Research Topics
| Ilias TachtsidisSummaryAffiliation: University College London Country: UK Publications
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Detail Information
Publications
Investigation of cerebral haemodynamics by near-infrared spectroscopy in young healthy volunteers reveals posture-dependent spontaneous oscillationsIlias Tachtsidis
Department of Medical Physics and Bioengineering, University College London, London WC1E 6JA, UK
Physiol Meas 25:437-45. 2004..Oscillatory changes in [O2Hb] and TOI, which may be related to the degree of cerebral sympathetic stimulation, are posture dependent in healthy subjects...
Functional optical topography analysis using statistical parametric mapping (SPM) methodology with and without physiological confoundsIlias Tachtsidis
Biomedical Optics Research Laboratory, Department of Medical Physics and Bioengineering, University College London, Gower Street, London WC1E 6BT, UK
Adv Exp Med Biol 662:237-43. 2010..Group analysis using SPM showed significant correlation in a large number of OT channels between HbO(2) and systemic regressors; however no differences in activation areas were seen between the two approaches...- Analysis of the changes in the oxidation of brain tissue cytochrome-c-oxidase in traumatic brain injury patients during hypercapnoea: a broadband NIRS studyIlias Tachtsidis
Biomedical Optics Research Laboratory, Department of Medical Physics and Bioengineering, University College London, Gower Street, London WC1E 6BT, UK
Adv Exp Med Biol 701:9-14. 2011..Further work using model informed data interpretation may be helpful in understanding the multimodal signals acquired in this heterogeneous patient group... - Measurement of frontal lobe functional activation and related systemic effects: a near-infrared spectroscopy investigationIlias Tachtsidis
Medical Physics and Bioengineering, University College London, Malet Place Engineering Building, Gower Street, London WC1E 6BT
Adv Exp Med Biol 614:397-403. 2008..The [HbO2] and [HHb] signals measured over the frontal region were found to have a varying association with the MBP signal across different volunteers. The effect of these systemic changes on measured NIRS signals must be considered.. - Measurement of cerebral tissue oxygenation in young healthy volunteers during acetazolamide provocation: a transcranial Doppler and near-infrared spectroscopy investigationIlias Tachtsidis
Medical Physics and Bioengineering, University College London, Malet Place Engineering Building, Gower Street, London WCIE 6BT
Adv Exp Med Biol 614:389-96. 2008..This work suggests that using this commercial NIRS instrument with an optode spacing of 5 cm one is able to detect the intracranial changes... - A hybrid multi-distance phase and broadband spatially resolved spectrometer and algorithm for resolving absolute concentrations of chromophores in the near-infrared light spectrumIlias Tachtsidis
Biomedical Optics Research Laboratory, Department of Medical Physics and Bioengineering, University College London, Gower Street, London WC1E 6BT, UK
Adv Exp Med Biol 662:169-75. 2010..Preliminary results in solid phantoms as well as liquid dynamic homogeneous and inhomogeneous phantoms and in-vivo muscle measurements showed encouraging results... - Investigation of in vivo measurement of cerebral cytochrome-c-oxidase redox changes using near-infrared spectroscopy in patients with orthostatic hypotensionI Tachtsidis
Department of Medical Physics and Bioengineering, Malet Place Engineering Building, University College London, Gower Street, London, UK
Physiol Meas 28:199-211. 2007..Further investigation is required to determine the clinical significance of the changes in [(ox)CCO]... - Quantification of adult cerebral blood volume using the NIRS tissue oxygenation indexIlias Tachtsidis
Medical Physics and Bioengineering, University College London, Shropshire House, 11-20 Capper Street, London
Adv Exp Med Biol 578:237-43. 2006 - Spectral characteristics of spontaneous oscillations in cerebral haemodynamics are posture dependentIlias Tachtsidis
Department of Medical Physics and Bioengineering, University College London, London WC1E 6JA, UK
Adv Exp Med Biol 540:31-6. 2003 - Normobaric hyperoxia does not change optical scattering or pathlength but does increase oxidised cytochrome C oxidase concentration in patients with brain injuryArnab Ghosh
Institute of Neurology, University College London, London, UK
Adv Exp Med Biol 765:67-72. 2013..These results suggest that the measurement of chromophore concentration in the injured brain is not confounded by changes in optical scattering or pathlength and that NBH induces an increase in cerebral aerobic metabolism... - Cerebral tissue oxygen saturation calculated using low frequency haemoglobin oscillations measured by near infrared spectroscopy in adult ventilated patientsTerence S Leung
Department of Medical Physics and Bioengineering, University College London, London, UK
Adv Exp Med Biol 614:235-44. 2008..This measure of S(osc)O2 may provide a viable, continuous, non invasive, bedside measure of cerebral venous oxygen saturation... - Investigation of oxygen saturation derived from cardiac pulsations measured on the adult head using NIR spectroscopyTerence S Leung
Department of Medical Physics and Bioengineering, University College London, London, WC1E 6JA, UK
Adv Exp Med Biol 578:209-15. 2006 
The effect on cerebral tissue oxygenation index of changes in the concentrations of inspired oxygen and end-tidal carbon dioxide in healthy adult volunteersMartin M Tisdall
Department of Neuroanaesthesia and Neurocritical Care, The National Hospital for Neurology and Neurosurgery, University College London Hospitals, London, UK
Anesth Analg 109:906-13. 2009..We designed this study to investigate the effect of systemic and intracranial physiological changes on TOI...- Measurement of the absolute optical properties and cerebral blood volume of the adult human head with hybrid differential and spatially resolved spectroscopyTerence S Leung
Department of Medical Physics and Bioengineering, University College London, Gower Street, London WC1E 6BT, UK
Phys Med Biol 51:703-17. 2006..9 +/- 10.0) x 10(-4) mm(-1) and -0.084 +/- 0.266 mm(-1), respectively. The method we describe extends the functionality of the current SRS instrumentation... - Changes in the attenuation of near infrared spectra by the healthy adult brain during hypoxaemia cannot be accounted for solely by changes in the concentrations of oxy- and deoxy-haemoglobinMartin M Tisdall
Department of Neuroanaesthesia and Neurocritical Care, The National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
Adv Exp Med Biol 614:217-25. 2008..Including [oxCCO] in the algorithm improves its fit quality. These data suggest that changes in cerebral cytochrome c oxidase redox occur during hypoxaemia and that they can be detected using NIRS... - Wavelet cross-correlation to investigate regional variations in cerebral oxygenation in infants supported on extracorporeal membrane oxygenationMaria Papademetriou
Medical Physics and Bioengineering Department, University College London, London, UK
Adv Exp Med Biol 765:203-9. 2013..Manipulations of ECMO flows are associated with regional changes in cerebral autoregulation which may potentially have an important bearing on clinical outcome... - Multichannel near infrared spectroscopy indicates regional variations in cerebral autoregulation in infants supported on extracorporeal membrane oxygenationMaria D Papademetriou
University College London, Medical Physics and Biomedical Engineering, London, United Kingdom
J Biomed Opt 17:067008. 2012.... - Estimating a modified Grubb's exponent in healthy human brains with near infrared spectroscopy and transcranial DopplerTerence S Leung
Department of Medical Physics and Bioengineering, University College London, London, UK
Physiol Meas 30:1-12. 2009..Both NIRS and transcranial Doppler techniques are non-invasive and portable, facilitating future studies in other population groups such as brain-injured patients... - Investigation of frontal cortex, motor cortex and systemic haemodynamic changes during anagram solvingIlias Tachtsidis
Department of Medical Physics and Bioengineering, Malet Place Engineering Building, Gower Street, University College London, London, UK WC1E 6BT
Adv Exp Med Biol 614:21-8. 2008..05) and flux (n = 9, p = 0.05). The task-related changes seen in MBP and flux in this study appear to contribute to the changes in the NIRS signals over both the activated and control regions of the cortex... - Theoretical investigation of measuring cerebral blood flow in the adult human head using bolus Indocyanine Green injection and near-infrared spectroscopyTerence S Leung
Department of Medical Physics, University College London, London, UK
Appl Opt 46:1604-14. 2007..The dispersion of the arterial input function also affected the CBF estimates... - Modelling cerebrovascular reactivity: a novel near-infrared biomarker of cerebral autoregulation?David Highton
University College Hospitals, Queen Square, London, UK
Adv Exp Med Biol 765:87-93. 2013..Further development of this technique could be used to track CVPR providing targets for individualised management of patients with altered vascular reactivity, minimising secondary neurological insults... - Relationship between brain tissue haemodynamics, oxygenation and metabolism in the healthy human adult brain during hyperoxia and hypercapneaIlias Tachtsidis
Department of Medical Physics and Bioengineering, Malet Place Engineering Building, University College London, Gower Street, London WC1E 6BT, UK
Adv Exp Med Biol 645:315-20. 2009..83, r=0.93 and r=0.82) but not with Vmca (r=0.33). We conclude that an increase in [oxCCO] was seen during both challenges and it was highly associated with brain tissue oxygenation... - Quantification of systemic interference in optical topography data during frontal lobe and motor cortex activation: an independent component analysisSundeep Patel
Biomedical Optics Research Laboratory, Department of Medical Physics and Bioengineering, University College London, Gower Street, London WC1E 6BT, UK
Adv Exp Med Biol 701:45-51. 2011..This analysis can therefore extract the true OT haemodynamic neuronal response and hence discriminate between regional activated cortical areas and global haemodynamic changes... - Modelling noninvasively measured cerebral signals during a hypoxemia challenge: steps towards individualised modellingBeth Jelfs
Department of Medical Physics and Bioengineering, University College London, London, United Kingdom
PLoS ONE 7:e38297. 2012..Discrepancies between model and data which persist despite model optimisation are used to flag up important questions concerning the underlying physiology, and the reliability and physiological meaning of the signals... - Systematic investigation of changes in oxidized cerebral cytochrome c oxidase concentration during frontal lobe activation in healthy adultsChristina Kolyva
Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
Biomed Opt Express 3:2550-66. 2012..We conclude that the heterogeneity in the Δ[oxCCO] response is physiological and not induced by confounding factors in the measurements... - Changes in cerebral oxygenation and haemodynamics during postural blood pressure changes in patients with autonomic failureKatharine Hunt
Department of Neuroanaesthesia and Neurocritical Care, The National Hospital for Neurology and Neurosurgery and Institute of Neurology, Queen Square, London WC1N 3BG, UK. Centre for Anaesthesia, University College London, UK
Physiol Meas 27:777-85. 2006..Postural hypotension in patients with autonomic failure is associated with a substantial decrease in absolute cerebral oxygenation measured by NIRS and this might reflect a critical reduction in cerebral oxygen delivery... - Measurement of the optical properties of the adult human head with spatially resolved spectroscopy and changes of postureTerence S Leung
Department of Medical Physics and Bioengineering, University College London, London WC1E 6JA, UK
Adv Exp Med Biol 540:13-8. 2003 - Oscillations in cerebral haemodynamics in patients with falciparum malariaChristina Kolyva
Department of Medical Physics and Bioengineering, University College London, London, UK
Adv Exp Med Biol 765:101-7. 2013..This may be related to autonomic dysfunction in severe malaria, a topic of little research to date. The present study demonstrated that application of NIRS in a resource-poor setting is feasible and has potential as a research tool... - Computational modelling of the piglet brain to simulate near-infrared spectroscopy and magnetic resonance spectroscopy data collected during oxygen deprivationTracy Moroz
CoMPLEX, University College London, London, UK
J R Soc Interface 9:1499-509. 2012..Finally, the model is used to investigate hypotheses regarding changes in CCO redox state during anoxia... - Effects of assuming constant optical scattering on haemoglobin concentration measurements using NIRS during a Valsalva manoeuvreLei Gao
Biomedical Optics Research Laboratory, Department of Medical Physics and Bioengineering, University College London, Gower Street, London WC1E 6BT, UK
Adv Exp Med Biol 701:15-20. 2011..However, these scattering changes do not appear to significantly affect the differential pathlength factor and the tissue haemoglobin concentration measurements... - False positives in functional near-infrared topographyIlias Tachtsidis
Department of Medical Physics and Bioengineering, Malet Place Engineering Building, University College London, Gower Street, London WC1E 6BT, UK
Adv Exp Med Biol 645:307-14. 2009..This lead to false positive haemodynamic maps of activation. It is therefore necessary to use statistical testing that incorporates the systemic changes that occur during brain activation... - Cerebral and peripheral tissue oxygenation in children supported on ECMO for cardio-respiratory failureMaria D Papademetriou
Biomedical Optics Research Laboratory, Department of Medical Physics and Bioengineering, University College London, Gower Street, London WC1E 6BT, UK
Adv Exp Med Biol 662:447-53. 2010..Spectral analysis was performed on the oxyhaemoglobin data collected from these patients with the aim of comparing oscillations at range of frequencies appearing in the two measurement sites... - Near-infrared spectroscopic quantification of changes in the concentration of oxidized cytochrome c oxidase in the healthy human brain during hypoxemiaMartin M Tisdall
The National Hospital for Neurology and Neurosurgery, Department of Neuroanaesthesia and Neurocritical Care, Queen Square, London WC1N 3BG, United Kingdom
J Biomed Opt 12:024002. 2007..This is the first description of cerebral Delta[oxCCO] during hypoxemia in healthy adults. Studies are ongoing to investigate the clinical relevance of this signal in patients with traumatic brain injury... - A physiological model of cerebral blood flow controlMurad Banaji
Department of Medical Physics and Bioengineering, University College London, Gower Street, London WC1E 6BT, UK
Math Biosci 194:125-73. 2005..The simulations presented are preliminary, but show qualitative agreement between model behaviour and experimental results... - Rate of change in cerebral oxygenation and blood pressure in response to passive changes in posture: a comparison between pure autonomic failure patients and controlsIlias Tachtsidis
Adv Exp Med Biol 566:187-93. 2005..05). MBP slope magnitudes showed significant differences for phases 2 (P < .01) and 5 (P < .01). These differences in the rate of change suggest differences in blood vessel resistance related to sympathetic activation... - Circulation time in man from lung to periphery as an indirect index of cardiac outputChris B Wolff
Adv Exp Med Biol 566:311-6. 2005..The relationship for normal subjects was: Ct = 0.28 x 60/Q(if) + 2.8 sec (Q(if) in L min.; P slope < .001)... - Increase in cerebral aerobic metabolism by normobaric hyperoxia after traumatic brain injuryMartin M Tisdall
Department of Neuroanaesthesia and Neurocritical Care, The National Hospital for Neurology and Neurosurgery, UK
J Neurosurg 109:424-32. 2008..They investigated the effects on cellular and mitochondrial redox states measured by the brain tissue lactate/pyruvate ratio (LPR) and the change in oxidized cytochrome c oxidase (CCO) concentration, respectively...