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Category Archives: sfNIRS2024-Session-2
Sa-079-Regional differences in microvascular regulatory control during ephemeral blood pressure perturbations
Regional cortical differences in dynamic cerebral autoregulation were assessed using functional near-infrared spectroscopy-derived transfer function analysis (TFA) estimates. Thirty-two participants (23 females) completed repeated squat-stand maneuvers at 0.05 and 0.10 Hz with TFA outcome metrics of phase and normalized gain across motor, frontal, dorsolateral prefrontal, somatosensory, and occipital cortices. Multiple linear regressions noted no differences with biological sex or hemisphere; however, a greater normalized gain and greater phase was present in the occipital cortex. These insights enhance the understanding of cerebral blood flow regulation and emphasize the complexity of vascular responses across different brain regions. Continue reading
Sa-033-Investigating brain specialization for song and speech at birth
The neural mechanisms underlying the perception of songs at birth are as yet little explored. However, the processing of songs might be particularly relevant to investigate as it requires the ability to process musical and linguistic information simultaneously. The current work explores this compelling question by measuring newborns’ responses to speech, song and hummed sentences, with fNIRS. Continue reading
Sa-035-Investigating the haemodynamic response to hypo-glycaemia in preterm infants using diffuse optical tomography
Very preterm neonates are prone to experience hyper and hypo-glycaemia. This study uses continuous glucose monitoring and diffuse optical tomography (DOT) to investigate the haemodynamic response to these events. 60 preterms were recruited, with the glycaemic events currently classified in 41 patients. Among these, preterms that exhibited hypo-glycaemia only (14/41) were selected for this preliminary analysis. A technique for correcting motion artefact ‘trains’ was developed to pre-process the data and currently analysis of DOT has been performed on 5/14 preterms, on several events. Analysis of all 14 hypo only preterms are planned with group wide comparisons. Continue reading
Sa-039-Contrast-enhanced diffuse optical tomography in acute, moderate and severe traumatic brain injury: a prospective observational study
Contrast-enhanced diffuse optical tomography (DOT) could monitor the heterogenous cerebral perfusion in traumatic brain injury (TBI) (1, 2). We present the first contrast-enhanced DOT study in acute, moderate and severe TBI in the intensive care unit. Changes of absorption coefficient in the intracranial (ICT) and extracranial tissues (ECT) following two injections of indocyanine green (ICG) were scanned using DOT on 10 TBI patients. The ICG kinetic and brain lesions were compared. The width parameter (seconds) and lesion locations agreed in the ICT (p=3.5·10-3), but not in the ECT (p=1.8·10-1). Pathological cerebral perfusion were retrieved using DOT. Continue reading
Sa-042-A diffuse optical tomography system to scan acute traumatic brain injury patients in the intensive care unit: a prospective study on healthy volunteers
Diffuse optical tomography (DOT) is untested on traumatic brain injury (TBI) in the intensive care unit (ICU). We developed a system for this data acquisition and analysis. Probe displacements and monitoring of the intracranial (ICT) and extracranial tissues (ECT) were tested in 23 healthy volunteers during 5 Valsalva maneuvers, using DOT. Probe displacement of 5.5 mm, and a sufficient capacity to isolate oxyhemoglobin (O2Hb) (p=6.4·10-6) and total hemoglobin (HbT) (p=2.8·10-5) in the ICT from the ECT, and to monitor O2Hb (p=9.2·10-4) and HbT (p=1.0·10-3) in the ICT. The developed approach is suitable for TBI in the ICU. Continue reading
Sa-045-A digital instrument simulator to optimize the development of hyperspectral systems for intraoperative brain mapping
In this study, we developed a digital instrument simulator based on Monte Carlo simulations to obtain realistic images of exposed brain cortex. In addition, we developed an optimization procedure for identifying the optimal wavelength for resolving Haemoglobins and Cytochorme-C-Oxidase concentrations accross the visible and NIR range. Continue reading
Sa-013-Developing a novel brain-based biomarker of mild cognitive impairment using time-domain functional near-infrared spectroscopy
Global population aging has led to increasing concerns about mild cognitive impairment (MCI). In this study, we compare MCI patients to age-matched controls using Time-Domain functional Near-Infrared Spectroscopy (TD-fNIRS) brain recordings at rest and during a cognitive task. We found multiple metrics that differentiated the two groups, including absolute oxygenation, fractional Amplitude of Low Frequency Fluctuations (fALFF), and behavioral metrics. Future work will include building a classification model for MCI based on brain metrics. Continue reading
Sa-014-Developing a novel brain-based biomarker of depression treatment response using time-domain functional near-infrared spectroscopy
Despite the heavy burden of major depressive disorder, quantitative tools to guide clinicians in making treatment decisions are lacking. In this study, we measured depression patients longitudinally using Time-Domain functional Near-Infrared Spectroscopy (TD-fNIRS) brain recordings at rest and during a cognitive task. Patients were measured before they started treatment, after the first treatment, and at the end of treatment, and additional clinical and self-report data was collected. We found metrics that differentiated treatment responders from remitters, including neural responses during a verbal fluency task. Future work will include building a classification model for predicting depression treatment response. Continue reading
Sa-016-Studying conditions with brain inflammation using near-infrared spectroscopic techniques
Abstract: Measuring hypoxia and brain function is important to understand the impact of several pathologies involving brain inflammation and to investigate treatment effects. We use the frequency domain NIRS and functional NIRS in Multiple Sclerosis (MS) and post-acute COVID-19 syndrome (PACS). We show that cortical microvascular hypoxia occurs in MS and PACS and that functional connectivity may indicate brain function and adaptations. NIRS can provide useful biomarkers in several pathologies that are associated with inflammation, hypoxia, and reduced function. Continue reading
Sa-091-A Whole-head Fast Time-Domain Diffuse Optical Tomography System
We present the characterization and validation of the next-generation time-domain diffuse optical tomography (TD-DOT) system, Kernel Flow2. The Kernel Flow2 system has several updates from the first generation Kernel Flow system including a custom Application-Specific Integrated Circuit (ASIC), improved laser drivers, modules with integrated Instrument Response Function measurement, compact Fresnel optics, a redesigned headset layout for improved channel count and coverage, and increased headset comfort. We describe the system in detail and show reconstructed brain activations from a validation task in humans. Continue reading