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Evidence against pain specificity in the dorsal posterior insula

Karen D. Davis, M. Catherine Bushnell, Gian Domenico Iannetti, Keith St. Lawrence, Robert Coghill
2015 F1000Research  
Davis KD, Bushnell MC, Iannetii GD, St Lawrence K, Coghill R: Evidence against pain specificity in the dorsal posterior insula [version 1; referees: 2 approved].  ... 
doi:10.12688/f1000research.6833.1 pmid:26401267 pmcid:PMC4566284 fatcat:l2d7joh5hrbxnhwbi2kzx7tn2e

Assessing Time-Resolved fNIRS for Brain-Computer Interface Applications of Mental Communication

Androu Abdalmalak, Daniel Milej, Lawrence C. M. Yip, Ali R. Khan, Mamadou Diop, Adrian M. Owen, Keith St. Lawrence
2020 Frontiers in Neuroscience  
Consequently, improved sensitivity to the brain can be achieved by focusing on late-arriving photons (Diop and St Lawrence, 2013; Lange and Tachtsidis, 2019) .  ...  For the time-course shown on the left, which corresponded to the question: "Are you at St. Joseph's Hospital?  ... 
doi:10.3389/fnins.2020.00105 pmid:32132894 pmcid:PMC7040089 fatcat:rtamwvcddbag3el27xmngyaapu

Bolus tracking with nanofilter-based multispectral videography for capturing microvasculature hemodynamics

Mohamadreza Najiminaini, Bozena Kaminska, Keith St. Lawrence, Jeffrey J. L. Carson
2014 Scientific Reports  
Multispectral imaging is a highly desirable modality for material-based analysis in diverse areas such as food production and processing, satellite-based reconnaissance, and biomedical imaging. Here, we present nanofilter-based multispectral videography (nMSV) in the 700 to 950 nm range made possible by the tunable extraordinary-optical-transmission properties of 3D metallic nanostructures. Measurements made with nMSV during a bolus injection of an intravascular tracer in the ear of a piglet
more » ... ulted in spectral videos of the microvasculature. Analysis of the multispectral videos generated contrast measurements representative of arterial pulsation, the distribution of microvascular transit times, as well as a separation of the venous and arterial signals arising from within the tissue. Therefore, nMSV is capable of acquiring serial multispectral images relevant to tissue hemodynamics, which may have application to the detection and identification of skin cancer.
doi:10.1038/srep04737 pmid:24759647 pmcid:PMC3998030 fatcat:n5kebc66zjbfzl34lntjseniou

Monitoring brain temperature by time-resolved near-infrared spectroscopy: pilot study

Mohammad Fazel Bakhsheshi, Mamadou Diop, Keith St. Lawrence, Ting-Yim Lee
2014 Journal of Biomedical Optics  
Mild hypothermia (HT 32°C−33°C ) is an effective neuroprotective strategy for a variety of acute brain injuries. However, the wide clinical adaptation of HT 32−33°C has been hampered by the lack of a reliable noninvasive method for measuring brain temperature, since core measurements have been shown to not always reflect brain temperature. The goal of this work was to develop a noninvasive optical technique for measuring brain temperature that exploits both the temperature dependency of water
more » ... sorption and the high concentration of water in brain (80%-90%). Specifically, we demonstrate the potential of time-resolved near-infrared spectroscopy (TR-NIRS) to measure temperature in tissue-mimicking phantoms (in vitro) and deep brain tissue (in vivo) during heating and cooling, respectively. For deep brain tissue temperature monitoring, experiments were conducted on newborn piglets wherein hypothermia was induced by gradual whole body cooling. Brain temperature was concomitantly measured by TR-NIRS and a thermocouple probe implanted in the brain. Our proposed TR-NIRS method was able to measure the temperature of tissue-mimicking phantoms and brain tissues with a correlation of 0.82 and 0.66 to temperature measured with a thermometer, respectively. The mean difference between the TR-NIRS and thermometer measurements was 0.15°C AE 1.1°C for the in vitro experiments and 0.5°C AE 1.6°C for the in vivo measurements.
doi:10.1117/1.jbo.19.5.057005 pmid:24817622 fatcat:sftxjf6dbffsljloybl5qqyks4

Quantification of blood-brain barrier permeability by dynamic contrast-enhanced NIRS

Daniel Milej, Androu Abdalmalak, Lise Desjardins, Hassaan Ahmed, Ting-Yim Lee, Mamadou Diop, Keith St. Lawrence
2017 Scientific Reports  
St. Lawrence from the Heart and Stroke Foundation, Ontario Provincial Office.  ... 
doi:10.1038/s41598-017-01922-x pmid:28490806 pmcid:PMC5431887 fatcat:6p4rws4jvjaphpbv2i7l2zlmvq

Perfusion and Metabolic Neuromonitoring during Ventricular Taps in Infants with Post-Hemorrhagic Ventricular Dilatation

Ajay Rajaram, Lawrence C. M. Yip, Daniel Milej, Marianne Suwalski, Matthew Kewin, Marcus Lo, Jeffrey J. L. Carson, Victor Han, Soume Bhattacharya, Mamadou Diop, Sandrine de Ribaupierre, Keith St. Lawrence
2020 Brain Sciences  
Post-hemorrhagic ventricular dilatation (PHVD) is characterized by a build-up of cerebral spinal fluid (CSF) in the ventricles, which increases intracranial pressure and compresses brain tissue. Clinical interventions (i.e., ventricular taps, VT) work to mitigate these complications through CSF drainage; however, the timing of these procedures remains imprecise. This study presents Neonatal NeuroMonitor (NNeMo), a portable optical device that combines broadband near-infrared spectroscopy
more » ... ) and diffuse correlation spectroscopy (DCS) to provide simultaneous assessments of cerebral blood flow (CBF), tissue saturation (StO2), and the oxidation state of cytochrome c oxidase (oxCCO). In this study, NNeMo was used to monitor cerebral hemodynamics and metabolism in PHVD patients selected for a VT. Across multiple VTs in four patients, no significant changes were found in any of the three parameters: CBF increased by 14.6 ± 37.6% (p = 0.09), StO2 by 1.9 ± 4.9% (p = 0.2), and oxCCO by 0.4 ± 0.6 µM (p = 0.09). However, removing outliers resulted in significant, but small, increases in CBF (6.0 ± 7.7%) and oxCCO (0.1 ± 0.1 µM). The results of this study demonstrate NNeMo's ability to provide safe, non-invasive measurements of cerebral perfusion and metabolism for neuromonitoring applications in the neonatal intensive care unit.
doi:10.3390/brainsci10070452 pmid:32679665 fatcat:x26zmzelfvdjvidrswcqiul4ly

Subtraction-based approach for enhancing the depth sensitivity of time-resolved NIRS

Daniel Milej, Androu Abdalmalak, Peter McLachlan, Mamadou Diop, Adam Liebert, Keith. St. Lawrence
2016 Biomedical Optics Express  
St. Lawrence from the Heart and Stroke Foundation, Ontario Provincial Office.  ... 
doi:10.1364/boe.7.004514 pmid:27895992 pmcid:PMC5119592 fatcat:bkqufigumrfsjexcp4wtwtw3lq

Turbo-FLASH Based Arterial Spin Labeled Perfusion MRI at 7 T

Zhentao Zuo, Rui Wang, Yan Zhuo, Rong Xue, Keith S. St. Lawrence, Danny J. J. Wang, Xiaoliang Zhang
2013 PLoS ONE  
Motivations of arterial spin labeling (ASL) at ultrahigh magnetic fields include prolonged blood T 1 and greater signal-tonoise ratio (SNR). However, increased B 0 and B 1 inhomogeneities and increased specific absorption ratio (SAR) challenge practical ASL implementations. In this study, Turbo-FLASH (Fast Low Angle Shot) based pulsed and pseudo-continuous ASL sequences were performed at 7T, by taking advantage of the relatively low SAR and short TE of Turbo-FLASH that minimizes susceptibility
more » ... rtifacts. Consistent with theoretical predictions, the experimental data showed that Turbo-FLASH based ASL yielded approximately 4 times SNR gain at 7T compared to 3T. High quality perfusion images were obtained with an inplane spatial resolution of 0.8561.7 mm 2 . A further functional MRI study of motor cortex activation precisely located the primary motor cortex to the precentral gyrus, with the same high spatial resolution. Finally, functional connectivity between left and right motor cortices as well as supplemental motor area were demonstrated using resting state perfusion images. Turbo-FLASH based ASL is a promising approach for perfusion imaging at 7T, which could provide novel approaches to high spatiotemporal resolution fMRI and to investigate the functional connectivity of brain networks at ultrahigh field.
doi:10.1371/journal.pone.0066612 pmid:23818950 pmcid:PMC3688599 fatcat:qcyxesofazcsjpotrf2grlgq2q

Improving the depth sensitivity of time-resolved measurements by extracting the distribution of times-of-flight

Mamadou Diop, Keith St. Lawrence
2013 Biomedical Optics Express  
St. Lawrence, "Time-resolved nearinfrared technique for bedside monitoring of absolute cerebral blood flow," Proc. SPIE 7555, 75550Z (2010). 29. V. Ntziachristos, X. Ma, A. G. Yodh, and B.  ...  Two series of TPSFs were acquired at an integration time of 0.4 s for 5 min, each following a rapid intravenous injection of an ICG bolus (0.1 mg/kg, Sigma-Aldrich, St. Louis, MO).  ... 
doi:10.1364/boe.4.000447 pmid:23504445 pmcid:PMC3595088 fatcat:3di7blrsx5h4ffyfkcryrrtiom

Direct assessment of extracerebral signal contamination on optical measurements of cerebral blood flow, oxygenation, and metabolism

Daniel Milej, Androu Abdalmalak, Ajay Rajaram, Keith St. Lawrence
2020 Neurophotonics  
., Toronto, Canada) was used to control P ET CO 2 , and subjects were required to wear a mask that was sealed by a transparent film dressing (Tegaderm™, 3M, St. Paul, United States) (Fig. 2) .  ...  Keith St. Lawrence is an associate professor in the Department of Medical Biophysics at Western University.  ... 
doi:10.1117/1.nph.7.4.045002 pmid:33062801 pmcid:PMC7540337 fatcat:uebpguipnzcuhiipp2oibsum3e

Single-session communication with a locked-in patient by functional near-infrared spectroscopy

Androu Abdalmalak, Daniel Milej, Loretta Norton, Derek B. Debicki, Teneille Gofton, Mamadou Diop, Adrian M. Owen, Keith St. Lawrence
2017 Neurophotonics  
Single-session communication with a locked-in patient by functional near-infrared spectroscopy," Abstract. There is a growing interest in the possibility of using functional neuroimaging techniques to aid in detecting covert awareness in patients who are thought to be suffering from a disorder of consciousness. Immerging optical techniques such as time-resolved functional nearinfrared spectroscopy (TR-fNIRS) are ideal for such applications due to their low-cost, portability, and enhanced
more » ... vity to brain activity. The aim of this case study was to investigate for the first time the ability of TR-fNIRS to detect command driven motor imagery (MI) activity in a functionally locked-in patient suffering from Guillain-Barré syndrome. In addition, the utility of using TR-fNIRS as a brain-computer interface (BCI) was also assessed by instructing the patient to perform an MI task as affirmation to three questions: (1) confirming his last name, (2) if he was in pain, and (3) if he felt safe. At the time of this study, the patient had regained limited eye movement, which provided an opportunity to accurately validate a BCI after the fNIRS study was completed. Comparing the two sets of responses showed that fNIRS provided the correct answers to all of the questions. These promising results demonstrate for the first time the potential of using an MI paradigm in combination with fNIRS to communicate with functionally locked-in patients without the need for prior training.
doi:10.1117/1.nph.4.4.040501 pmid:29296627 pmcid:PMC5741990 fatcat:ebqlemtdgzhjdarlw6tlgpmud4

Impaired Cerebrovascular Function in Coronary Artery Disease Patients and Recovery Following Cardiac Rehabilitation

Udunna C. Anazodo, J. K. Shoemaker, Neville Suskin, Tracy Ssali, Danny J. J. Wang, Keith S. St. Lawrence
2016 Frontiers in Aging Neuroscience  
The CAD group comprised of individuals with clinical diagnosis for CAD including acute coronary syndromes such as ST elevation and non-ST elevation myocardial infarct, and angina pectoris confirmed by  ...  A 2D transthoracic Doppler echocardiogram (Vingmed System FiVe, GE Healthcare, Chalfont St Giles, UK) was performed to assess left ventricular ejection fraction -a clinical index of cardiac function.  ...  Copyright © 2016 Anazodo, Shoemaker, Suskin, Ssali, Wang and St. Lawrence. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).  ... 
doi:10.3389/fnagi.2015.00224 pmid:26779011 pmcid:PMC4700211 fatcat:fpodg6ftfrd23di4bcim4uzfau

Mapping Long-Term Functional Changes in Cerebral Blood Flow by Arterial Spin Labeling

Tracy Ssali, Udunna C. Anazodo, Yves Bureau, Bradley J. MacIntosh, Matthias Günther, Keith St. Lawrence, Kewei Chen
2016 PLoS ONE  
Although arterial spin labeling (ASL) is appealing for mapping long-term changes in functional activity, inter-sessional variations in basal blood flow, arterial transit times (ATTs), and alignment errors, can result in significant false activation when comparing images from separate sessions. By taking steps to reduce these sources of noise, this study assessed the ability of ASL to detect functional CBF changes between sessions. ASL data were collected in three sessions to image ATT, resting
more » ... BF and CBF changes associated with motor activation (7 participants). Activation maps were generated using rest and task images acquired in the same session and from sessions separated by up to a month. Good agreement was found when comparing between-session activation maps to within-session activation maps with only a 16% decrease in precision (within-session: 90 ± 7%) and a 13% decrease in the Dice similarity (within-session: 0.75 ± 0.07) coefficient after a month. In addition, voxel-wise reproducibility (within-session: 4.7 ± 4.5%) and reliability (within-session: 0.89 ± 0.20) of resting grey-matter CBF decreased by less than 18% for the betweensession analysis relative to within-session values. ATT variability between sessions (5.0 ± 2.7%) was roughly half the between-subject variability, indicating that its effects on longitudinal CBF were minimal. These results demonstrate that conducting voxel-wise analysis on CBF images acquired on different days is feasible with only modest loss in precision, highlighting the potential of ASL for longitudinal studies.
doi:10.1371/journal.pone.0164112 pmid:27706218 pmcid:PMC5051683 fatcat:ei7plnntfbf4jf2mf724jeipka

Potential for photoacoustic imaging of the neonatal brain

Pantea Tavakolian, Ivan Kosik, Astrid Chamson-Reig, Keith St. Lawrence, Jeffrey J. L. Carson, Alexander A. Oraevsky, Lihong V. Wang
2013 Photons Plus Ultrasound: Imaging and Sensing 2013  
Photoacoustic imaging is a hybrid imaging technique that combines many of the merits of both optical and ultrasound imaging. Photoacoustic imaging (PAI) has been hypothesized as a technique for imaging neonatal brain. However, PAI of the brain is more challenging than traditional methods (e.g. near infrared spectroscopy) due to the presence of the skull layer. To evaluate the potential limits the skull places on 3D PAI of the neonatal brain, we constructed a neonatal skull phantom (~1.52-mm
more » ... k) with a mixture of epoxy and titanium dioxide powder that provided acoustic insertion loss (1-5MHz) similar to human infant skull bone. The phantom was molded into a realistic infant skull shape by means of a CNCmachined mold that was based upon a 3D CAD model. Then, propagation of photoacoustic (PA) signals through the skull phantom was examined. A photoacoustic point source was raster-scanned within the imaging cavity of a 128-channel PAI system to capture the imaging operator with and without the intervening skull phantom layer. Then, effects of the skull phantom on PA signals and consequently on PA images was evaluated in detail. We captured 3D photoacoustic images of tubes filled with indocyanine green (ICG). The system was capable of reconstructing an image of a tube filled with 50 µM ICG in presence of the skull. Image processing method was developed to correct photoacoustic images from the effects of the skull. The method was tested on an image of an object captured through the skull, which demonstrated that the effects of the skull on PA images are predictable and modifiable.
doi:10.1117/12.2005453 fatcat:q4e3mudgbjeuthl2yfhovdfiie

Development of a stand-alone DCS system for monitoring absolute cerebral blood flow

Mahro Khalid, Daniel Milej, Ajay Rajaram, Androu Abdalmalak, Laura Morrison, Mamadou Diop, Keith St. Lawrence
2019 Biomedical Optics Express  
Diffuse correlation spectroscopy (DCS) is a noninvasive optical technique for monitoring cerebral blood flow (CBF). This work presents a stand-alone DCS system capable of monitoring absolute CBF by incorporating a quantitative dynamic contrast-enhanced (DCE) technique. Multi-distance data were acquired to measure the tissue optical properties and to perform DCE experiments. Feasibility of the technique was assessed in piglets in which the optical properties were measured independently by
more » ... solved near-infrared spectroscopy. A strong linear correlation was observed between CBF values derived using the two sets of optical properties, demonstrating that this hybrid DCS approach can provide real-time monitoring of absolute CBF.
doi:10.1364/boe.10.004607 pmid:31565512 pmcid:PMC6757462 fatcat:pz23bryzffch7k36d6ti5skuse
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