High-speed multi-exposure laser speckle contrast imaging with a single-photon counting camera

Dragojević, Tanja; Bronzi, Danilo; Varma, Hari M.; Valdés, Claudia P.; Castellví, Clara; Villa, Federica; Tosi, Alberto; Justicia, Carles; Zappa, Franco; Durdurán, Turgut

doi:10.1364/boe.6.002865

Cited by 52 publications

(47 citation statements)

References 20 publications

(32 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These motions are classified as ordered motion (ordered flow of the scatterers) and disordered motion (Brownian motion) which occurs due to the effect of temperature [16]. The dynamic scatterers motion was historically considered to be close to Brownian motion [1], [16], [19], [29], [31]- [33] and with single scattering contribution [34]. This approach was used with the argument that the blood circulation is dense and turbulent [31].…”

Section: Motion Distributionsmentioning

confidence: 99%

“…However, the model that should be used for the autocorrelation function is still a major investigation field in LSCI [1]. Currently, the Lorentzian model is the most used in laser speckle studies [29], [33], [36]- [38] because the ordered flow is approximated by a Lorentzian distribution when scattering is random and uncorrelated [39]. Nevertheless, several authors [16], [40], [41] claim that the Gaussian distribution should be used.…”

Section: Motion Distributionsmentioning

confidence: 99%

“…In other words, it increases the speckle contrast [28]. The static scatterers issue has been neglected in the past [23], [43], [48] but nowadays it is often accounted for [29], [34]. The existence of static scatterers has been addressed by Parthasarathy et al [25] and Zakharov et al [49] who presented a new method to compute accurate values of τ c .…”

Section: E Effect Of Static Scatterersmentioning

confidence: 99%

See 2 more Smart Citations

Laser Speckle Imaging to Monitor Microvascular Blood Flow: A Review

Vaz

Humeau-Heurtier

Figueiras

et al. 2016

IEEE Rev. Biomed. Eng.

101

View full text Add to dashboard Cite

Laser speckle is a complex interference phenomenon that can easily be understood, in concept, but is difficult to predict mathematically, because it is a stochastic process. The use of laser speckle to produce images, which can carry many types of information, is called laser speckle imaging (LSI). The biomedical applications of LSI started in 1981 and, since then, many scientists have improved the laser speckle theory and developed different imaging techniques. During this process, some inconsistencies have been propagated up to now. These inconsistencies should be clarified in order to avoid errors in future works. This review presents a review of the laser speckle theory used in biomedical applications. Moreover, we also make a review of the practical concepts that are useful in the construction of laser speckle imagers. This study is not only an exposition of the concepts that can be found in the literature but also a critical analysis of the investigations presented so far. Concepts like scatterers velocity distribution, effect of static scatterers, optimal speckle size, light penetration angle, and contrast computation algorithms are discussed in detail.

show abstract

Section: Motion Distributionsmentioning

confidence: 99%

Section: Motion Distributionsmentioning

confidence: 99%

Section: E Effect Of Static Scatterersmentioning

confidence: 99%

See 1 more Smart Citation

Laser Speckle Imaging to Monitor Microvascular Blood Flow: A Review

Vaz

Humeau-Heurtier

Figueiras

et al. 2016

IEEE Rev. Biomed. Eng.

101

View full text Add to dashboard Cite

show abstract

“…This enables observation of fluctuations of the optical signal from larger areas of tissue. 15 In recent clinical studies, both optical techniques, trNIRS and DCS, have been combined to monitor CBF and oxygenation of brain tissue simultaneously. This multimodal approach allows regional evaluation of the cerebral metabolism ratio of oxygen (CMRO 2 ), which is a physiological parameter useful in the diagnosis of brain disorders.…”

Section: Physical and Technical Backgroundmentioning

confidence: 99%

Application of optical methods in the monitoring of traumatic brain injury: A review

Weigl

Milej

Janusek

et al. 2016

J Cereb Blood Flow Metab

View full text Add to dashboard Cite

We present an overview of the wide range of potential applications of optical methods for monitoring traumatic brain injury. The MEDLINE database was electronically searched with the following search terms: “traumatic brain injury,” “head injury,” or “head trauma,” and “optical methods,” “NIRS,” “near-infrared spectroscopy,” “cerebral oxygenation,” or “cerebral oximetry.” Original reports concerning human subjects published from January 1980 to June 2015 in English were analyzed. Fifty-four studies met our inclusion criteria. Optical methods have been tested for detection of intracranial lesions, monitoring brain oxygenation, assessment of brain perfusion, and evaluation of cerebral autoregulation or intracellular metabolic processes in the brain. Some studies have also examined the applicability of optical methods during the recovery phase of traumatic brain injury . The limitations of currently available optical methods and promising directions of future development are described in this review. Considering the outstanding technical challenges, the limited number of patients studied, and the mixed results and opinions gathered from other reviews on this subject, we believe that optical methods must remain primarily research tools for the present. More studies are needed to gain confidence in the use of these techniques for neuromonitoring of traumatic brain injury patients.

show abstract

“…To overcome the slow acquisition process using a standard MELSCI setup Dragojević et al used a high speed single‐photon avalanche diode (SPAD) in order to capture low‐resolution images with very short exposure time and inter‐frame delay. These images were then accumulated numerically in the post processing to create longer synthetic exposure times.…”

Section: Introductionmentioning

confidence: 99%

A 15.6 frames per second 1‐megapixel multiple exposure laser speckle contrast imaging setup

Hultman

Fredriksson

Larsson

et al. 2017

Journal of Biophotonics

View full text Add to dashboard Cite

A multiple exposure laser speckle contrast imaging (MELSCI) setup for visualizing blood perfusion was developed using a field programmable gate array (FPGA), connected to a 1000 frames per second (fps) 1-megapixel camera sensor. Multiple exposure time images at 1, 2, 4, 8, 16, 32 and 64 milliseconds were calculated by cumulative summation of 64 consecutive snapshot images. The local contrast was calculated for all exposure times using regions of 4 × 4 pixels. Averaging of multiple contrast images from the 64-millisecond acquisition was done to improve the signal-tonoise ratio. The results show that with an effective implementation of the algorithm on an FPGA, contrast images at all exposure times can be calculated in only 28 milliseconds. The algorithm was applied to data recorded during a 5 minutes finger occlusion. Expected contrast changes were found during occlusion and the following hyperemia in the occluded finger, while unprovoked fingers showed constant contrast during the experiment. The developed setup is capable of massive data processing on an FPGA that enables processing of MELSCI data in 15.6 fps (1000/64 milliseconds). It also leads to improved frame rates, enhanced image quality and enables the calculation of improved microcirculatory perfusion estimates compared to single exposure time systems.

show abstract

High-speed multi-exposure laser speckle contrast imaging with a single-photon counting camera

Cited by 52 publications

References 20 publications

Laser Speckle Imaging to Monitor Microvascular Blood Flow: A Review

Laser Speckle Imaging to Monitor Microvascular Blood Flow: A Review

Application of optical methods in the monitoring of traumatic brain injury: A review

A 15.6 frames per second 1‐megapixel multiple exposure laser speckle contrast imaging setup

Contact Info

Product

Resources

About