A multipixel diffuse correlation spectroscopy system based on a single photon avalanche diode array

Johansson, Johannes; Portaluppi, Davide; Buttafava, Mauro; Villa, Federica

doi:10.1002/jbio.201900091

Cited by 27 publications

(18 citation statements)

References 37 publications

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“…To improve upon the single speckle limitations of conventional DCS measurements, multiple colocalized detectors are used to increase SNR 4 , 5 and as a proof of principle, at a short separation (11 mm), Sie et al. 6 have recently reported a

SNR gain of 32 (

) using a

SPAD camera to enable multi-speckle detection.…”

Section: Introductionmentioning

confidence: 99%

Superconducting nanowire single-photon sensing of cerebral blood flow

et al. 2021

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. Significance: The ability of diffuse correlation spectroscopy (DCS) to measure cerebral blood flow (CBF) in humans is hindered by the low signal-to-noise ratio (SNR) of the method. This limits the high acquisition rates needed to resolve dynamic flow changes and to optimally filter out large pulsatile oscillations and prevents the use of large source-detector separations ( ), which are needed to achieve adequate brain sensitivity in most adult subjects. Aim: To substantially improve SNR, we have built a DCS device that operates at 1064 nm and uses superconducting nanowire single-photon detectors (SNSPD). Approach: We compared the performances of the SNSPD-DCS in humans with respect to a typical DCS system operating at 850 nm and using silicon single-photon avalanche diode detectors. Results: At a 25-mm separation, we detected times more photons and achieved an SNR gain of on the forehead of 11 subjects using the SNSPD-DCS as compared to typical DCS. At this separation, the SNSPD-DCS is able to detect a clean pulsatile flow signal at 20 Hz in all subjects. With the SNSPD-DCS, we also performed measurements at 35 mm, showing a lower scalp sensitivity of with respect to the scalp sensitivity at 25 mm for both the 850 and 1064 nm systems. Furthermore, we demonstrated blood flow responses to breath holding and hyperventilation tasks. Conclusions: While current commercial SNSPDs are expensive, bulky, and loud, they may allow for more robust measures of non-invasive cerebral perfusion in an intensive care setting.

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SNR gain of 32 (

) using a

SPAD camera to enable multi-speckle detection.…”

Section: Introductionmentioning

confidence: 99%

Superconducting nanowire single-photon sensing of cerebral blood flow

et al. 2021

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“…Recently developed highly parallelized DCS (PaDS) demonstrates that detecting multiple speckles across many optical sensor pixels results in significantly faster correlation sampling rate Johansson et al (2019); Liu et al (2021a);Sie et al (2020); Xu et al (2021b); Zhou et al (2021). Further, advances in contrastive representation learning Liu et al (2021b) facilitates the use of deep artificial neural networks to create an embedding space where similar inputs of unique sub-types are clustered together without any data labeling required.…”

Section: Introductionmentioning

confidence: 99%

Transient motion classification through turbid volumes via parallelized single-photon detection and deep contrastive embedding

Xu¹,

Liu²,

Yang³

et al. 2022

Preprint

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Fast noninvasive probing of spatially varying decorrelating events, such as cerebral blood flow beneath the human skull, is an essential task in various scientific and clinical settings. One of the primary optical techniques used is diffuse correlation spectroscopy (DCS), whose classical implementation uses a single or few single-photon detectors, resulting in poor spatial localization accuracy and relatively low temporal resolution. Here, we propose a technique termed Classifying Rapid decorrelation Events via Parallelized single photon dEtection (CREPE), a new form of DCS that can probe and classify different decorrelating movements hidden underneath turbid volume with high sensitivity using parallelized speckle detection from a 32 × 32 pixel SPAD array. We evaluate our setup by classifying different spatiotemporal-decorrelating patterns hidden beneath a 5mm tissue-like phantom made with rapidly decorrelating dynamic scattering media. Twelve multi-mode fibers are used to collect scattered light from different positions on the surface of the tissue phantom. To validate our setup, we generate perturbed decorrelation patterns by both a digital micromirror device (DMD) modulated at multi-kilo-hertz rates, as well as a vessel phantom containing flowing fluid. Along with a deep contrastive learning algorithm that outperforms classic unsupervised learning methods, we demonstrate our approach can accurately detect and classify different transient decorrelation events (happening in 0.1-0.4s) underneath turbid scattering media, without any data labeling. This has the potential to be applied to noninvasively monitor deep tissue motion patterns, for example identifying normal or abnormal cerebral blood flow events, at multi-Hertz rates within a compact and static detection probe.

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“…mDCS is a new promising method to improve on the SNR of DCS through multiple independent measurements of the speckle field. The mDCS technique has been pursued in various ways using 28 stand-alone single-photon avalanche diodes (SPADs), 10 , 26 8 stand-alone SPADs, 27 4 pixels of a

SPAD array, 28 and interferometric near-infrared spectroscopy detecting 20 speckles with a CMOS camera. 29 While these prior approaches are important proofs of principle of mDCS, the largest improvement in SNR reported so far is an SNR gain (defined as the ratio between the SNR achieved with mDCS and with single-speckle DCS using detectors with the same performance) of 5.…”

Section: Introductionmentioning

confidence: 99%

High-sensitivity multispeckle diffuse correlation spectroscopy

et al. 2020

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Significance: Cerebral blood flow is an important biomarker of brain health and function as it regulates the delivery of oxygen and substrates to tissue and the removal of metabolic waste products. Moreover, blood flow changes in specific areas of the brain are correlated with neuronal activity in those areas. Diffuse correlation spectroscopy (DCS) is a promising noninvasive optical technique for monitoring cerebral blood flow and for measuring cortex functional activation tasks. However, the current state-of-the-art DCS adoption is hindered by a trade-off between sensitivity to the cortex and signal-to-noise ratio (SNR). Aim: We aim to develop a scalable method that increases the sensitivity of DCS instruments. Approach: We report on a multispeckle DCS (mDCS) approach that is based on a 1024-pixel single-photon avalanche diode (SPAD) camera. Our approach is scalable to >100;000 independent speckle measurements since large-pixel-count SPAD cameras are becoming available, owing to the investments in LiDAR technology for automotive and augmented reality applications. Results: We demonstrated a 32-fold increase in SNR with respect to traditional single-speckle DCS. Conclusion: A mDCS system that is based on a SPAD camera serves as a scalable method toward high-sensitivity DCS measurements, thus enabling both high sensitivity to the cortex and high SNR.

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A multipixel diffuse correlation spectroscopy system based on a single photon avalanche diode array

Cited by 27 publications

References 37 publications

Superconducting nanowire single-photon sensing of cerebral blood flow

Superconducting nanowire single-photon sensing of cerebral blood flow

Transient motion classification through turbid volumes via parallelized single-photon detection and deep contrastive embedding

High-sensitivity multispeckle diffuse correlation spectroscopy

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