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Hultman, Martin
Publications (2 of 2) Show all publications
Hultman, M., Fredriksson, I., Larsson, M., Alvandpour, A. & Strömberg, T. (2018). A 15.6 frames per second 1 megapixel Multiple Exposure Laser Speckle Contrast Imaging setup. Journal of Biophotonics, 11(2), Article ID e201700069.
Open this publication in new window or tab >>A 15.6 frames per second 1 megapixel Multiple Exposure Laser Speckle Contrast Imaging setup
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2018 (English)In: Journal of Biophotonics, ISSN 1864-063X, E-ISSN 1864-0648, Vol. 11, no 2, article id e201700069Article in journal (Refereed) Published
Abstract [en]

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-to-noise 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.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
blood flow, blood perfusion, FPGA, LASCA, LSCI, microcirculation, multiexposure
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:liu:diva-141201 (URN)10.1002/jbio.201700069 (DOI)000424643600014 ()2-s2.0-85026753968 (Scopus ID)
Funder
Swedish Research Council, 2014-6141
Available from: 2017-09-26 Created: 2017-09-26 Last updated: 2019-09-05Bibliographically approved
Hultman, M., Fredriksson, I., Strömberg, T. & Larsson, M. (2018). Evaluation of a high framerate multi-exposure laser speckle contrast imaging setup. In: Kevin K. Tsia, Keisuke Goda (Ed.), High-Speed Biomedical Imaging and Spectroscopy III: Toward Big Data Instrumentation and Management. Paper presented at SPIE BIOS 27 January - 1 February 2018 San Francisco, California, United States. SPIE - International Society for Optical Engineering
Open this publication in new window or tab >>Evaluation of a high framerate multi-exposure laser speckle contrast imaging setup
2018 (English)In: High-Speed Biomedical Imaging and Spectroscopy III: Toward Big Data Instrumentation and Management / [ed] Kevin K. Tsia, Keisuke Goda, SPIE - International Society for Optical Engineering, 2018Conference paper, Published paper (Refereed)
Abstract [en]

We present a first evaluation of a new multi-exposure laser speckle contrast imaging (MELSCI) system for assessing spatial variations in the microcirculatory perfusion. The MELSCI system is based on a 1000 frames per second 1-megapixel camera connected to a field programmable gate arrays (FPGA) capable of producing MELSCI data in realtime. The imaging system is evaluated against a single point laser Doppler flowmetry (LDF) system during occlusionrelease provocations of the arm in five subjects. Perfusion is calculated from MELSCI data using current state-of-the-art inverse models. The analysis displayed a good agreement between measured and modeled data, with an average error below 6%. This strongly indicates that the applied model is capable of accurately describing the MELSCI data and that the acquired data is of high quality. Comparing readings from the occlusion-release provocation showed that the MELSCI perfusion was significantly correlated (R=0.83) to the single point LDF perfusion, clearly outperforming perfusion estimations based on a single exposure time. We conclude that the MELSCI system provides blood flow images of enhanced quality, taking us one step closer to a system that accurately can monitor dynamic changes in skin perfusion over a large area in real-time

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
Series
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, ISSN 0277-786X ; 10505
National Category
Medical Engineering
Identifiers
urn:nbn:se:liu:diva-148844 (URN)10.1117/12.2286248 (DOI)000446339000015 ()978-1-5106-1496-3 (ISBN)
Conference
SPIE BIOS 27 January - 1 February 2018 San Francisco, California, United States
Available from: 2018-06-20 Created: 2018-06-20 Last updated: 2018-10-17
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