Volume 11, Issue 8 e201700123
FULL ARTICLE

Assessment of the dynamics of human glymphatic system by near-infrared spectroscopy

Teemu Myllylä

Corresponding Author

Teemu Myllylä

Optoelectronics and Measurement Techniques Unit, University of Oulu, Oulu, Finland

Oulu Functional Neuroimaging Group, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland

Correspondence

Teemu Myllylä, Optoelectronics and Measurement Techniques Unit, University of Oulu, Oulu, Finland.Email: [email protected]

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Markus Harju

Markus Harju

Inverse Problems Group, Department of Mathematical Sciences, University of Oulu, Oulu, Finland

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Vesa Korhonen

Vesa Korhonen

Oulu Functional Neuroimaging Group, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland

Department of Diagnostic Radiology, Medical Research Center (MRC), Oulu University Hospital, Oulu, Finland

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Alexander Bykov

Alexander Bykov

Optoelectronics and Measurement Techniques Unit, University of Oulu, Oulu, Finland

Department of Photonics and Optical Information Technology, ITMO University, St Petersburg, Russia

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Vesa Kiviniemi

Vesa Kiviniemi

Oulu Functional Neuroimaging Group, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland

Department of Diagnostic Radiology, Medical Research Center (MRC), Oulu University Hospital, Oulu, Finland

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Igor Meglinski

Igor Meglinski

Optoelectronics and Measurement Techniques Unit, University of Oulu, Oulu, Finland

Department of Photonics and Optical Information Technology, ITMO University, St Petersburg, Russia

Institute of Biology, Irkutsk State University, Irkutsk, Russia

Institute of Engineering Physics for Biomedicine, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow, Russia

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First published: 12 August 2017
Citations: 37
Funding information Academy of Finland, Grant/Award numbers: 250215, 290596; Russian Science Foundation, Grant/Award number: 15-14-10008; Jane and Aatos Erkko Foundation; European Regional Development Fund

Abstract

Fluctuations in brain water content has attracted increasing interest, particularly as regards studies of the glymphatic system, which is connected with the complex organization of dural lymphatic vessels, responsible for cleaning tissue. Disturbances of glymphatic circulation are associated with several brain disorders, including dementia. This article introduces an approach to noninvasive measurement of water dynamics in the human brain utilizing near-infrared spectroscopy (NIRS). We demonstrate the possibility to sense dynamic variations of water content between the skull and grey matter, for instance, in the subarachnoid space. Measured fluctuations in water content, especially in the cerebrospinal fluid (CSF), are assumed to be correlated with the dynamics of glymphatic circulation. The sampling volume for the NIRS optode was estimated by Monte Carlo modelling for the wavelengths of 660, 740, 830 and 980 nm. In addition, using combinations of these wavelengths, this article presents the calculation models for quantifying water and haemodynamics. The presented NIRS technique allows long-term functional brain monitoring, including sleeping time. Furthermore, it is used in combination with different magnetic neuroimaging techniques, particularly magnetic resonance encephalography. Using the combined setup, we report the preliminary results on the interaction between CSF and blood oxygen level-dependent fluctuations.

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