Microstates analysis for dry and gel-based multichannel electroencephalography. - In: 9th European Medical and Biological Engineering Conference, (2024), S. 122-130
Spatial analysis of EEG data, e.g. using short-term stable microstates, is increasingly used in neuroscience and clinical applications. At the same time, scenarios involving mobility, sports, and home-based activities are becoming more prevalent in EEG studies. For this purpose, dry EEG electrodes are more and more commonly used. Thus, our objective was a comparison of microstates analysis between dry and gel-based EEGs. 256-channel EEGs were recorded from 30 volunteers using dry and gel-based electrodes during resting state eyes closed and eyes open. Microstates were extracted for each measurement and time-domain parameters were calculated. We found a high degree of consistency between the microstate maps extracted from dry and gel-based measurements for both eyes closed and eyes open conditions. The topographic similarities between the average maps for dry and gel-based recordings were above 81.5% for each of the seven extracted maps. We conclude that topographic microstate analyses are feasible using multichannel EEG setups with new dry EEG electrodes.
Characterization of a new fluorescence lifetime imaging ophthalmoscope. - In: Acta ophthalmologica, ISSN 1755-3768, Bd. 102 (2024), S279, insges. 1 S.
Aims/Purpose: Fluorescence lifetime imaging ophthalmoscopy (FLIO) allows in vivo measurement of autofluorescence intensity decays of endogenous fluorophores in the ocular fundus. So far, only devices from Heidelberg Engineering based on the Spectralis system have been used in FLIO research. Here, we present and characterize a new FLIO device based on the RETImap system from Roland Consult. Methods: The device is based on a confocal scanning laser ophthalmoscope (35˚ field, 512 × 512 px). A ps diode laser (BDL-SMN 473 nm, Becker & Hickl GmbH, Berlin, Germany) excites autofluorescence. The fluorescence photons are split into a short (498-560 nm, SSC) and a long (560-720 nm, LSC) spectral channel (one HPM-100-40 detector [Becker & Hickl GmbH] each) and are detected by time-correlated single photon counting (SPC-160, Becker & Hickl GmbH). We determined the maximum laser power (ILT2400, International Light Technologies, Inc. Peabody, MA, USA) and analysed the instrument's behaviour at three different laser power levels (150 μW, 200 μW and max.) in terms of laser spectrum (CAS140CT, Instrument Systems GmbH, Munich, Germany) and instrument response function (IRF). The IRF was determined using a 25 μM Eosin Y solution, mixed with a 5 M solution of potassium iodide, placed in a flat cuvette (110-OS, Hellma GmbH & Co. KG, Müllheim, Germany) in front of the objective lens of the FLIO device. Fluorescence measurements of approximately 1-min duration were performed three times for all three laser powers. The IRF and the full width at half maximum (FWHM) were calculated using FLIMX software (www.flimx.de). Results: The max. laser power was 280 μW. The peak wavelengths of the laser spectra were 467.6 (150 μW), 467.9 (200 μW) and 468.0 nm (280 μW). IRF FWHM in SSC were 298.6 ± 1.1 ps (150 μW), 341.0 ± 2.5 ps (200 μW) and 347.5 ± 6.0 ps (280 μW). In LSC, the IRF FWHM were 290.4 ± 3.8 ps (150 μW), 344.0 ± 3.4 ps (200 μW) and 358.8 ± 1.3 ps (280 μW). Results are mean ± standard deviation. Conclusions: A new fluorescence lifetime imaging ophthalmoscope has been characterized. The device offers a high laser power for fluorescence excitation, a large field of view, a high spatial resolution, and a sufficiently high time resolution. Thus, it is suitable for fluorescence lifetime studies.
https://doi.org/10.1111/aos.15921
Comfortable dry EEG using Flower electrodes. - In: Biomedical engineering, ISSN 1862-278X, Bd. 68 (2023), S. 221
https://doi.org/10.1515/bmte-2023-2001
Pilot study on the effect of a transocular alternating current stimulation on the steady-state pattern-reversal electroretinogram. - In: Biomedical engineering, ISSN 1862-278X, Bd. 68 (2023), S. 212
https://doi.org/10.1515/bmte-2023-2001
Amplitude fluctuations in the averaged photic driving in the electroencephalogram correspond to burst occurrence in single trials. - In: Biomedical engineering, ISSN 1862-278X, Bd. 68 (2023), S. 209
https://doi.org/10.1515/bmte-2023-2001
Detailed anatomical neck model for electromagnetic simulations. - In: Biomedical engineering, ISSN 1862-278X, Bd. 68 (2023), S. 181
https://doi.org/10.1515/bmte-2023-2001
Exploring the orientation dependency of nondipolar frequency shifts in magnetic resonance imaging: an approach to unveil chemical exchange and tissue microstructure in the brain. - In: Biomedical engineering, ISSN 1862-278X, Bd. 68 (2023), S. 166
https://doi.org/10.1515/bmte-2023-2001
Deep learning enables a novel magnetic resonance imaging contrast that unveils chemical and microstructural brain tissue changes through nondipolar larmor frequency shifts. - In: Biomedical engineering, ISSN 1862-278X, Bd. 68 (2023), S. 160
https://doi.org/10.1515/bmte-2023-2001
Mapping the anisotropy of tissue magnetic susceptibility from single-orientation magnetic resonance imaging. - In: Biomedical engineering, ISSN 1862-278X, Bd. 68 (2023), S. 156
https://doi.org/10.1515/bmte-2023-2001
Real-time smartphone-assisted EEG electrode localization and augmented reality application. - In: Biomedical engineering, ISSN 1862-278X, Bd. 68 (2023), S. 153
https://doi.org/10.1515/bmte-2023-2001