The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform

A Benzer - One of the best experts on this subject based on the ideXlab platform.

  • increasing Mean Airway Pressure reduces functional mri fmri signal in the primary visual cortex
    Magnetic Resonance Imaging, 2001
    Co-Authors: Ingo H Lorenz, Christian Kolbitsch, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, S Felber, A Benzer
    Abstract:

    Abstract Changes in both blood flow and blood oxygenation determine the functional MRI (fMRI) signal. In the present study factors responsible for blood oxygenation (e.g., FiO 2 ) were held constant so that changes in pixel count would above all reflect changes in regional cerebral blood flow (rCBF). Continuous positive Airway Pressure (CPAP) breathing at 12 cm H 2 O, which was previously shown to influence rCBF, was applied in human volunteers ( n = 19) to investigate the sensitivity of fMRI for changes in rCBF caused by increased Mean Airway Pressure. Increasing the Mean Airway Pressure decreased the pixel count in the primary visual cortex (median (range)): baseline: 219 (58–425) pixels vs. CPAP (12 cm H 2 O): 92 (0–262) pixels). These findings indicate that fMRI is sensitive to detect a reduced rCBF-response in the primary visual cortex. The underlying mechanism is likely to be a reduced basal rCBF due to constriction and/or compression of postcapillary venoles during CPAP breathing. These findings are important for interpreting fMRI results in awake and in artificially respirated patients, in whom positive Airway Pressure is used to improve pulmonary function during the diagnostic procedure.

  • the impact of increased Mean Airway Pressure on contrast enhanced mri measurement of regional cerebral blood flow rcbf regional cerebral blood volume rcbv regional Mean transit time rmtt and regional cerebrovascular resistance rcvr in human volunteer
    Human Brain Mapping, 2000
    Co-Authors: Christian Kolbitsch, Ingo H Lorenz, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, S Felber, A Benzer
    Abstract:

    Contrast-enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased Mean Airway Pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive Airway Pressure (CPAP) (12 cm H2O) to study the effects of increased Mean Airway Pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional Mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when Mean Airway Pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast-enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive Airway Pressure.

Christian Kolbitsch - One of the best experts on this subject based on the ideXlab platform.

  • increasing Mean Airway Pressure reduces functional mri fmri signal in the primary visual cortex
    Magnetic Resonance Imaging, 2001
    Co-Authors: Ingo H Lorenz, Christian Kolbitsch, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, S Felber, A Benzer
    Abstract:

    Abstract Changes in both blood flow and blood oxygenation determine the functional MRI (fMRI) signal. In the present study factors responsible for blood oxygenation (e.g., FiO 2 ) were held constant so that changes in pixel count would above all reflect changes in regional cerebral blood flow (rCBF). Continuous positive Airway Pressure (CPAP) breathing at 12 cm H 2 O, which was previously shown to influence rCBF, was applied in human volunteers ( n = 19) to investigate the sensitivity of fMRI for changes in rCBF caused by increased Mean Airway Pressure. Increasing the Mean Airway Pressure decreased the pixel count in the primary visual cortex (median (range)): baseline: 219 (58–425) pixels vs. CPAP (12 cm H 2 O): 92 (0–262) pixels). These findings indicate that fMRI is sensitive to detect a reduced rCBF-response in the primary visual cortex. The underlying mechanism is likely to be a reduced basal rCBF due to constriction and/or compression of postcapillary venoles during CPAP breathing. These findings are important for interpreting fMRI results in awake and in artificially respirated patients, in whom positive Airway Pressure is used to improve pulmonary function during the diagnostic procedure.

  • the impact of increased Mean Airway Pressure on contrast enhanced mri measurement of regional cerebral blood flow rcbf regional cerebral blood volume rcbv regional Mean transit time rmtt and regional cerebrovascular resistance rcvr in human volunteer
    Human Brain Mapping, 2000
    Co-Authors: Christian Kolbitsch, Ingo H Lorenz, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, S Felber, A Benzer
    Abstract:

    Contrast-enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased Mean Airway Pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive Airway Pressure (CPAP) (12 cm H2O) to study the effects of increased Mean Airway Pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional Mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when Mean Airway Pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast-enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive Airway Pressure.

  • The impact of increased Mean Airway Pressure on contrast-enhanced MRI measurement of regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), regional Mean transit time (rMTT), and regional cerebrovascular resistance (rCVR) in huma
    Human Brain Mapping, 2000
    Co-Authors: Christian Kolbitsch, Ingo H Lorenz, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, Stephan Felber, Arnulf Benzer
    Abstract:

    Contrast-enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased Mean Airway Pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive Airway Pressure (CPAP) (12 cm H2O) to study the effects of increased Mean Airway Pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional Mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when Mean Airway Pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast-enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive Airway Pressure. Hum. Brain Mapping 11:214–222, 2000. © 2000 Wiley-Liss, Inc.

Ingo H Lorenz - One of the best experts on this subject based on the ideXlab platform.

  • increasing Mean Airway Pressure reduces functional mri fmri signal in the primary visual cortex
    Magnetic Resonance Imaging, 2001
    Co-Authors: Ingo H Lorenz, Christian Kolbitsch, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, S Felber, A Benzer
    Abstract:

    Abstract Changes in both blood flow and blood oxygenation determine the functional MRI (fMRI) signal. In the present study factors responsible for blood oxygenation (e.g., FiO 2 ) were held constant so that changes in pixel count would above all reflect changes in regional cerebral blood flow (rCBF). Continuous positive Airway Pressure (CPAP) breathing at 12 cm H 2 O, which was previously shown to influence rCBF, was applied in human volunteers ( n = 19) to investigate the sensitivity of fMRI for changes in rCBF caused by increased Mean Airway Pressure. Increasing the Mean Airway Pressure decreased the pixel count in the primary visual cortex (median (range)): baseline: 219 (58–425) pixels vs. CPAP (12 cm H 2 O): 92 (0–262) pixels). These findings indicate that fMRI is sensitive to detect a reduced rCBF-response in the primary visual cortex. The underlying mechanism is likely to be a reduced basal rCBF due to constriction and/or compression of postcapillary venoles during CPAP breathing. These findings are important for interpreting fMRI results in awake and in artificially respirated patients, in whom positive Airway Pressure is used to improve pulmonary function during the diagnostic procedure.

  • the impact of increased Mean Airway Pressure on contrast enhanced mri measurement of regional cerebral blood flow rcbf regional cerebral blood volume rcbv regional Mean transit time rmtt and regional cerebrovascular resistance rcvr in human volunteer
    Human Brain Mapping, 2000
    Co-Authors: Christian Kolbitsch, Ingo H Lorenz, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, S Felber, A Benzer
    Abstract:

    Contrast-enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased Mean Airway Pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive Airway Pressure (CPAP) (12 cm H2O) to study the effects of increased Mean Airway Pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional Mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when Mean Airway Pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast-enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive Airway Pressure.

  • The impact of increased Mean Airway Pressure on contrast-enhanced MRI measurement of regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), regional Mean transit time (rMTT), and regional cerebrovascular resistance (rCVR) in huma
    Human Brain Mapping, 2000
    Co-Authors: Christian Kolbitsch, Ingo H Lorenz, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, Stephan Felber, Arnulf Benzer
    Abstract:

    Contrast-enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased Mean Airway Pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive Airway Pressure (CPAP) (12 cm H2O) to study the effects of increased Mean Airway Pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional Mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when Mean Airway Pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast-enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive Airway Pressure. Hum. Brain Mapping 11:214–222, 2000. © 2000 Wiley-Liss, Inc.

Fritz Zschiegner - One of the best experts on this subject based on the ideXlab platform.

  • increasing Mean Airway Pressure reduces functional mri fmri signal in the primary visual cortex
    Magnetic Resonance Imaging, 2001
    Co-Authors: Ingo H Lorenz, Christian Kolbitsch, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, S Felber, A Benzer
    Abstract:

    Abstract Changes in both blood flow and blood oxygenation determine the functional MRI (fMRI) signal. In the present study factors responsible for blood oxygenation (e.g., FiO 2 ) were held constant so that changes in pixel count would above all reflect changes in regional cerebral blood flow (rCBF). Continuous positive Airway Pressure (CPAP) breathing at 12 cm H 2 O, which was previously shown to influence rCBF, was applied in human volunteers ( n = 19) to investigate the sensitivity of fMRI for changes in rCBF caused by increased Mean Airway Pressure. Increasing the Mean Airway Pressure decreased the pixel count in the primary visual cortex (median (range)): baseline: 219 (58–425) pixels vs. CPAP (12 cm H 2 O): 92 (0–262) pixels). These findings indicate that fMRI is sensitive to detect a reduced rCBF-response in the primary visual cortex. The underlying mechanism is likely to be a reduced basal rCBF due to constriction and/or compression of postcapillary venoles during CPAP breathing. These findings are important for interpreting fMRI results in awake and in artificially respirated patients, in whom positive Airway Pressure is used to improve pulmonary function during the diagnostic procedure.

  • the impact of increased Mean Airway Pressure on contrast enhanced mri measurement of regional cerebral blood flow rcbf regional cerebral blood volume rcbv regional Mean transit time rmtt and regional cerebrovascular resistance rcvr in human volunteer
    Human Brain Mapping, 2000
    Co-Authors: Christian Kolbitsch, Ingo H Lorenz, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, S Felber, A Benzer
    Abstract:

    Contrast-enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased Mean Airway Pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive Airway Pressure (CPAP) (12 cm H2O) to study the effects of increased Mean Airway Pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional Mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when Mean Airway Pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast-enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive Airway Pressure.

  • The impact of increased Mean Airway Pressure on contrast-enhanced MRI measurement of regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), regional Mean transit time (rMTT), and regional cerebrovascular resistance (rCVR) in huma
    Human Brain Mapping, 2000
    Co-Authors: Christian Kolbitsch, Ingo H Lorenz, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, Stephan Felber, Arnulf Benzer
    Abstract:

    Contrast-enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased Mean Airway Pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive Airway Pressure (CPAP) (12 cm H2O) to study the effects of increased Mean Airway Pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional Mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when Mean Airway Pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast-enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive Airway Pressure. Hum. Brain Mapping 11:214–222, 2000. © 2000 Wiley-Liss, Inc.

Christoph Hormann - One of the best experts on this subject based on the ideXlab platform.

  • increasing Mean Airway Pressure reduces functional mri fmri signal in the primary visual cortex
    Magnetic Resonance Imaging, 2001
    Co-Authors: Ingo H Lorenz, Christian Kolbitsch, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, S Felber, A Benzer
    Abstract:

    Abstract Changes in both blood flow and blood oxygenation determine the functional MRI (fMRI) signal. In the present study factors responsible for blood oxygenation (e.g., FiO 2 ) were held constant so that changes in pixel count would above all reflect changes in regional cerebral blood flow (rCBF). Continuous positive Airway Pressure (CPAP) breathing at 12 cm H 2 O, which was previously shown to influence rCBF, was applied in human volunteers ( n = 19) to investigate the sensitivity of fMRI for changes in rCBF caused by increased Mean Airway Pressure. Increasing the Mean Airway Pressure decreased the pixel count in the primary visual cortex (median (range)): baseline: 219 (58–425) pixels vs. CPAP (12 cm H 2 O): 92 (0–262) pixels). These findings indicate that fMRI is sensitive to detect a reduced rCBF-response in the primary visual cortex. The underlying mechanism is likely to be a reduced basal rCBF due to constriction and/or compression of postcapillary venoles during CPAP breathing. These findings are important for interpreting fMRI results in awake and in artificially respirated patients, in whom positive Airway Pressure is used to improve pulmonary function during the diagnostic procedure.

  • the impact of increased Mean Airway Pressure on contrast enhanced mri measurement of regional cerebral blood flow rcbf regional cerebral blood volume rcbv regional Mean transit time rmtt and regional cerebrovascular resistance rcvr in human volunteer
    Human Brain Mapping, 2000
    Co-Authors: Christian Kolbitsch, Ingo H Lorenz, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, S Felber, A Benzer
    Abstract:

    Contrast-enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased Mean Airway Pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive Airway Pressure (CPAP) (12 cm H2O) to study the effects of increased Mean Airway Pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional Mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when Mean Airway Pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast-enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive Airway Pressure.

  • The impact of increased Mean Airway Pressure on contrast-enhanced MRI measurement of regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), regional Mean transit time (rMTT), and regional cerebrovascular resistance (rCVR) in huma
    Human Brain Mapping, 2000
    Co-Authors: Christian Kolbitsch, Ingo H Lorenz, Christoph Hormann, Michael Schocke, Christian Kremser, Fritz Zschiegner, Stephan Felber, Arnulf Benzer
    Abstract:

    Contrast-enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased Mean Airway Pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive Airway Pressure (CPAP) (12 cm H2O) to study the effects of increased Mean Airway Pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional Mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when Mean Airway Pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast-enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive Airway Pressure. Hum. Brain Mapping 11:214–222, 2000. © 2000 Wiley-Liss, Inc.