A5076554019- Optical Imaging and Spectroscopy Techniques
- Non-Invasive Vital Sign Monitoring
- Advanced MRI Techniques and Applications
- Photoacoustic and Ultrasonic Imaging
- Traumatic Brain Injury and Neurovascular Disturbances
- Neonatal and fetal brain pathology
- Spectroscopy Techniques in Biomedical and Chemical Research
- Hemodynamic Monitoring and Therapy
- Medical Imaging Techniques and Applications
- Advanced Neuroimaging Techniques and Applications
- MRI in cancer diagnosis
- Functional Brain Connectivity Studies
- Atomic and Subatomic Physics Research
- Cerebrovascular and Carotid Artery Diseases
- Lanthanide and Transition Metal Complexes
- Cardiovascular Health and Disease Prevention
- EEG and Brain-Computer Interfaces
- Cardiac Imaging and Diagnostics
- Musculoskeletal pain and rehabilitation
- Heart Rate Variability and Autonomic Control
- Neonatal Respiratory Health Research
- Traumatic Brain Injury Research
- Thermal Regulation in Medicine
- Rheumatoid Arthritis Research and Therapies
- Radiomics and Machine Learning in Medical Imaging
Western University
2016-2025
Lawson Health Research Institute
2016-2025
St Joseph's Health Care
2009-2024
Health Canada
2024
London Health Sciences Centre
2022
Drexel University
2022
Ontario Shores Centre for Mental Health Sciences
2022
University of Toronto
2022
Western University of Health Sciences
2022
Boston University
2022
Using the adiabatic approximation, which assumes that tracer concentration in parenchymal tissue changes slowly relative to capillaries, we derived a time-domain, closed-form solution of homogeneity model. This solution, is called similar form those two-compartment models, Owing its simplicity, can be used CBF experiments kinetic data with only limited time resolution or signal-to-noise ratio, both, are obtained. computer simulations, investigated accuracy and precision parameters for values...
To accurately quantify the radioactivity concentration measured by PET, emission data need to be corrected for photon attenuation; however, MRI signal cannot easily converted into attenuation values, making correction (AC) in PET/MRI challenging. In order further improve current vendor-implemented MR-AC methods absolute quantification, a number of prototype have been proposed literature. These can categorized three types: template/atlas-based, segmentation-based, and reconstruction-based....
This report is the second part of a comprehensive two-part series aimed at reviewing an extensive and diverse toolkit novel methods to explore brain health function. While first focused on neurophotonic tools mostly applicable animal studies, here, we highlight optical spectroscopy imaging relevant noninvasive human studies. We outline current state-of-the-art technologies software advances, most recent impact these neuroscience clinical applications, identify areas where innovation needed,...
Abstract Changes in the exchange rate of water across blood‐brain barrier, denoted k w , may indicate barrier dysfunction before leakage large‐molecule contrast agents is observable. A previously proposed approach for measuring to use diffusion‐weighted arterial spin labeling measure vascular and tissue fractions labeled water, because vascular‐to‐tissue ratio related . However, accuracy affected by blood contributions transit time (τ a ). To address these issues, two‐stage method that uses...
Significance: Near-infrared spectroscopy (NIRS) combined with diffuse correlation (DCS) provides a noninvasive approach for monitoring cerebral blood flow (CBF), oxygenation, and oxygen metabolism. However, these methods are vulnerable to signal contamination from the scalp. Our work evaluated of reducing impact this using time-resolved (TR) NIRS multidistance (MD) DCS. Aim: The magnitude scalp was by measuring flow, metabolic responses global hemodynamic challenge. Contamination assessed...
Resting-state functional connectivity (rsFC) has gained popularity mainly due to its simplicity and potential for providing insights into various brain disorders. In this vein, near-infrared spectroscopy (fNIRS) is an attractive choice portability, flexibility, low cost, allowing bedside imaging of function. While promising, fNIRS suffers from non-neural signal contaminations (i.e., systemic physiological noise), which can increase correlation across channels, leading spurious rsFC networks....
Purpose To present a pulse sequence and mathematical models for quantification of blood–brain barrier water exchange permeability. Methods Motion‐compensated diffusion‐weighted (MCDW) gradient‐and‐spin echo (GRASE) pseudo‐continuous arterial spin labeling (pCASL) was proposed to acquire intravascular/extravascular perfusion signals from five postlabeling delays (PLDs, 1590–2790 ms). Experiments were performed on 11 healthy subjects at 3 T. A comprehensive set permeability parameters...
Abstract Hypoxic-ischemic encephalopathy (HIE) results from a lack of oxygen to the brain during perinatal period. HIE can lead mortality and various acute long-term morbidities. Improved bedside monitoring methods are needed identify biomarkers health. Functional near-infrared spectroscopy (fNIRS) assess resting-state functional connectivity (RSFC) at bedside. We acquired fNIRS data 21 neonates with (postmenstrual age [PMA] = 39.96), in 19 scans were post-therapeutic hypothermia (TH), 20...
A frequently reported limitation to using water as a tracer for measuring CBF has been the dependence of estimate on experimental time (referred failing flow phenomenon, FFP), To eliminate FFP, we have developed adiabatic solution tissue homogeneity model replace single-compartment Kety model. In Part I, derivation was presented, this second part, applied measure in rabbits nuclear magnetic resonance spectroscopy and deuterium oxide, It shown that observable when 2 H clearance data were...
Arterial spin tagging techniques originally used the one-compartment Kety model to describe dynamics of tagged water in brain. The work presented here develops a more realistic that includes contribution capillary bed and accounts for finite time required diffuse across blood-brain barrier. new was evaluate potential errors cerebral blood flow values calculated using model. results predict if is analyze arterial data observed grey matter should be relatively insensitive restricted diffusion...
Quantification of water permeability can improve the accuracy perfusion measurements obtained with arterial spin labeling (ASL) methods, and may provide clinically relevant information regarding functional status microvasculature. The amount labeled in vascular tissue compartments an ASL experiment be estimated based on their distinct diffusion characteristics, turn, determined from relative contributions. In present study, a hybrid magnetic resonance imaging technique was introduced by...
The purpose of this study was to assess if the functional activation caused by painful stimuli could be detected with arterial spin labeling (ASL), which is a non-invasive magnetic resonance imaging (MRI) technique for measuring cerebral blood flow (CBF). Because ASL directly measures flow, it well suited pain conditions that are difficult current MRI, such as chronic pain. However, use in neuroimaging has been hampered its low sensitivity. Recent improvements MRI technology, namely...
Knowledge regarding neural pain processing is primarily the result of studies involving models brief cutaneous pain; however, clinical generally originates in deep tissue and prolonged. This study measured dynamic activation associated with a muscular model incorporating both acute tonic states. Hypertonic saline (5% NaCl) was infused into brachioradialis muscle eleven healthy volunteers for 15min after an initial bolus 0.5mL. Ten controls followed same protocol normal (0.9% NaCl). Magnetic...
Preterm infants are highly susceptible to ischemic brain injury; consequently, continuous bedside monitoring detect ischemia before irreversible damage occurs would improve patient outcome. In addition cerebral blood flow (CBF), assessing the metabolic rate of oxygen (CMRO 2 ) be beneficial considering that thresholds can used evaluate tissue viability. The purpose this study was demonstrate changes in absolute CMRO could measured by combining diffuse correlation spectroscopy (DCS) with...
Obstructive sleep apnea (OSA) subjects show brain injury in sites that control autonomic, cognitive, and mood functions are deficient the condition. The processes contributing to may include altered blood-brain barrier (BBB) actions. Our aim was examine BBB function, based on diffusion-weighted pseudo-continuous arterial spin labeling (DW-pCASL) procedures, OSA compared controls.We performed DW-pCASL imaging nine controls a 3.0-Tesla MRI scanner. Global mean gray white matter transient time...
We present a broad-band, continuous-wave spectral approach to quantify the baseline optical properties of tissue and changes in concentration chromophore, which can assist regional blood flow from dynamic contrast-enhanced near-infrared spectroscopy data. Experiments were conducted on phantoms piglets. The determined by multi-parameter wavelength-dependent data fit photon diffusion equation solution for homogeneous medium. These used find Indocyanine green time course tissue. obtained...
<ns4:p>The search for a “pain centre” in the brain has long eluded neuroscientists. Although many regions of have been shown to respond painful stimuli, all these also other types salient stimuli. In recent paper, Segerdahl <ns4:italic>et al.</ns4:italic> (Nature Neuroscience, 2015) claims that dorsal posterior insula (dpIns) is pain-specific region based on observation magnitude regional cerebral blood flow (rCBF) fluctuations dpIns correlated with evoked pain. However, such conclusion is,...
We investigate a scheme for noninvasive continuous monitoring of absolute cerebral blood flow (CBF) in adult human patients based on combination time-resolved dynamic contrast-enhanced near-infrared spectroscopy (DCE-NIRS) and diffuse correlation (DCS) with semi-infinite head model photon propogation. Continuous CBF is obtained via calibration the DCS index (BFI) by intermittent intravenous injections optical contrast agent indocyanine green. A coefficient (γ) thus determined, permitting...
Coronary artery disease (CAD) poses a risk to the cerebrovascular function of older adults and has been linked impaired cognitive abilities. Using magnetic resonance perfusion imaging, we investigated changes in resting cerebral blood flow (CBF) reactivity (CVR) hypercapnia 34 coronary patients 21 age-matched controls. Gray matter volume images were acquired used as confounding variable separate structure from function. Compared healthy controls, CAD demonstrated reduced CBF superior...
There is a growing interest in the possibility of using functional neuroimaging techniques to aid detecting covert awareness patients who are thought be suffering from disorder consciousness. Immerging optical such as time-resolved near-infrared spectroscopy (TR-fNIRS) ideal for applications due their low-cost, portability, and enhanced sensitivity brain activity. The aim this case study was investigate first time ability TR-fNIRS detect command driven motor imagery (MI) activity...
Diffuse correlation spectroscopy (DCS) is a promising technique for brain monitoring as it can provide continuous signal that directly related to cerebral blood flow (CBF); however, contamination from extracerebral tissue cause underestimations.The goal of this study was investigate whether multi-layered (ML) model accounts light propagation through the different layers could successfully separate scalp and when applied DCS data acquired at multiple source-detector distances.The method first...
The clinical utility of FDG-PET in diagnosing frontotemporal dementia (FTD) has been well demonstrated over the past decades. On contrary, diagnostic value arterial spin labelling (ASL) MRI – a relatively new technique diagnosis FTD yet to be confirmed. Using simultaneous PET/MRI, we evaluated performance ASL identifying pathological abnormalities determine whether can provide similar as FDG-PET. and images were compared 10 patients with healthy older adults. Qualitative quantitative...