The Experts below are selected from a list of 36144 Experts worldwide ranked by ideXlab platform

Seonggi Kim - One of the best experts on this subject based on the ideXlab platform.

  • gradient echo and spin echo Blood Oxygenation level dependent functional mri at ultrahigh fields of 9 4 and 15 2 tesla
    Magnetic Resonance in Medicine, 2019
    Co-Authors: Sohyun Han, Jeong Pyo Son, Hyungjoon Cho, Jang-yeon Park, Seonggi Kim
    Abstract:

    Purpose Sensitivity and specificity of Blood Oxygenation level-dependent (BOLD) functional MRI (fMRI) is sensitive to magnetic field strength and acquisition methods. We have investigated gradient-echo (GE)- and spin-echo (SE)-BOLD fMRI at ultrahigh fields of 9.4 and 15.2 Tesla. Methods BOLD fMRI experiments responding to forepaw stimulation were performed with 3 echo times (TE) at each echo type and B0 in α-chloralose-anesthetized rats. The contralateral forelimb somatosensory region was selected for quantitative analyses. Results At 9.4 T and 15.2 T, average baseline T2 * (n = 9) was 26.6 and 17.1 msec, whereas baseline T2 value (n = 9) was 35.7 and 24.5 msec, respectively. Averaged stimulation-induced ΔR2 * was -1.72 s-1 at 9.4 T and -3.09 s-1 at 15.2 T, whereas ΔR2 was -1.19 s-1 at 9.4 T and -1.97 s-1 at 15.2 T. At the optimal TE of tissue T2 * or T2 , BOLD percent changes were slightly higher at 15.2 T than at 9.4 T (GE: 7.4% versus 6.4% and SE: 5.7% versus 5.4%). The ΔR2 * and ΔR2 ratio of 15.2 T to 9.4 T was 1.8 and 1.66, respectively. The ratio of the macrovessel-containing superficial to microvessel-dominant parenchymal BOLD signal was 1.73 to 1.76 for GE-BOLD versus 1.13 to 1.19 for SE-BOLD, indicating that the SE-BOLD contrast is less sensitive to macrovessels than GE-BOLD. Conclusion SE-BOLD fMRI improves spatial specificity to microvessels compared to GE-BOLD at both fields. BOLD sensitivity is similar at the both fields and can be improved at ultrahigh fields only for thermal-noise-dominant ultrahigh-resolution fMRI.

  • Gradient-echo and spin-echo Blood Oxygenation level-dependent functional MRI at ultrahigh fields of 9.4 and 15.2 Tesla: BOLD fMRI at ultrahigh fields
    WILEY-BLACKWELL, 2019
    Co-Authors: Sohyun Han, Jeong Pyo Son, Hyungjoon Cho, Jang-yeon Park, Seonggi Kim
    Abstract:

    * Purpose: Sensitivity and specificity of Blood Oxygenation level–dependent (BOLD) functional MRI (fMRI) is sensitive to magnetic field strength and acquisition methods. We have investigated gradient‐echo (GE)‐ and spin‐echo (SE)‐BOLD fMRI at ultrahigh fields of 9.4 and 15.2 Tesla (T). * Methods: BOLD fMRI experiments responding to forepaw stimulation were performed with 3 echo times (TE) at each echo type and B0© 2018 International Society for Magnetic Resonance in Medicine in α‐chloralose–anesthetized rats. The contralateral forelimb somatosensory region was selected for quantitative analyses

  • biophysical and physiological origins of Blood Oxygenation level dependent fmri signals
    Journal of Cerebral Blood Flow and Metabolism, 2012
    Co-Authors: Seonggi Kim, Seiji Ogawa
    Abstract:

    After its discovery in 1990, Blood Oxygenation level-dependent (BOLD) contrast in functional magnetic resonance imaging (fMRI) has been widely used to map brain activation in humans and animals. Since fMRI relies on signal changes induced by neural activity, its signal source can be complex and is also dependent on imaging parameters and techniques. In this review, we identify and describe the origins of BOLD fMRI signals, including the topics of (1) effects of spin density, volume fraction, inflow, perfusion, and susceptibility as potential contributors to BOLD fMRI, (2) intravascular and extravascular contributions to conventional gradient-echo and spin-echo BOLD fMRI, (3) spatial specificity of hemodynamic-based fMRI related to vascular architecture and intrinsic hemodynamic responses, (4) BOLD signal contributions from functional changes in cerebral Blood flow (CBF), cerebral Blood volume (CBV), and cerebral metabolic rate of O2 utilization (CMRO2), (5) dynamic responses of BOLD, CBF, CMRO2, and arterial and venous CBV, (6) potential sources of initial BOLD dips, poststimulus BOLD undershoots, and prolonged negative BOLD fMRI signals, (7) dependence of stimulus-evoked BOLD signals on baseline physiology, and (8) basis of resting-state BOLD fluctuations. These discussions are highly relevant to interpreting BOLD fMRI signals as physiological means.

  • neural interpretation of Blood Oxygenation level dependent fmri maps at submillimeter columnar resolution
    The Journal of Neuroscience, 2007
    Co-Authors: Chanhong Moon, Mitsuhiro Fukuda, Sunghong Park, Seonggi Kim
    Abstract:

    Whether conventional gradient-echo (GE) Blood Oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is able to map submillimeter-scale functional columns remains debatable mainly because of the spatially nonspecific large vessel contribution, poor sensitivity and reproducibility, and lack of independent evaluation. Furthermore, if the results from optical imaging of intrinsic signals are directly applicable, regions with the highest BOLD signals may indicate neurally inactive domains rather than active columns when multiple columns are activated. To examine these issues, we performed BOLD fMRI at a magnetic field of 9.4 tesla to map orientation-selective columns of isoflurane-anesthetized cats. We could not convincingly map orientation columns using conventional block-design stimulation and differential analysis method because of large fluctuations of signals. However, we successfully obtained GE BOLD iso-orientation maps with high reproducibility (r = 0.74) using temporally encoded continuous cyclic orientation stimulation with Fourier data analysis, which reduces orientation-nonselective signals such as draining artifacts and is less sensitive to signal fluctuations. We further reduced large vessel contribution using the improved spin-echo (SE) BOLD method but with overall decreased sensitivity. Both GE and SE BOLD iso-orientation maps excluding large pial vascular regions were significantly correlated to maps with a known neural interpretation, which were obtained in contrast agent-aided cerebral Blood volume fMRI and total hemoglobin-based optical imaging of intrinsic signals at a hemoglobin iso-sbestic point (570 nm). These results suggest that, unlike the expectation from deoxyhemoglobin-based optical imaging studies, the highest BOLD signals are localized to the sites of increased neural activity when column-nonselective signals are suppressed.

  • effect of basal conditions on the magnitude and dynamics of the Blood Oxygenation level dependent fmri response
    Journal of Cerebral Blood Flow and Metabolism, 2002
    Co-Authors: Eric R Cohen, Kamil Ugurbil, Seonggi Kim
    Abstract:

    The effect of the basal cerebral Blood flow (CBF) on both the magnitude and dynamics of the functional hemodynamic response in humans has not been fully investigated. Thus, the hemodynamic response to visual stimulation was measured using Blood Oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in human subjects in a 7-T magnetic field under different basal conditions: hypocapnia, normocapnia, and hypercapnia. Hypercapnia was induced by inhalation of a 5% carbon dioxide gas mixture and hypocapnia was produced by hyperventilation. As the fMRI baseline signal increased linearly with expired CO2 from hypocapnic to hypercapnic levels, the magnitude of the BOLD response to visual stimulation decreased linearly. Measures of the dynamics of the visually evoked BOLD response (onset time, full-width-at-half-maximum, and time-to-peak) increased linearly with the basal fMRI signal and the end-tidal CO2 level. The basal CBF level, modulated by the arterial partial pressure of CO2, signifi...

Rinat O. Esenaliev - One of the best experts on this subject based on the ideXlab platform.

  • optoacoustic monitoring of cerebral venous Blood Oxygenation though intact scalp in large animals
    Optics Express, 2012
    Co-Authors: Irene Y. Petrov, Inga Cicenaite, Yuriy Petrov, Donald S Prough, Donald J Deyo, Rinat O. Esenaliev
    Abstract:

    Monitoring (currently invasive) of cerebral venous Blood Oxygenation is a key to avoiding hypoxia-induced brain injury resulting in death or severe disability. Noninvasive, optoacoustic monitoring of cerebral venous Blood Oxygenation can potentially replace existing invasive methods. To the best of our knowledge, we report for the first time noninvasive monitoring of cerebral venous Blood Oxygenation through intact scalp that was validated with invasive, “gold standard” measurements. We performed an in vivo study in the sheep superior sagittal sinus (SSS), a large midline cerebral vein, using our novel, multi-wavelength optoacoustic system. The study results demonstrated that: 1) the optoacoustic signal from the sheep SSS is detectable through the thick, intact scalp and skull; 2) the SSS signal amplitude correlated well with wavelength and actual SSS Blood Oxygenation measured invasively using SSS catheterization, Blood sampling, and measurement with “gold standard” CO-Oximeter; 3) the optoacoustically predicted Oxygenation strongly correlated with that measured with the CO-Oximeter. Our results indicate that monitoring of cerebral venous Blood Oxygenation may be performed in humans noninvasively and accurately through the intact scalp using optoacoustic systems because the sheep scalp and skull thickness is comparable to that of humans whereas the sheep SSS is much smaller than that of humans.

  • optoacoustic monitoring of cerebral venous Blood Oxygenation through extracerebral Blood
    Biomedical Optics Express, 2012
    Co-Authors: Irene Y. Petrov, Inga Cicenaite, Yuriy Petrov, Donald S Prough, Donald J Deyo, Rinat O. Esenaliev
    Abstract:

    There is strong clinical evidence that controlling cerebral venous Oxygenation (oxyhemoglobin saturation) is critically important for patients with severe traumatic brain injury as well as for patients undergoing cardiac surgery. However, the only available method for cerebral venous Blood Oxygenation monitoring is invasive and requires catheterization of the internal jugular vein. We designed and built a novel optoacoustic monitor of cerebral venous Oxygenation as measured in the superior sagittal sinus (SSS), the large midline cerebral vein. To the best of our knowledge, optical monitoring of cerebral venous Blood Oxygenation through overlying extracerebral Blood is reported for the first time in this paper. The system was capable of detecting SSS signals in vivo at 700, 800, and 1064 nm through the thick (5–6 mm) sheep skull containing the circulating Blood. The high (submillimeter) in-depth resolution of the system provided identification of the SSS peaks in the optoacoustic signals. The SSS peak amplitude closely followed the actual SSS Blood Oxygenation measured invasively using catheterization, Blood sampling, and “gold standard” CO-Oximetry. Our data indicate the system may provide accurate measurement of the SSS Blood Oxygenation in patients with extracerebral Blood over the SSS.

  • noninvasive monitoring of cerebral Blood Oxygenation in ovine superior sagittal sinus with novel multi wavelength optoacoustic system
    Optics Express, 2009
    Co-Authors: Irina Y Petrova, Inga Cicenaite, Yuriy Petrov, Rinat O. Esenaliev, Donald J Deyo, Donald S Prough
    Abstract:

    Noninvasive monitoring of cerebral Blood Oxygenation with an optoacoustic technique offers advantages over current invasive and noninvasive methods. We report the results of in vivo studies in the sheep superior sagittal sinus (SSS), a large central cerebral vein. We changed Blood Oxygenation by increasing and decreasing the inspired fraction of oxygen (FiO(2)). Optoacoustic measurements from the SSS were performed at wavelengths of 700, 800, and 1064 nm using an optical parametric oscillator as a source of pulsed near-infrared light. Actual Oxygenation of SSS Blood was measured with a CO-Oximeter in Blood samples drawn from the SSS through a small craniotomy. The amplitude of the optoacoustic signal induced in the SSS Blood at lambda = 1064 nm closely followed the changes in Blood Oxygenation, at lambda = 800 nm was almost constant, and at lambda = 700 nm was changing in the opposite direction, all in accordance with the absorption spectra of oxy- and deoxyhemoglobin. The optoacoustically predicted Oxygenation correlated well with actual Blood Oxygenation in sheep SSS (R(2) = 0.965 to 0.990). The accuracy was excellent, with a mean difference of 4.8% to 9.3% and a standard deviation of 2.8% to 4.2%. To the best of our knowledge, this paper reports for the first time accurate measurements of cerebral venous Blood Oxygenation validated against the "gold standard" CO-Oximetry method.

  • in vivo monitoring of Blood Oxygenation in large veins with a triple wavelength optoacoustic system
    Optics Express, 2007
    Co-Authors: H P Brecht, Inga Cicenaite, Yuriy Petrov, Donald S Prough, Donald J Deyo, Irina Y Petrova, Igor Patrikeev, Rinat O. Esenaliev
    Abstract:

    A noninvasive optoacoustic technique could be a clinically useful alternative to existing, invasive methods for cerebral Oxygenation monitoring. Recently we proposed to use an optoacoustic technique for monitoring cerebral Blood Oxygenation by probing large cerebral and neck veins including the superior sagittal sinus and the internal jugular vein. In these studies we used a multi-wavelength optoacoustic system with a nanosecond optical parametric oscillator as a light source and a custom-made optoacoustic probe for the measurement of the optoacoustic signals in vivo from the area of the sheep neck overlying the external jugular vein, which is similar in diameter and depth to the human internal jugular vein. Optoacoustic signals induced in venous Blood were measured with high resolution despite the presence of a thick layer of tissues (up to 10 mm) between the external jugular vein and the optoacoustic probe. Three wavelengths were chosen to provide accurate and stable measurements of Blood Oxygenation: signals at 700 nm and 1064 nm demonstrated high correlation with actual Oxygenation measured invasively with CO-Oximeter (“gold standard”), while the signal at 800 nm (isosbestic point) was independent of Blood Oxygenation and was used for calibration.

  • Optoacoustic technique for noninvasive monitoring of Blood Oxygenation: a feasibility study.
    Applied optics, 2002
    Co-Authors: Rinat O. Esenaliev, Donald J Deyo, Massoud Motamedi, Irina V. Larina, Kirill V. Larin, Donald S Prough
    Abstract:

    Replacement of invasive monitoring of cerebral venous Oxygenation with noninvasive techniques offers great promise in the management of life-threatening neurologic illnesses including traumatic brain injury. We developed and built an optoacoustic system to noninvasively monitor cerebral venous Oxygenation; the system includes a nanosecond Nd:YAG laser and a specially designed optoacoustic probe. We tested the system in vitro in sheep Blood with experimentally varied Oxygenation. Our results demonstrated that (1) the amplitude and temporal profile of the optoacoustic waves increase with Blood Oxygenation in the range from 24% to 92%, (2) optoacoustic signals can be detected despite optical and acoustic attenuation by thick bone, and (3) the system is capable of real-time and continuous measurements. These results suggest that the optoacoustic technique is technically feasible for continuous, noninvasive monitoring of cerebral venous Oxygenation.

Kamil Ugurbil - One of the best experts on this subject based on the ideXlab platform.

  • spatial specificity of the functional mri Blood Oxygenation response relative to neuronal activity
    NeuroImage, 2018
    Co-Authors: Denis Chaimow, Kamil Ugurbil, Essa Yacoub, Amir Shmuel
    Abstract:

    Abstract Previous attempts at characterizing the spatial specificity of the Blood Oxygenation level dependent functional MRI (BOLD fMRI) response by estimating its point-spread function (PSF) have conventionally relied on retinotopic spatial representations of visual stimuli in area V1. Consequently, their estimates were confounded by the width and scatter of receptive fields of V1 neurons. Here, we circumvent these limits by instead using the inherent cortical spatial organization of ocular dominance columns (ODCs) to determine the PSF for both Gradient Echo (GE) and Spin Echo (SE) BOLD imaging at 7 Tesla. By applying Markov chain Monte Carlo sampling on a probabilistic generative model of imaging ODCs, we quantified the PSFs that best predict the spatial structure and magnitude of differential ODCs' responses. Prior distributions for the ODC model parameters were determined by analyzing published data of cytochrome oxidase patterns from post-mortem histology of human V1 and of neurophysiological ocular dominance indices. The average PSF full-widths at half-maximum obtained from differential ODCs’ responses following the removal of voxels influenced by contributions from macroscopic Blood vessels were 0.86 mm (SE) and 0.99 mm (GE). Our results provide a quantitative basis for the spatial specificity of BOLD fMRI at ultra-high fields, which can be used for planning and interpretation of high-resolution differential fMRI of fine-scale cortical organizations.

  • spatial specificity of the functional mri Blood Oxygenation response relative to neuronal activity
    bioRxiv, 2016
    Co-Authors: Denis Chaimow, Kamil Ugurbil, Essa Yacoub, Amir Shmuel
    Abstract:

    Previous attempts at characterizing the spatial specificity of the Blood Oxygenation level dependent functional MRI (BOLD fMRI) response by estimating its point-spread function (PSF) have conventionally relied on spatial representations of visual stimuli in area V1. Consequently, their estimates were confounded by the width and scatter of receptive fields of V1 neurons. Here, we circumvent these limits by instead using the inherent cortical spatial organization of ocular dominance columns (ODCs) to determine the PSF for both Gradient Echo (GE) and Spin Echo (SE) BOLD imaging at 7 Tesla. By applying Markov Chain Monte Carlo sampling on a probabilistic generative model of imaging ODCs, we quantified the PSFs that best predict the spatial structure and magnitude of differential responses of ODCs. Prior distributions for the ODC model parameters were determined by analyzing published data of cytochrome oxidase patterns from post-mortem histology of human V1 and of neurophysiological ocular dominance indices. The most probable PSF full-widths at half maximum were 0.82 mm (SE) and 1.02 mm (GE). Our results provide a quantitative basis for the spatial specificity of BOLD fMRI at ultra-high fields, which can be used for planning and interpretation of high-resolution differential fMRI of fine-scale cortical organizations.

  • effect of basal conditions on the magnitude and dynamics of the Blood Oxygenation level dependent fmri response
    Journal of Cerebral Blood Flow and Metabolism, 2002
    Co-Authors: Eric R Cohen, Kamil Ugurbil, Seonggi Kim
    Abstract:

    The effect of the basal cerebral Blood flow (CBF) on both the magnitude and dynamics of the functional hemodynamic response in humans has not been fully investigated. Thus, the hemodynamic response to visual stimulation was measured using Blood Oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in human subjects in a 7-T magnetic field under different basal conditions: hypocapnia, normocapnia, and hypercapnia. Hypercapnia was induced by inhalation of a 5% carbon dioxide gas mixture and hypocapnia was produced by hyperventilation. As the fMRI baseline signal increased linearly with expired CO2 from hypocapnic to hypercapnic levels, the magnitude of the BOLD response to visual stimulation decreased linearly. Measures of the dynamics of the visually evoked BOLD response (onset time, full-width-at-half-maximum, and time-to-peak) increased linearly with the basal fMRI signal and the end-tidal CO2 level. The basal CBF level, modulated by the arterial partial pressure of CO2, signifi...

  • comparison of Blood Oxygenation and cerebral Blood flow effects in fmri estimation of relative oxygen consumption change
    Magnetic Resonance in Medicine, 1997
    Co-Authors: Seonggi Kim, Kamil Ugurbil
    Abstract:

    The most widely-used functional magnetic resonance imaging (fMRI) technique is based on the Blood Oxygenation level dependent (BOLD) effect, which requires at least partial uncoupling between cerebral Blood flow (CBF) and oxygen consumption changes during increased mental activity. To compare BOLD and CBF effects during tasking, BOLD and flow-sensitive alternating inversion recovery (FAIR) images were acquired during visual stimulation with red goggles at a frequency of 8 Hz in an interleaved fashion. With the FAIR technique, absolute and relative CBF changes were determined. Relative oxygen consumption changes can be estimated using the BOLD and relative CBF changes. In gray matter areas in the visual cortex, absolute and relative CBF changes in humans during photic stimulation were 31 +/- 11 SD ml/100 g tissue/min and 43 +/- 16 SD % (n = 12), respectively, while the relative oxygen consumption change was close to zero. These findings agree extremely well with previous results using positron emission tomography. The BOLD signal change is not linearly correlated with the relative CBF increase across subjects and negatively correlates with the oxygen consumption change. Caution should be exercised when interpreting the BOLD percent change as a quantitative index of the CBF change, especially in inter-subject comparisons.

  • functional brain mapping by Blood Oxygenation level dependent contrast magnetic resonance imaging a comparison of signal characteristics with a biophysical model
    Biophysical Journal, 1993
    Co-Authors: S. Ogawa, David W Tank, Seonggi Kim, Hellmut Merkle, Ravi S Menon, Jutta M Ellermann, Kamil Ugurbil
    Abstract:

    It recently has been demonstrated that magnetic resonance imaging can be used to map changes in brain hemodynamics produced by human mental operations. One method under development relies on Blood Oxygenation level-dependent (BOLD) contrast: a change in the signal strength of brain water protons produced by the paramagnetic effects of venous Blood deoxyhemoglobin. Here we discuss the basic quantitative features of the observed BOLD-based signal changes, including the signal amplitude and its magnetic field dependence and dynamic effects such as a pronounced oscillatory pattern that is induced in the signal from primary visual cortex during photic stimulation experiments. The observed features are compared with the results of Monte Carlo simulations of water proton intravoxel phase dispersion produced by local field gradients generated by paramagnetic deoxyhemoglobin in nearby venous Blood vessels. The simulations suggest that the effect of water molecule diffusion is strong for the case of Blood capillaries, but, for larger venous Blood vessels, water diffusion is not an important determinant of deoxyhemoglobin-induced signal dephasing. We provide an expression for the apparent in-plane relaxation rate constant (R2*) in terms of the main magnetic field strength, the degree of the Oxygenation of the venous Blood, the venous Blood volume fraction in the tissue, and the size of the Blood vessel.

Amir Shmuel - One of the best experts on this subject based on the ideXlab platform.

  • spatial specificity of the functional mri Blood Oxygenation response relative to neuronal activity
    NeuroImage, 2018
    Co-Authors: Denis Chaimow, Kamil Ugurbil, Essa Yacoub, Amir Shmuel
    Abstract:

    Abstract Previous attempts at characterizing the spatial specificity of the Blood Oxygenation level dependent functional MRI (BOLD fMRI) response by estimating its point-spread function (PSF) have conventionally relied on retinotopic spatial representations of visual stimuli in area V1. Consequently, their estimates were confounded by the width and scatter of receptive fields of V1 neurons. Here, we circumvent these limits by instead using the inherent cortical spatial organization of ocular dominance columns (ODCs) to determine the PSF for both Gradient Echo (GE) and Spin Echo (SE) BOLD imaging at 7 Tesla. By applying Markov chain Monte Carlo sampling on a probabilistic generative model of imaging ODCs, we quantified the PSFs that best predict the spatial structure and magnitude of differential ODCs' responses. Prior distributions for the ODC model parameters were determined by analyzing published data of cytochrome oxidase patterns from post-mortem histology of human V1 and of neurophysiological ocular dominance indices. The average PSF full-widths at half-maximum obtained from differential ODCs’ responses following the removal of voxels influenced by contributions from macroscopic Blood vessels were 0.86 mm (SE) and 0.99 mm (GE). Our results provide a quantitative basis for the spatial specificity of BOLD fMRI at ultra-high fields, which can be used for planning and interpretation of high-resolution differential fMRI of fine-scale cortical organizations.

  • spatial specificity of the functional mri Blood Oxygenation response relative to neuronal activity
    bioRxiv, 2016
    Co-Authors: Denis Chaimow, Kamil Ugurbil, Essa Yacoub, Amir Shmuel
    Abstract:

    Previous attempts at characterizing the spatial specificity of the Blood Oxygenation level dependent functional MRI (BOLD fMRI) response by estimating its point-spread function (PSF) have conventionally relied on spatial representations of visual stimuli in area V1. Consequently, their estimates were confounded by the width and scatter of receptive fields of V1 neurons. Here, we circumvent these limits by instead using the inherent cortical spatial organization of ocular dominance columns (ODCs) to determine the PSF for both Gradient Echo (GE) and Spin Echo (SE) BOLD imaging at 7 Tesla. By applying Markov Chain Monte Carlo sampling on a probabilistic generative model of imaging ODCs, we quantified the PSFs that best predict the spatial structure and magnitude of differential responses of ODCs. Prior distributions for the ODC model parameters were determined by analyzing published data of cytochrome oxidase patterns from post-mortem histology of human V1 and of neurophysiological ocular dominance indices. The most probable PSF full-widths at half maximum were 0.82 mm (SE) and 1.02 mm (GE). Our results provide a quantitative basis for the spatial specificity of BOLD fMRI at ultra-high fields, which can be used for planning and interpretation of high-resolution differential fMRI of fine-scale cortical organizations.

Donald S Prough - One of the best experts on this subject based on the ideXlab platform.

  • optoacoustic monitoring of cerebral venous Blood Oxygenation though intact scalp in large animals
    Optics Express, 2012
    Co-Authors: Irene Y. Petrov, Inga Cicenaite, Yuriy Petrov, Donald S Prough, Donald J Deyo, Rinat O. Esenaliev
    Abstract:

    Monitoring (currently invasive) of cerebral venous Blood Oxygenation is a key to avoiding hypoxia-induced brain injury resulting in death or severe disability. Noninvasive, optoacoustic monitoring of cerebral venous Blood Oxygenation can potentially replace existing invasive methods. To the best of our knowledge, we report for the first time noninvasive monitoring of cerebral venous Blood Oxygenation through intact scalp that was validated with invasive, “gold standard” measurements. We performed an in vivo study in the sheep superior sagittal sinus (SSS), a large midline cerebral vein, using our novel, multi-wavelength optoacoustic system. The study results demonstrated that: 1) the optoacoustic signal from the sheep SSS is detectable through the thick, intact scalp and skull; 2) the SSS signal amplitude correlated well with wavelength and actual SSS Blood Oxygenation measured invasively using SSS catheterization, Blood sampling, and measurement with “gold standard” CO-Oximeter; 3) the optoacoustically predicted Oxygenation strongly correlated with that measured with the CO-Oximeter. Our results indicate that monitoring of cerebral venous Blood Oxygenation may be performed in humans noninvasively and accurately through the intact scalp using optoacoustic systems because the sheep scalp and skull thickness is comparable to that of humans whereas the sheep SSS is much smaller than that of humans.

  • optoacoustic monitoring of cerebral venous Blood Oxygenation through extracerebral Blood
    Biomedical Optics Express, 2012
    Co-Authors: Irene Y. Petrov, Inga Cicenaite, Yuriy Petrov, Donald S Prough, Donald J Deyo, Rinat O. Esenaliev
    Abstract:

    There is strong clinical evidence that controlling cerebral venous Oxygenation (oxyhemoglobin saturation) is critically important for patients with severe traumatic brain injury as well as for patients undergoing cardiac surgery. However, the only available method for cerebral venous Blood Oxygenation monitoring is invasive and requires catheterization of the internal jugular vein. We designed and built a novel optoacoustic monitor of cerebral venous Oxygenation as measured in the superior sagittal sinus (SSS), the large midline cerebral vein. To the best of our knowledge, optical monitoring of cerebral venous Blood Oxygenation through overlying extracerebral Blood is reported for the first time in this paper. The system was capable of detecting SSS signals in vivo at 700, 800, and 1064 nm through the thick (5–6 mm) sheep skull containing the circulating Blood. The high (submillimeter) in-depth resolution of the system provided identification of the SSS peaks in the optoacoustic signals. The SSS peak amplitude closely followed the actual SSS Blood Oxygenation measured invasively using catheterization, Blood sampling, and “gold standard” CO-Oximetry. Our data indicate the system may provide accurate measurement of the SSS Blood Oxygenation in patients with extracerebral Blood over the SSS.

  • noninvasive monitoring of cerebral Blood Oxygenation in ovine superior sagittal sinus with novel multi wavelength optoacoustic system
    Optics Express, 2009
    Co-Authors: Irina Y Petrova, Inga Cicenaite, Yuriy Petrov, Rinat O. Esenaliev, Donald J Deyo, Donald S Prough
    Abstract:

    Noninvasive monitoring of cerebral Blood Oxygenation with an optoacoustic technique offers advantages over current invasive and noninvasive methods. We report the results of in vivo studies in the sheep superior sagittal sinus (SSS), a large central cerebral vein. We changed Blood Oxygenation by increasing and decreasing the inspired fraction of oxygen (FiO(2)). Optoacoustic measurements from the SSS were performed at wavelengths of 700, 800, and 1064 nm using an optical parametric oscillator as a source of pulsed near-infrared light. Actual Oxygenation of SSS Blood was measured with a CO-Oximeter in Blood samples drawn from the SSS through a small craniotomy. The amplitude of the optoacoustic signal induced in the SSS Blood at lambda = 1064 nm closely followed the changes in Blood Oxygenation, at lambda = 800 nm was almost constant, and at lambda = 700 nm was changing in the opposite direction, all in accordance with the absorption spectra of oxy- and deoxyhemoglobin. The optoacoustically predicted Oxygenation correlated well with actual Blood Oxygenation in sheep SSS (R(2) = 0.965 to 0.990). The accuracy was excellent, with a mean difference of 4.8% to 9.3% and a standard deviation of 2.8% to 4.2%. To the best of our knowledge, this paper reports for the first time accurate measurements of cerebral venous Blood Oxygenation validated against the "gold standard" CO-Oximetry method.

  • in vivo monitoring of Blood Oxygenation in large veins with a triple wavelength optoacoustic system
    Optics Express, 2007
    Co-Authors: H P Brecht, Inga Cicenaite, Yuriy Petrov, Donald S Prough, Donald J Deyo, Irina Y Petrova, Igor Patrikeev, Rinat O. Esenaliev
    Abstract:

    A noninvasive optoacoustic technique could be a clinically useful alternative to existing, invasive methods for cerebral Oxygenation monitoring. Recently we proposed to use an optoacoustic technique for monitoring cerebral Blood Oxygenation by probing large cerebral and neck veins including the superior sagittal sinus and the internal jugular vein. In these studies we used a multi-wavelength optoacoustic system with a nanosecond optical parametric oscillator as a light source and a custom-made optoacoustic probe for the measurement of the optoacoustic signals in vivo from the area of the sheep neck overlying the external jugular vein, which is similar in diameter and depth to the human internal jugular vein. Optoacoustic signals induced in venous Blood were measured with high resolution despite the presence of a thick layer of tissues (up to 10 mm) between the external jugular vein and the optoacoustic probe. Three wavelengths were chosen to provide accurate and stable measurements of Blood Oxygenation: signals at 700 nm and 1064 nm demonstrated high correlation with actual Oxygenation measured invasively with CO-Oximeter (“gold standard”), while the signal at 800 nm (isosbestic point) was independent of Blood Oxygenation and was used for calibration.

  • Optoacoustic technique for noninvasive monitoring of Blood Oxygenation: a feasibility study.
    Applied optics, 2002
    Co-Authors: Rinat O. Esenaliev, Donald J Deyo, Massoud Motamedi, Irina V. Larina, Kirill V. Larin, Donald S Prough
    Abstract:

    Replacement of invasive monitoring of cerebral venous Oxygenation with noninvasive techniques offers great promise in the management of life-threatening neurologic illnesses including traumatic brain injury. We developed and built an optoacoustic system to noninvasively monitor cerebral venous Oxygenation; the system includes a nanosecond Nd:YAG laser and a specially designed optoacoustic probe. We tested the system in vitro in sheep Blood with experimentally varied Oxygenation. Our results demonstrated that (1) the amplitude and temporal profile of the optoacoustic waves increase with Blood Oxygenation in the range from 24% to 92%, (2) optoacoustic signals can be detected despite optical and acoustic attenuation by thick bone, and (3) the system is capable of real-time and continuous measurements. These results suggest that the optoacoustic technique is technically feasible for continuous, noninvasive monitoring of cerebral venous Oxygenation.