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Favilla CG, Carter S, Hartl B, Gitlevich R, Mullen MT, Yodh AG, Baker WB, Konecky S. Validation of the Openwater wearable optical system: cerebral hemodynamic monitoring during a breath hold maneuver. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.10.11.23296612. [PMID: 37873126 PMCID: PMC10592983 DOI: 10.1101/2023.10.11.23296612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Bedside cerebral blood flow (CBF) monitoring has the potential to inform and improve care for acute neurologic diseases, but technical challenges limit the use of existing techniques in clinical practice. Here we validate the Openwater optical system, a novel wearable headset that uses laser speckle contrast to monitor microvascular hemodynamics. We monitored 25 healthy adults with the Openwater system and concurrent transcranial Doppler (TCD) while performing a breath-hold maneuver to increase CBF. Relative blood flow (rBF) was derived from the changes in speckle contrast, and relative blood volume (rBV) was derived from the changes in speckle average intensity. A strong correlation was observed between beat-to-beat optical rBF and TCD-measured cerebral blood flow velocity (CBFv), R=0.79; the slope of the linear fit indicates good agreement, 0.87 (95% CI:0.83-0.92). Beat-to-beat rBV and CBFv were strongly correlated, R=0.72, but as expected the two variables were not proportional; changes in rBV were smaller than CBFv changes, with linear fit slope of 0.18 (95% CI:0.17-0.19). Further, strong agreement was found between rBF and CBFv waveform morphology and related metrics. This first in vivo validation of the Openwater optical system highlights its potential as a cerebral hemodynamic monitor, but additional validation is needed in disease states.
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Ziółkowski A, Pudełko A, Kazimierska A, Uryga A, Czosnyka Z, Kasprowicz M, Czosnyka M. Peak appearance time in pulse waveforms of intracranial pressure and cerebral blood flow velocity. Front Physiol 2023; 13:1077966. [PMID: 36685171 PMCID: PMC9846027 DOI: 10.3389/fphys.2022.1077966] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 12/08/2022] [Indexed: 01/05/2023] Open
Abstract
The shape of the pulse waveforms of intracranial pressure (ICP) and cerebral blood flow velocity (CBFV) typically contains three characteristic peaks. It was reported that alterations in cerebral hemodynamics may influence the shape of the pulse waveforms by changing peaks' configuration. However, the changes in peak appearance time (PAT) in ICP and CBFV pulses are only described superficially. We analyzed retrospectively ICP and CBFV signals recorded in traumatic brain injury patients during decrease in ICP induced by hypocapnia (n = 11) and rise in ICP during episodes of ICP plateau waves (n = 8). All three peaks were manually annotated in over 48 thousand individual pulses. The changes in PAT were compared between periods of vasoconstriction (expected during hypocapnia) and vasodilation (expected during ICP plateau waves) and their corresponding baselines. Correlation coefficient (rS) analysis between mean ICP and mean PATs was performed in each individual recording. Vasodilation prolonged PAT of the first peaks of ICP and CBFV pulses and the third peak of CBFV pulse. It also accelerated PAT of the third peak of ICP pulse. In contrast, vasoconstriction shortened appearance time of the first peaks of ICP and CBFV pulses and the second peak of ICP pulses. Analysis of individual recordings demonstrated positive association between changes in PAT of all three peaks in the CBFV pulse and mean ICP (rS range: 0.32-0.79 for significant correlations). Further study is needed to test whether PAT of the CBFV pulse may serve as an indicator of changes in ICP-this may open a perspective for non-invasive monitoring of alterations in mean ICP.
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Affiliation(s)
- Arkadiusz Ziółkowski
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Agata Pudełko
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Agnieszka Kazimierska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Agnieszka Uryga
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Zofia Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke’s Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Magdalena Kasprowicz
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland,*Correspondence: Magdalena Kasprowicz,
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke’s Hospital, University of Cambridge, Cambridge, United Kingdom,Institute of Electronic Systems, Faculty of Electronics and Information Technology, Warsaw University of Technology, Warsaw, Poland
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Whittaker JR, Fasano F, Venzi M, Liebig P, Gallichan D, Möller HE, Murphy K. Measuring Arterial Pulsatility With Dynamic Inflow Magnitude Contrast. Front Neurosci 2022; 15:795749. [PMID: 35110991 PMCID: PMC8802674 DOI: 10.3389/fnins.2021.795749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/22/2021] [Indexed: 11/13/2022] Open
Abstract
The pulsatility of blood flow through cerebral arteries is clinically important, as it is intrinsically associated with cerebrovascular health. In this study we outline a new MRI approach to measuring the real-time pulsatile flow in cerebral arteries, which is based on the inflow phenomenon associated with fast gradient-recalled-echo acquisitions. Unlike traditional phase-contrast techniques, this new method, which we dub dynamic inflow magnitude contrast (DIMAC), does not require velocity-encoding gradients as sensitivity to flow velocity is derived purely from the inflow effect. We achieved this using a highly accelerated single slice EPI acquisition with a very short TR (15 ms) and a 90° flip angle, thus maximizing inflow contrast. We simulate the spoiled GRE signal in the presence of large arteries and perform a sensitivity analysis. The sensitivity analysis demonstrates that in the regime of high inflow contrast, DIMAC shows much greater sensitivity to flow velocity over blood volume changes. We support this theoretical prediction with in-vivo data collected in two separate experiments designed to demonstrate the utility of the DIMAC signal contrast. We perform a hypercapnia challenge experiment in order to experimentally modulate arterial tone within subjects, and thus modulate the arterial pulsatile flow waveform. We also perform a thigh-cuff release challenge, designed to induce a transient drop in blood pressure, and demonstrate that the continuous DIMAC signal captures the complex transient change in the pulsatile and non-pulsatile components of flow. In summary, this study proposes a new role for a well-established source of MR image contrast and demonstrates its potential for measuring both steady-state and dynamic changes in arterial tone.
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Affiliation(s)
- Joseph R. Whittaker
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | | | - Marcello Venzi
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
| | | | | | - Harald E. Möller
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Kevin Murphy
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
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Afkhami R, Walker FR, Ramadan S, Wong R, Johnson SJ. Indexing cerebrovascular health using near-infrared spectroscopy. Sci Rep 2021; 11:14812. [PMID: 34285338 PMCID: PMC8292377 DOI: 10.1038/s41598-021-94348-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 07/05/2021] [Indexed: 12/01/2022] Open
Abstract
Near-infrared spectroscopy (NiRS) is a relatively new technology of brain imaging with its potential in the assessment of cerebrovascular health only recently discovered. Encouraging early results suggest that NiRS can be used as an inexpensive and portable cerebrovascular health tracking device using a recently proposed pulse relaxation function (PReFx). In this paper, we propose a new NiRS timing index, \documentclass[12pt]{minimal}
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\begin{document}$$\text {TI}_{\rm NiRS}$$\end{document}TINiRS, of cerebrovascular health. \documentclass[12pt]{minimal}
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\begin{document}$$\text {TI}_{\rm NiRS}$$\end{document}TINiRS is a novel use of the NiRS technology. \documentclass[12pt]{minimal}
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\begin{document}$$\text {TI}_{\rm NiRS}$$\end{document}TINiRS is motivated by the previously proved relationship of the timing of the reflected wave with vascular resistance and compliance in the context of pressure waveforms. We correlated both \documentclass[12pt]{minimal}
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\begin{document}$$\text {TI}_{\rm NiRS}$$\end{document}TINiRS and PReFx against age, a non-exercise cardiorespiratory fitness (CRF) index, and two existing indices of cerebrovascular health, namely transcranial Doppler (TCD) augmentation index, \documentclass[12pt]{minimal}
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\begin{document}$$\text {AI}_{\rm TCD}$$\end{document}AITCD, and magnetic resonance imaging (MRI) blood flow pulsatility index, \documentclass[12pt]{minimal}
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\begin{document}$$\text {PI}_{\rm MRI}$$\end{document}PIMRI. The \documentclass[12pt]{minimal}
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\begin{document}$$\text {TI}_{\rm NiRS}$$\end{document}TINiRS correlations with Age, CRF, \documentclass[12pt]{minimal}
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\begin{document}$$\text {PI}_{\rm MRI}$$\end{document}PIMRI and \documentclass[12pt]{minimal}
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\begin{document}$$\text {AI}_{\rm TCD}$$\end{document}AITCD all are significant, i.e., \documentclass[12pt]{minimal}
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\begin{document}$$r=0.53$$\end{document}r=0.53 (\documentclass[12pt]{minimal}
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\begin{document}$$r=-0.44$$\end{document}r=-0.44 (\documentclass[12pt]{minimal}
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\begin{document}$$p=0.011$$\end{document}p=0.011), \documentclass[12pt]{minimal}
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\begin{document}$$p=0.012$$\end{document}p=0.012) and \documentclass[12pt]{minimal}
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\begin{document}$$p=0.010$$\end{document}p=0.010), respectively. PReFx, however, did not have significant correlations with any of the vascular health factors. The proposed timing index is a reliable indicator of cerebrovascular aging factors in the NiRS waveform.
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Affiliation(s)
- Rashid Afkhami
- School of Engineering, University of Newcastle, Callaghan, Australia.
| | - Frederick R Walker
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
| | - Saadallah Ramadan
- School of Health Sciences, University of Newcastle, Callaghan, Australia
| | - Rachel Wong
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
| | - Sarah J Johnson
- School of Engineering, University of Newcastle, Callaghan, Australia
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Ruediger SL, Koep JL, Keating SE, Pizzey FK, Coombes JS, Bailey TG. Effect of menopause on cerebral artery blood flow velocity and cerebrovascular reactivity: Systematic review and meta-analysis. Maturitas 2021; 148:24-32. [PMID: 34024348 DOI: 10.1016/j.maturitas.2021.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/28/2021] [Accepted: 04/11/2021] [Indexed: 12/31/2022]
Abstract
BACKGROUND Menopause and its associated decline in oestrogen is linked to chronic conditions like cardiovascular disease and osteoporosis, which may be difficult to disentangle from the effects of ageing. Further, post-menopausal women are at increased risk of cerebrovascular disease, linked to declines in cerebral blood flow (CBF) and cerebrovascular reactivity (CVR), yet the direct understanding of the impact of the menopause on cerebrovascular function is unclear. The aim of this systematic review and meta-analysis was to examine the literature investigating CBF and CVR in pre- compared with post-menopausal women METHODS: Five databases were searched for studies assessing CBF or CVR in pre- and post-menopausal women. Meta-analysis examined the effect of menopausal status on middle cerebral artery velocity (MCAv), and GRADE-assessed evidence certainty RESULTS: Nine studies (n=504) included cerebrovascular outcomes. Six studies (n=239) reported negligible differences in MCAv between pre- and post-menopausal women [2.11cm/s (95% CI: -8.94 to 4.73, p=0.54)], but with a "low" certainty of evidence. MCAv was lower in post-menopausal women in two studies, when MCAv was adjusted for blood pressure. CVR was lower in post- compared with pre-menopausal women in two of three studies, but high-quality evidence is lacking. Across outcomes, study methodology and reporting criteria for menopause were inconsistent CONCLUSIONS: MCAv was similar in post- compared with pre-menopausal women. Methodological differences in characterising menopause and inconsistent reporting of cerebrovascular outcomes make comparisons difficult. Comprehensive assessments of cerebrovascular function of the intra- and extracranial arteries to determine the physiological implications of menopause on CBF with healthy ageing is warranted.
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Affiliation(s)
- Stefanie L Ruediger
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health; School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Jodie L Koep
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health; School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, QLD, Australia; Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Shelley E Keating
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health; School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Faith K Pizzey
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health; School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Jeff S Coombes
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health; School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Tom G Bailey
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health; School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, QLD, Australia; School of Nursing, Midwifery and Social Work, The University of Queensland, Brisbane, QLD, Australia
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Thorpe SG, Thibeault CM, Canac N, Jalaleddini K, Dorn A, Wilk SJ, Devlin T, Scalzo F, Hamilton RB. Toward automated classification of pathological transcranial Doppler waveform morphology via spectral clustering. PLoS One 2020; 15:e0228642. [PMID: 32027714 PMCID: PMC7004309 DOI: 10.1371/journal.pone.0228642] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 01/20/2020] [Indexed: 11/21/2022] Open
Abstract
Cerebral Blood Flow Velocity waveforms acquired via Transcranial Doppler (TCD) can provide evidence for cerebrovascular occlusion and stenosis. Thrombolysis in Brain Ischemia (TIBI) flow grades are widely used for this purpose, but require subjective assessment by expert evaluators to be reliable. In this work we seek to determine whether TCD morphology can be objectively assessed using an unsupervised machine learning approach to waveform categorization. TCD beat waveforms were recorded at multiple depths from the Middle Cerebral Arteries of 106 subjects; 33 with Large Vessel Occlusion (LVO). From each waveform, three morphological features were extracted, quantifying onset of maximal velocity, systolic canopy length, and the number/prominence of peaks/troughs. Spectral clustering identified groups implicit in the resultant three-dimensional feature space, with gap statistic criteria establishing the optimal cluster number. We found that gap statistic disparity was maximized at four clusters, referred to as flow types I, II, III, and IV. Types I and II were primarily composed of control subject waveforms, whereas types III and IV derived mainly from LVO patients. Cluster morphologies for types I and IV aligned clearly with Normal and Blunted TIBI flows, respectively. Types II and III represented commonly observed flow-types not delineated by TIBI, which nonetheless deviate from normal and blunted flows. We conclude that important morphological variability exists beyond that currently quantified by TIBI in populations experiencing or at-risk for acute ischemic stroke, and posit that the observed flow-types provide the foundation for objective methods of real-time automated flow type classification.
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Affiliation(s)
- Samuel G. Thorpe
- Department of Research, Neural Analytics, Inc., Los Angeles, California, United States of America
- * E-mail:
| | - Corey M. Thibeault
- Department of Research, Neural Analytics, Inc., Los Angeles, California, United States of America
| | - Nicolas Canac
- Department of Research, Neural Analytics, Inc., Los Angeles, California, United States of America
| | - Kian Jalaleddini
- Department of Research, Neural Analytics, Inc., Los Angeles, California, United States of America
| | - Amber Dorn
- Department of Research, Neural Analytics, Inc., Los Angeles, California, United States of America
| | - Seth J. Wilk
- Department of Research, Neural Analytics, Inc., Los Angeles, California, United States of America
| | - Thomas Devlin
- Department of Neurology, Erlanger Medical Center, Chattanooga, Tennessee, United States of America
| | - Fabien Scalzo
- Department of Neurology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Robert B. Hamilton
- Department of Research, Neural Analytics, Inc., Los Angeles, California, United States of America
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7
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Cerebral and peripheral vascular differences between pre- and postmenopausal women. ACTA ACUST UNITED AC 2020; 27:170-182. [DOI: 10.1097/gme.0000000000001442] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Jalaleddini K, Canac N, Thorpe SG, O'Brien MJ, Ranjbaran M, Delay B, Dorn AY, Scalzo F, Thibeault CM, Wilk SJ, Hamilton RB. Objective Assessment of Beat Quality in Transcranial Doppler Measurement of Blood Flow Velocity in Cerebral Arteries. IEEE Trans Biomed Eng 2019; 67:883-892. [PMID: 31217091 DOI: 10.1109/tbme.2019.2923146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Transcranial Doppler (TCD) ultrasonography measures pulsatile cerebral blood flow velocity in the arteries and veins of the head and neck. Similar to other real-time measurement modalities, especially in healthcare, the identification of high-quality signals is essential for clinical interpretation. Our goal is to identify poor quality beats and remove them prior to further analysis of the TCD signal. METHODS We selected objective features for this purpose including Euclidean distance between individual and average beat waveforms, cross-correlation between individual and average beat waveforms, ratio of the high-frequency power to the total beat power, beat length, and variance of the diastolic portion of the beat waveform. We developed an iterative outlier detection algorithm to identify and remove the beats that are different from others in a recording. Finally, we tested the algorithm on a dataset consisting of more than 15 h of TCD data recorded from 48 stroke and 34 in-hospital control subjects. RESULTS We assessed the performance of the algorithm in the improvement of estimation of clinically important TCD parameters by comparing them to that of manual beat annotation. The results show that there is a strong correlation between the two, that demonstrates the algorithm has successfully recovered the clinically important features. We obtained significant improvement in estimating the TCD parameters using the algorithm accepted beats compared to using all beats. SIGNIFICANCE Our algorithm provides a valuable tool to clinicians for automated detection of the reliable portion of the data. Moreover, it can be used as a pre-processing tool to improve the data quality for automated diagnosis of pathologic beat waveforms using machine learning.
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Thorpe SG, Thibeault CM, Canac N, Wilk SJ, Devlin T, Hamilton RB. Decision Criteria for Large Vessel Occlusion Using Transcranial Doppler Waveform Morphology. Front Neurol 2018; 9:847. [PMID: 30386287 PMCID: PMC6199366 DOI: 10.3389/fneur.2018.00847] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 09/21/2018] [Indexed: 01/23/2023] Open
Abstract
Background: The current lack of effective tools for prehospital identification of Large Vessel Occlusion (LVO) represents a significant barrier to efficient triage of stroke patients and detriment to treatment efficacy. The validation of objective Transcranial Doppler (TCD) metrics for LVO detection could provide first responders with requisite tools for informing stroke transfer decisions, dramatically improving patient care. Objective: To compare the diagnostic efficacy of two such candidate metrics: Velocity Asymmetry Index (VAI), which quantifies disparity of blood flow velocity across the cerebral hemispheres, and Velocity Curvature Index (VCI), a recently proposed TCD morphological biomarker. Additionally, we investigate a simple decision tree combining both metrics. Methods: We retrospectively compare accuracy/sensitivity/specificity (ACC/SEN/SPE) of each method (relative to standard CT-Angiography) in detecting LVO in a population of 66 subjects presenting with stroke symptoms (33 with CTA-confirmed LVO), enrolled consecutively at Erlanger Southeast Regional Stroke Center in Chattanooga, TN. Results: Individual VCI and VAI metrics demonstrated robust performance, with area under receiver operating characteristic curve (ROC-AUC) of 94% and 88%, respectively. Additionally, leave-one-out cross-validation at optimal identified thresholds resulted in 88% ACC (88% SEN) for VCI, vs. 79% ACC (76% SEN) for VAI. When combined, the resultant decision tree achieved 91% ACC (94% SEN). Discussion: We conclude VCI to be superior to VAI for LVO detection, and provide evidence that simple decision criteria incorporating both metrics may further optimize. Performance: Our results suggest that machine-learning approaches to TCD morphological analysis may soon enable robust prehospital LVO identification. Registration: Was not required for this feasibility study.
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Affiliation(s)
| | | | - Nicolas Canac
- Neural Analytics, Inc., Los Angeles, CA, United States
| | - Seth J Wilk
- Neural Analytics, Inc., Los Angeles, CA, United States
| | - Thomas Devlin
- Erlanger Medical Center, Chattanooga, TN, United States
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Thorpe SG, Thibeault CM, Wilk SJ, O'Brien M, Canac N, Ranjbaran M, Devlin C, Devlin T, Hamilton RB. Velocity Curvature Index: a Novel Diagnostic Biomarker for Large Vessel Occlusion. Transl Stroke Res 2018; 10:475-484. [PMID: 30293170 PMCID: PMC6733810 DOI: 10.1007/s12975-018-0667-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 08/06/2018] [Accepted: 09/24/2018] [Indexed: 11/25/2022]
Abstract
Despite being a conveniently portable technology for stroke assessment, Transcranial Doppler ultrasound (TCD) remains widely underutilized due to complex training requirements necessary to reliably obtain and interpret cerebral blood flow velocity (CBFV) waveforms. The validation of objective TCD metrics for large vessel occlusion (LVO) represents a first critical step toward enabling use by less formally trained personnel. In this work, we assess the diagnostic utility, relative to current standard CT angiography (CTA), of a novel TCD-derived biomarker for detecting LVO. Patients admitted to the hospital with stroke symptoms underwent TCD screening and were grouped into LVO and control groups based on the presence of CTA confirmed occlusion. Velocity curvature index (VCI) was computed from CBFV waveforms recorded at multiple depths from the middle cerebral arteries (MCA) of both cerebral hemispheres. VCI was assessed for 66 patients, 33 of which had occlusions of the MCA or internal carotid artery. Our results show that VCI was more informative when measured from the cerebral hemisphere ipsilateral to the site of occlusion relative to contralateral. Moreover, given any pair of bilateral recordings, VCI separated LVO patients from controls with average area under receiver operating characteristic curve of 92%, which improved to greater than 94% when pairs were selected by maximal velocity. We conclude that VCI is an analytically valid candidate biomarker for LVO diagnosis, possessing comparable accuracy, and several important advantages, relative to current TCD diagnostic methodologies.
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Affiliation(s)
- Samuel G Thorpe
- Neural Analytics, Inc., 2440 S. Sepulveda Blvd. Suite 115, Los Angeles, CA, 90064, USA.
| | - Corey M Thibeault
- Neural Analytics, Inc., 2440 S. Sepulveda Blvd. Suite 115, Los Angeles, CA, 90064, USA
| | - Seth J Wilk
- Neural Analytics, Inc., 2440 S. Sepulveda Blvd. Suite 115, Los Angeles, CA, 90064, USA
| | - Michael O'Brien
- Neural Analytics, Inc., 2440 S. Sepulveda Blvd. Suite 115, Los Angeles, CA, 90064, USA
| | - Nicolas Canac
- Neural Analytics, Inc., 2440 S. Sepulveda Blvd. Suite 115, Los Angeles, CA, 90064, USA
| | - Mina Ranjbaran
- Neural Analytics, Inc., 2440 S. Sepulveda Blvd. Suite 115, Los Angeles, CA, 90064, USA
| | - Christian Devlin
- Cardiac Biomechanics Group, University of Virginia, Charlottesville, VA, USA
| | - Thomas Devlin
- Department of Neurology, Erlanger Medical Center, Chattanooga, TN, USA
| | - Robert B Hamilton
- Neural Analytics, Inc., 2440 S. Sepulveda Blvd. Suite 115, Los Angeles, CA, 90064, USA
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Curry BH, Bond V, Pemminati S, Gorantla VR, Volkova YA, Kadur K, Millis RM. Effects of a Dietary Beetroot Juice Treatment on Systemic and Cerebral Haemodynamics- A Pilot Study. J Clin Diagn Res 2016; 10:CC01-5. [PMID: 27630836 DOI: 10.7860/jcdr/2016/20049.8113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/07/2016] [Indexed: 11/24/2022]
Abstract
INTRODUCTION Beetroot Juice (BJ) contains dietary nitrates that increase the blood Nitric Oxide (NO) level, decrease Blood Pressure (BP), increase athletic performance and improve cognitive functions but the mechanism remains unclear. Ultrasonographic measurement of middle cerebral artery blood flow velocity with computation of Cerebral Augmentation Index (CAIx) is a measure of the reflected flow signal, modulated by changes in cerebrovascular resistance and compliance. AIM This pilot study tests the hypothesis that ingestion of an amount of BJ sufficient to raise the blood NO level two-to three-fold, decreases Transcranial Doppler (TCD) measured CAIx. MATERIALS AND METHODS Ten healthy young-adult African-American women were studied at two levels of submaximal exercise, 40% and 80% of their predetermined peak oxygen consumptions. The subjects ingested nitrate-free orange juice (OJ, control) and an isocaloric BJ beverage (1.5 mg/mL nitrate, 220 Cal), on different days, 1-2 weeks apart. RESULTS The BJ treatment increased blood NO and decreased systolic BP at rest and at the two levels of exercise. The BJ treatment decreased CAIx only at the two levels of exercise (from 79 ± 2% to 62 ± 2% and from 80 ± 2% to 60 ± 3%, p<0.05). Exercise increased TCD-measured resistance and pulsatility indices (RIx, PIx) without changing AIx. The BJ treatment had no effect on RIx and PIx. CONCLUSION These findings suggest that decreased CAIx associated with aerobic exercise reflects the change in cerebral haemodynamics resulting from dietary nitrate supplementation. Future studies should determine whether the BJ-induced decrement in CAIx is correlated with an improvement in brain function.
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Affiliation(s)
- Bryan Heath Curry
- Professor, Department of Medicine, Division of Cardiology, Howard University College of Medicine and Howard University Hospital , Washington, DC 20060, United States of America
| | - Vernon Bond
- Professor, Department of Recreation, Human Performance and Leisure Studies and Exercise Science and Human Nutrition Laboratory, Howard University Cancer Centre , Washington, DC 20060, United States of America
| | - Sudhakar Pemminati
- Associate Professor, Department of Medical Pharmacology, AUA College of Medicine and Manipal University , Antigua
| | - Vasavi Rakesh Gorantla
- Assistant Professor, Department of Behavioural Sciences and Neuroscience, AUA College of Medicine , Antigua
| | | | - Kishan Kadur
- Assistant Professor, Department of Medical Physiology, AUA College of Medicine , Antigua
| | - Richard Mark Millis
- Professor, Department of Medical Physiology, AUA College of Medicine , Antigua
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Flück D, Beaudin AE, Steinback CD, Kumarpillai G, Shobha N, McCreary CR, Peca S, Smith EE, Poulin MJ. Effects of aging on the association between cerebrovascular responses to visual stimulation, hypercapnia and arterial stiffness. Front Physiol 2014; 5:49. [PMID: 24600398 PMCID: PMC3928624 DOI: 10.3389/fphys.2014.00049] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 01/26/2014] [Indexed: 02/04/2023] Open
Abstract
Aging is associated with decreased vascular compliance and diminished neurovascular- and hypercapnia-evoked cerebral blood flow (CBF) responses. However, the interplay between arterial stiffness and reduced CBF responses is poorly understood. It was hypothesized that increased cerebral arterial stiffness is associated with reduced evoked responses to both, a flashing checkerboard visual stimulation (i.e., neurovascular coupling), and hypercapnia. To test this hypothesis, 20 older (64 ± 8 year; mean ± SD) and 10 young (30 ± 5 year) subjects underwent a visual stimulation (VS) and a hypercapnic test. Blood velocity through the posterior (PCA) and middle cerebral (MCA) arteries was measured concurrently using transcranial Doppler ultrasound (TCD). Cerebral and systemic vascular stiffness were calculated from the cerebral blood velocity and systemic blood pressure waveforms, respectively. Cerebrovascular (MCA: young = 76 ± 15%, older = 98 ± 19%, p = 0.004; PCA: young = 80 ± 16%, older = 106 ± 17%, p < 0.001) and systemic (young = 59 ± 9% and older = 80 ± 9%, p < 0.001) augmentation indices (AI) were higher in the older group. CBF responses to VS (PCA: p < 0.026) and hypercapnia (PCA: p = 0.018; MCA: p = 0.042) were lower in the older group. A curvilinear model fitted to cerebral AI and age showed AI increases until ~60 years of age, after which the increase levels off (PCA: R (2) = 0.45, p < 0.001; MCA: R (2) = 0.31, p < 0.001). Finally, MCA, but not PCA, hypercapnic reactivity was inversely related to cerebral AI (MCA: R (2) = 0.28, p = 0.002; PCA: R (2) = 0.10, p = 0.104). A similar inverse relationship was not observed with the PCA blood flow response to VS (R (2) = 0.06, p = 0.174). In conclusion, older subjects had reduced neurovascular- and hypercapnia-mediated CBF responses. Furthermore, lower hypercapnia-mediated blood flow responses through the MCA were associated with increased vascular stiffness. These findings suggest the reduced hypercapnia-evoked CBF responses through the MCA, in older individuals may be secondary to vascular stiffening.
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Affiliation(s)
- Daniela Flück
- Department of Biology, Institute of Human Movement Sciences and Sport, ETH Zurich Zurich, Switzerland ; Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary Calgary, AB, Canada
| | - Andrew E Beaudin
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary Calgary, AB, Canada
| | - Craig D Steinback
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary Calgary, AB, Canada
| | - Gopukumar Kumarpillai
- Department of Clinical Neurosciences, Faculty of Medicine, University of Calgary Calgary, AB, Canada
| | - Nandavar Shobha
- Department of Clinical Neurosciences, Faculty of Medicine, University of Calgary Calgary, AB, Canada
| | - Cheryl R McCreary
- Department of Clinical Neurosciences, Faculty of Medicine, University of Calgary Calgary, AB, Canada ; Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary Calgary, AB, Canada ; Department of Radiology, Faculty of Medicine, University of Calgary Calgary, AB, Canada ; Seaman Family MR Research Centre, Foothills Medical Centre, Alberta Health Services Calgary, AB, Canada
| | - Stefano Peca
- Seaman Family MR Research Centre, Foothills Medical Centre, Alberta Health Services Calgary, AB, Canada
| | - Eric E Smith
- Department of Clinical Neurosciences, Faculty of Medicine, University of Calgary Calgary, AB, Canada ; Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary Calgary, AB, Canada ; Seaman Family MR Research Centre, Foothills Medical Centre, Alberta Health Services Calgary, AB, Canada
| | - Marc J Poulin
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary Calgary, AB, Canada ; Department of Clinical Neurosciences, Faculty of Medicine, University of Calgary Calgary, AB, Canada ; Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary Calgary, AB, Canada ; Faculty of Kinesiology, University of Calgary Calgary, AB, Canada ; The Libin Cardiovascular Institute of Alberta, Faculty of Medicine, University of Calgary Calgary, AB, Canada
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13
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Robertson JW, Debert CT, Frayne R, Poulin MJ. Variability of middle cerebral artery blood flow with hypercapnia in women. ULTRASOUND IN MEDICINE & BIOLOGY 2008; 34:730-740. [PMID: 18160203 DOI: 10.1016/j.ultrasmedbio.2007.07.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 07/03/2007] [Accepted: 07/16/2007] [Indexed: 05/25/2023]
Abstract
We examined the effect of euoxic hypercapnia on middle cerebral artery (MCA) blood flow velocity waveform parameters in pre- and postmenopausal women by exposing 24 healthy women (12 pre-, 12 postmenopausal) to hypercapnia for 20 min. MCA blood flow velocity was measured continuously by transcranial Doppler ultrasound. The data were run through an algorithm that detected the feature points of the waveforms and then analyzed for statistically significant group differences. The changes in mean blood flow velocity with euoxic hypercapnia were not significant between the two groups. However, certain feature points, particularly the velocity of the reflected shoulder (V(REFLEC)), increased (89.4 +/- 14.6 to 110.0 +/- 20.5 cm/s and 102.3 +/- 14.1 to 125.1 +/- 14.9 cm/s from euoxic eucapnia to euoxic hypercapnia in pre- and postmenopausal women, respectively), as did the augmentation index (79.9 +/- 10.4 to 85.9 +/- 12.6% and 114.7 +/- 12.8 to 119.0 +/- 12.6%) and pulsatility index (0.86 +/- 0.18 to 0.74 +/- 0.15 and 0.71 +/- 0.11 to 0.66 +/- 0.11). Furthermore, while systolic peak velocity (V(SYS)) was the highest point of the waveform in premenopausal women, V(REFLEC) was the highest point for the postmenopausal cohort. The implications of this finding become obvious when calculating pulsatility index (PI), the values of which varied significantly for the postmenopausal women, depending on whether V(SYS) or the absolute maximum was used. These findings suggest that hypercapnia increases blood flow velocity waveform reflections, and that PI calculations, particularly for older age groups, may need to be considered more carefully, since these reflections often exceed the systolic peak velocity.
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Affiliation(s)
- Jason W Robertson
- Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
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Harris AD, Ide K, Poulin MJ, Frayne R. Control of end-tidal PCO2 reduces middle cerebral artery blood velocity variability: implications for physiological neuroimaging. Neuroimage 2005; 29:1272-7. [PMID: 16226042 DOI: 10.1016/j.neuroimage.2005.08.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Revised: 08/09/2005] [Accepted: 08/23/2005] [Indexed: 11/28/2022] Open
Abstract
Breath-by-breath variability of the end-tidal partial pressure of CO2 (Pet(CO2)) has been shown to be associated with cerebral blood flow (CBF) fluctuations. These fluctuations can impact neuroimaging techniques that depend on cerebrovascular blood flow. We hypothesized that controlling Pet(CO2) would reduce CBF variability. Dynamic end-tidal forcing was used to control Pet(CO2) at 1.5 mm Hg above the resting level and to hold the end-tidal partial pressure of oxygen (Pet(O2)) at the resting level. Peak blood velocity in the middle cerebral artery (MCA) was measured by transcranial Doppler ultrasound (TCD) as an index of CBF. Blood velocity parameters and timing features were determined on each waveform and the variance of these parameters was compared between Normal (air breathing) and Forcing (end-tidal gas control) sessions. The variability of all velocity parameters was significantly reduced in the Forcing session. In particular, the variability of the average velocity over the cardiac cycle was decreased by 18.2% (P < 0.001). For the most part, the variability of the timing parameters was unchanged. Thus, we conclude that controlling Pet(CO2) is effective in reducing CBF variability, which would have important implications for physiologic neuroimaging.
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Affiliation(s)
- Ashley D Harris
- Biomedical Engineering Program, University of Calgary, Canada
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