Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

Abstract

Improved Laser Speckle Contrast Imaging (LSCI) blood flow analyses that incorporate inverse models of the underlying laser-tissue interaction have been used to develop more quantitative implementations of speckle flowmetry such as Multi-Exposure Speckle Imaging (MESI). In this paper, we determine the optimal camera exposure durations required for obtaining flow information with comparable accuracy with the prevailing MESI implementation utilized in recent in vivo rodent studies. A looping leave-one-out (LOO) algorithm was used to identify exposure subsets which were analyzed for accuracy against flows obtained from analysis with the original full exposure set over 9 animals comprising n = 314 regional flow measurements. From the 15 original exposures, 6 exposures were found using the LOO process to provide comparable accuracy, defined as being no more than 10% deviant, with the original flow measurements. The optimal subset of exposures provides a basis set of camera durations for speckle flowmetry studies of the microcirculation and confers a twofold faster acquisition rate and a 28% reduction in processing time without sacrificing accuracy. Additionally, the optimization process can be used to identify further reductions in the exposure subsets for tailoring imaging over less expansive flow distributions to enable even faster imaging.

Acute simvastatin treatment restores cerebral functional capillary density and attenuates angiotensin II‐induced microcirculatory changes in a model of primary hypertension

“…[69][70][71] More elaborated implementations and calibrations (i.e., multiexposure imaging) may enhance the accurate extraction of blood flow dynamics from imaged speckles. 72 In the present study, hypertensive rats presented a reduction in relative basal mCBF compared to normotensive WKY rats, and SIM treatment normalized relative mCBF in hypertensive rats. Similarly, it has been demonstrated that atorvastatin increases mCBF in stroke-prone SHRs.…”

Laser Speckle Contrast Imaging for Monitoring Changes in Microvascular Blood Flow

“…The region of interest (ROI) was set to cover a physical area of 1 cm 2 , and the settings were either high spatial resolution/low recording speed (sampling rate) (HRLS; 1 frame/s) or low spatial resolution/high recoding speed (LRHS; 25 frames/s). These settings are commonly used in research and clinical settings to investigate changes in blood flow [16]. …”

The effect of calf neuromuscular electrical stimulation and intermittent pneumatic compression on thigh microcirculation

“…A display rate of 25 Hz, and a time constant of 0.3 s was used to account for rapid blood flow changes and achieve optimum contrast through reducing the image noise. The camera was placed 25-30 cm from the skin as advised by the manufacturer's instructional manual, with the camera resolution set at 152×113 pixels/cm 2 for spatial processing and directed perpendicular to the thigh (Bezemer et al, 2010;Kazmi et al, 2014). Resulting images were digitized and analysed off-line using the moorFLPI software (Full Field Laser Perfusion Imager Review v4.0, Moor Instruments, Devon, United Kingdom).…”