable alternative to mounted systems. Here we incorporated a handheld gimbal stabilizer (HGS) to produce a motion stabilized LSI (msLSI) device to further improve the quality of data acquired in handheld configurations. We evaluated the msLSI device in vitro using flow phantom experiments and in vivo using a dorsal window chamber model. For in vitro experiments, we quantified the speckle contrast of the FM (K_FM) using the mounted data set and tested 80% and 85% of K_FM as thresholds for useable images (K_{FM,Mounted,80%} and K_{FM,Mounted,85%}). Handheld data sets using the msLSI device (stabilized handheld) and handheld data sets without the HGS (handheld) were collected. Using K_{FM,Mounted,80%} and K_{FM,Mounted,85%} as the threshold, the number of images above the threshold for stabilized handheld (38 ± 7 and 10 ± 2) was significantly greater (p = 0.031) than for handheld operation (16 ± 2 and 4 ± 1). We quantified a region of interest within the flow region (K_FLOW), which led to a percent difference of 8.5% ± 2.9% and 7.8% ± 3.1% between stabilized handheld and handheld configurations at each threshold. For in vivo experiments, we quantified the speckle contrast of the window chamber (K_WC) using the mounted data set and tested 80% of K_WC (K_{WC,Mounted,80%}). Stabilized handheld operation provided 53 ± 24 images above K_{WC,Mounted,80%}, while handheld operation provided only 23 ± 13 images. We quantified the speckle flow index (SFI) of the vessels and the background to calculate a signal-to-background ratio (SBR) of the window chamber. Stabilized handheld operation provided a greater SBR (2.32 ± 0.29) compared to handheld operation (1.83 ± 0.21). Both the number of images above threshold and SBR were statistically significantly greater in the stabilized handheld data sets (p = 0.0312). These results display the improved usability of handheld data acquired with an msLSI device.

Abstract

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