Assessment of the dynamics of human glymphatic system by near‐infrared spectroscopy. Issue 8 (19th December 2017)

• Record Type: Journal Article
• Authors: Myllylä, Teemu; Harju, Markus; Korhonen, Vesa; Bykov, Alexander; Kiviniemi, Vesa; Meglinski, Igor
• Other Names: Galanzha Ekaterina guestEditor.; Zharov Vladimir P. guestEditor.; Tuchin Valery V. guestEditor.
• Is Part Of: Journal of biophotonics. Volume 11:Issue 8(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-12-19
• Subjects: brain -- CSF -- glymphatic system -- lymph -- MRI -- Near‐infrared spectroscopy -- NIRS; Photonics -- Periodicals; Optical materials -- Periodicals; Optics -- Periodicals; Medical instruments and apparatus -- Periodicals; 621.3605
• DOI: 10.1002/jbio.201700123
• Languages: English
• ISSNs: 1864-063X

Abstract

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. Abstract : Monte Carlo‐simulated scattering map for photons at a wavelength of 980 nm propagating inside the human head model. Most scattering takes place in the skull layer. However, a significant amount of photons travels further through the areas where cerebrospinal fluid (CSF) flows. Our experiments demonstrate that using 980 nm in combination with 830 and 660 nm or 740 nm allows the simultaneous sensing of dynamic variations in water volume and haemodynamics in the human brain cortex. Observed fluctuations are assumed to be correlated with the dynamics of glymphatic circulation.