Real-time video-rate perfusion imaging using multi-exposure laser speckle contrast imaging and machine learning

Hultman, Martin; Larsson, Marcus; Strömberg, Tomas; Fredriksson, Ingemar

doi:10.1117/1.jbo.25.11.116007

Cited by 13 publications

(20 citation statements)

References 31 publications

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“…The MELSCI instrument used in this study has been thoroughly described in previous publications 18 , 33 . In summary, the technique is based on the continuous acquisition of images with 1 ms exposure time from a 1000 frames-per-second high-speed CMOS sensor.…”

Section: Methodsmentioning

confidence: 99%

“…Further, the accumulation and speckle contrast algorithms are implemented in a field-programmable gate array (FPGA) closely integrated with the CMOS sensor. This enables continuous real-time acquisition and processing of multi-exposure contrast images, without any loss of information due to the negligible interframe time 18 . Each set of 64 speckle images results in one multi-exposure contrast image, enabling a framerate for perfusion images of 15.6 frames-per-second.…”

Section: Methodsmentioning

confidence: 99%

“…Similar techniques have been used to estimate blood oxygen saturation from spectral data 16 , 17 . This offloads the heavy computations to the training stage of the network and enables real-time estimations of microcirculation properties in imaging modalities 18 …”

Section: Introductionmentioning

confidence: 99%

“… 16 , 17 This offloads the heavy computations to the training stage of the network and enables real-time estimations of microcirculation properties in imaging modalities. 18 …”

Section: Introductionmentioning

confidence: 99%

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Speed-resolved perfusion imaging using multi-exposure laser speckle contrast imaging and machine learning

et al. 2023

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Significance: Laser speckle contrast imaging (LSCI) gives a relative measure of microcirculatory perfusion. However, due to the limited information in single-exposure LSCI, models are inaccurate for skin tissue due to complex effects from e.g. static and dynamic scatterers, multiple Doppler shifts, and the speed-distribution of blood. It has been demonstrated how to account for these effects in laser Doppler flowmetry (LDF) using inverse Monte Carlo (MC) algorithms. This allows for a speed-resolved perfusion measure in absolute units %RBC × mm/s, improving the physiological interpretation of the data. Until now, this has been limited to a single-point LDF technique but recent advances in multi-exposure LSCI (MELSCI) enable the analysis in an imaging modality.Aim: To present a method for speed-resolved perfusion imaging in absolute units %RBC × mm/s, computed from multi-exposure speckle contrast images.Approach: An artificial neural network (ANN) was trained on a large simulated dataset of multi-exposure contrast values and corresponding speed-resolved perfusion. The dataset was generated using MC simulations of photon transport in randomized skin models covering a wide range of physiologically relevant geometrical and optical tissue properties. The ANN was evaluated on in vivo data sets captured during an occlusion provocation.Results: Speed-resolved perfusion was estimated in the three speed intervals 0 to 1 mm∕s, 1 to 10 mm∕s, and >10 mm∕s, with relative errors 9.8%, 12%, and 19%, respectively. The perfusion had a linear response to changes in both blood tissue fraction and blood flow speed and was less affected by tissue properties compared with single-exposure LSCI. The image quality was subjectively higher compared with LSCI, revealing previously unseen macro-and microvascular structures. Conclusions:The ANN, trained on modeled data, calculates speed-resolved perfusion in absolute units from multi-exposure speckle contrast. This method facilitates the physiological interpretation of measurements using MELSCI and may increase the clinical impact of the technique.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“… 16 , 17 This offloads the heavy computations to the training stage of the network and enables real-time estimations of microcirculation properties in imaging modalities. 18 …”

Section: Introductionmentioning

confidence: 99%

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Speed-resolved perfusion imaging using multi-exposure laser speckle contrast imaging and machine learning

et al. 2023

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“…Optical, non-invasive diagnostics offer a good range of methods for the evaluation of the functional insufficiency in the components of tissue vitality including blood microcirculation system. The methods are based on such approaches as fluorescence spectroscopy [ 6 ], diffuse reflectance spectrocopy [ 7 , 8 , 9 ], speckle contrast imaging [ 10 ], photopletismography [ 11 ], videocapillaroscopy [ 12 ] and methods based on coherent light scattering and optical coherence tomography [ 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Laser Doppler Spectrum Analysis Based on Calculation of Cumulative Sums Detects Changes in Skin Capillary Blood Flow in Type 2 Diabetes Mellitus

et al. 2021

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In this article, we introduce a new method of signal processing and data analysis for the digital laser Doppler flowmetry. Our approach is based on the calculation of cumulative sums over the registered Doppler power spectra. The introduced new parameter represents an integral estimation for the redistribution of moving red blood cells over the range of speed. The prototype of the device implementing the technique is developed and tested in preliminary clinical trials. The methodology was verified with the involvement of two age groups of healthy volunteers and in a group of patients with type 2 diabetes mellitus. The main practical result of the study is the development of a set of binary linear classifiers that allow the method to identify typical patterns of the microcirculation for the healthy volunteers and diabetic patients based on the presented diagnostic algorithm.

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Comprehensive imaging of microcirculatory changes in the foot during endovascular intervention – A technical feasibility study

Hultman

Aronsson

Fredriksson

et al. 2022

Microvascular Research

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Real-time video-rate perfusion imaging using multi-exposure laser speckle contrast imaging and machine learning

Cited by 13 publications

References 31 publications

Speed-resolved perfusion imaging using multi-exposure laser speckle contrast imaging and machine learning

Speed-resolved perfusion imaging using multi-exposure laser speckle contrast imaging and machine learning

Laser Doppler Spectrum Analysis Based on Calculation of Cumulative Sums Detects Changes in Skin Capillary Blood Flow in Type 2 Diabetes Mellitus

Comprehensive imaging of microcirculatory changes in the foot during endovascular intervention – A technical feasibility study

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