The Experts below are selected from a list of 28236 Experts worldwide ranked by ideXlab platform

Walter M Stadler - One of the best experts on this subject based on the ideXlab platform.

  • estimating the arterial input function using two reference tissues in dynamic contrast enhanced mri studies fundamental concepts and simulations
    Magnetic Resonance in Medicine, 2004
    Co-Authors: Cheng Yang, Gregory S Karczmar, Milica Medved, Walter M Stadler
    Abstract:

    In dynamic contrast-enhanced MRI (DCE-MRI) studies, an accurate knowledge of the arterial contrast agent Concentration as a function of time is crucial for the estimation of kinetic parameters. In this work, a novel method for estimating the arterial input function (AIF) based on the contrast agent Concentration-vs.-time curves in two different reference tissues is described. It is assumed that the AIFs of the two tissues have the same shape, and that simple models with two or more compartments, and unknown kinetic parameters, can describe their Tracer Concentration-vs.-time curves. Based on the principle of self-consistency, one can relate the two Tracer Concentration-vs.-time curves to estimate their common underlining AIF, together with the kinetic parameters of the two tissues. In practice, the measured Concentration-vs.-time curves have noise, and the AIFs of the two tissues are not exactly the same due to different dispersion effects. These factors will produce errors in the AIF estimate. Simulation studies show that despite the two error sources, the double-reference-tissue method provides reliable estimates of the AIF.

  • estimating the arterial input function using two reference tissues in dynamic contrast enhanced mri studies fundamental concepts and simulations
    Magnetic Resonance in Medicine, 2004
    Co-Authors: Cheng Yang, Gregory S Karczmar, Milica Medved, Walter M Stadler
    Abstract:

    In dynamic contrast-enhanced MRI (DCE-MRI) studies, an accurate knowledge of the arterial contrast agent Concentration as a function of time is crucial for the estimation of kinetic parameters. In this work, a novel method for estimating the arterial input function (AIF) based on the contrast agent Concentration-vs.-time curves in two different reference tissues is described. It is assumed that the AIFs of the two tissues have the same shape, and that simple models with two or more compartments, and unknown kinetic parameters, can describe their Tracer Concentration-vs.-time curves. Based on the principle of self-consistency, one can relate the two Tracer Concentration-vs.-time curves to estimate their common underlining AIF, together with the kinetic parameters of the two tissues. In practice, the measured Concentration-vs.-time curves have noise, and the AIFs of the two tissues are not exactly the same due to different dispersion effects. These factors will produce errors in the AIF estimate. Simulation studies show that despite the two error sources, the double-reference-tissue method provides reliable estimates of the AIF. Magn Reson Med 52:1110–1117, 2004. © 2004 Wiley-Liss, Inc.

James J Frost - One of the best experts on this subject based on the ideXlab platform.

  • measurement of radioTracer Concentration in brain gray matter using positron emission tomography mri based correction for partial volume effects
    Journal of Cerebral Blood Flow and Metabolism, 1992
    Co-Authors: Hans W Mullergartner, Jonathan M Links, Jerry L Prince, Nick R Bryan, Elliot R Mcveigh, Jeffrey Leal, Christos Davatzikos, James J Frost
    Abstract:

    Accuracy in in vivo quantitation of brain function with positron emission tomography (PET) has often been limited by partial volume effects. This limitation becomes prominent in studies of aging and degenerative brain diseases where partial volume effects vary with different degrees of atrophy. The present study describes how the actual gray matter (GM) Tracer Concentration can be estimated using an algorithm that relates the regional fraction of GM to partial volume effects. The regional fraction of GM was determined by magnetic resonance imaging (MRI). The procedure is designated as GM PET. In computer simulations and phantom studies, the GM PET algorithm permitted a 100% recovery of the actual Tracer Concentration in neocortical GM and hippocampus, irrespective of the GM volume. GM PET was applied in a test case of temporal lobe epilepsy revealing an increase in radioTracer activity in GM that was undetected in the PET image before correction for partial volume effects. In computer simulations, errors ...

  • measurement of radioTracer Concentration in brain gray matter using positron emission tomography mri based correction for partial volume effects
    Journal of Cerebral Blood Flow and Metabolism, 1992
    Co-Authors: Hans W Mullergartner, Jonathan M Links, Jerry L Prince, Nick R Bryan, Elliot R Mcveigh, Christos Davatzikos, Jeffrey P Leal, James J Frost
    Abstract:

    Accuracy in in vivo quantitation of brain function with positron emission tomography (PET) has often been limited by partial volume effects. This limitation becomes prominent in studies of aging and degenerative brain diseases where partial volume effects vary with different degrees of atrophy. The present study describes how the actual gray matter (GM) Tracer Concentration can be estimated using an algorithm that relates the regional fraction of GM to partial volume effects. The regional fraction of GM was determined by magnetic resonance imaging (MRI). The procedure is designated as GM PET. In computer simulations and phantom studies, the GM PET algorithm permitted a 100% recovery of the actual Tracer Concentration in neocortical GM and hippocampus, irrespective of the GM volume. GM PET was applied in a test case of temporal lobe epilepsy revealing an increase in radioTracer activity in GM that was undetected in the PET image before correction for partial volume effects. In computer simulations, errors in the segmentation of GM and errors in registration of PET and MRI images resulted in less than 15% inaccuracy in the GM PET image. In conclusion, GM PET permits accurate determination of the actual radioTracer Concentration in human brain GM in vivo. The method differentiates whether a change in the apparent radioTracer Concentration reflects solely an alteration in GM volume or rather a change in radioTracer Concentration per unit volume of GM.

Cheng Yang - One of the best experts on this subject based on the ideXlab platform.

  • estimating the arterial input function using two reference tissues in dynamic contrast enhanced mri studies fundamental concepts and simulations
    Magnetic Resonance in Medicine, 2004
    Co-Authors: Cheng Yang, Gregory S Karczmar, Milica Medved, Walter M Stadler
    Abstract:

    In dynamic contrast-enhanced MRI (DCE-MRI) studies, an accurate knowledge of the arterial contrast agent Concentration as a function of time is crucial for the estimation of kinetic parameters. In this work, a novel method for estimating the arterial input function (AIF) based on the contrast agent Concentration-vs.-time curves in two different reference tissues is described. It is assumed that the AIFs of the two tissues have the same shape, and that simple models with two or more compartments, and unknown kinetic parameters, can describe their Tracer Concentration-vs.-time curves. Based on the principle of self-consistency, one can relate the two Tracer Concentration-vs.-time curves to estimate their common underlining AIF, together with the kinetic parameters of the two tissues. In practice, the measured Concentration-vs.-time curves have noise, and the AIFs of the two tissues are not exactly the same due to different dispersion effects. These factors will produce errors in the AIF estimate. Simulation studies show that despite the two error sources, the double-reference-tissue method provides reliable estimates of the AIF.

  • estimating the arterial input function using two reference tissues in dynamic contrast enhanced mri studies fundamental concepts and simulations
    Magnetic Resonance in Medicine, 2004
    Co-Authors: Cheng Yang, Gregory S Karczmar, Milica Medved, Walter M Stadler
    Abstract:

    In dynamic contrast-enhanced MRI (DCE-MRI) studies, an accurate knowledge of the arterial contrast agent Concentration as a function of time is crucial for the estimation of kinetic parameters. In this work, a novel method for estimating the arterial input function (AIF) based on the contrast agent Concentration-vs.-time curves in two different reference tissues is described. It is assumed that the AIFs of the two tissues have the same shape, and that simple models with two or more compartments, and unknown kinetic parameters, can describe their Tracer Concentration-vs.-time curves. Based on the principle of self-consistency, one can relate the two Tracer Concentration-vs.-time curves to estimate their common underlining AIF, together with the kinetic parameters of the two tissues. In practice, the measured Concentration-vs.-time curves have noise, and the AIFs of the two tissues are not exactly the same due to different dispersion effects. These factors will produce errors in the AIF estimate. Simulation studies show that despite the two error sources, the double-reference-tissue method provides reliable estimates of the AIF. Magn Reson Med 52:1110–1117, 2004. © 2004 Wiley-Liss, Inc.

Hans W Mullergartner - One of the best experts on this subject based on the ideXlab platform.

  • measurement of radioTracer Concentration in brain gray matter using positron emission tomography mri based correction for partial volume effects
    Journal of Cerebral Blood Flow and Metabolism, 1992
    Co-Authors: Hans W Mullergartner, Jonathan M Links, Jerry L Prince, Nick R Bryan, Elliot R Mcveigh, Jeffrey Leal, Christos Davatzikos, James J Frost
    Abstract:

    Accuracy in in vivo quantitation of brain function with positron emission tomography (PET) has often been limited by partial volume effects. This limitation becomes prominent in studies of aging and degenerative brain diseases where partial volume effects vary with different degrees of atrophy. The present study describes how the actual gray matter (GM) Tracer Concentration can be estimated using an algorithm that relates the regional fraction of GM to partial volume effects. The regional fraction of GM was determined by magnetic resonance imaging (MRI). The procedure is designated as GM PET. In computer simulations and phantom studies, the GM PET algorithm permitted a 100% recovery of the actual Tracer Concentration in neocortical GM and hippocampus, irrespective of the GM volume. GM PET was applied in a test case of temporal lobe epilepsy revealing an increase in radioTracer activity in GM that was undetected in the PET image before correction for partial volume effects. In computer simulations, errors ...

  • measurement of radioTracer Concentration in brain gray matter using positron emission tomography mri based correction for partial volume effects
    Journal of Cerebral Blood Flow and Metabolism, 1992
    Co-Authors: Hans W Mullergartner, Jonathan M Links, Jerry L Prince, Nick R Bryan, Elliot R Mcveigh, Christos Davatzikos, Jeffrey P Leal, James J Frost
    Abstract:

    Accuracy in in vivo quantitation of brain function with positron emission tomography (PET) has often been limited by partial volume effects. This limitation becomes prominent in studies of aging and degenerative brain diseases where partial volume effects vary with different degrees of atrophy. The present study describes how the actual gray matter (GM) Tracer Concentration can be estimated using an algorithm that relates the regional fraction of GM to partial volume effects. The regional fraction of GM was determined by magnetic resonance imaging (MRI). The procedure is designated as GM PET. In computer simulations and phantom studies, the GM PET algorithm permitted a 100% recovery of the actual Tracer Concentration in neocortical GM and hippocampus, irrespective of the GM volume. GM PET was applied in a test case of temporal lobe epilepsy revealing an increase in radioTracer activity in GM that was undetected in the PET image before correction for partial volume effects. In computer simulations, errors in the segmentation of GM and errors in registration of PET and MRI images resulted in less than 15% inaccuracy in the GM PET image. In conclusion, GM PET permits accurate determination of the actual radioTracer Concentration in human brain GM in vivo. The method differentiates whether a change in the apparent radioTracer Concentration reflects solely an alteration in GM volume or rather a change in radioTracer Concentration per unit volume of GM.

Gregory S Karczmar - One of the best experts on this subject based on the ideXlab platform.

  • estimating the arterial input function using two reference tissues in dynamic contrast enhanced mri studies fundamental concepts and simulations
    Magnetic Resonance in Medicine, 2004
    Co-Authors: Cheng Yang, Gregory S Karczmar, Milica Medved, Walter M Stadler
    Abstract:

    In dynamic contrast-enhanced MRI (DCE-MRI) studies, an accurate knowledge of the arterial contrast agent Concentration as a function of time is crucial for the estimation of kinetic parameters. In this work, a novel method for estimating the arterial input function (AIF) based on the contrast agent Concentration-vs.-time curves in two different reference tissues is described. It is assumed that the AIFs of the two tissues have the same shape, and that simple models with two or more compartments, and unknown kinetic parameters, can describe their Tracer Concentration-vs.-time curves. Based on the principle of self-consistency, one can relate the two Tracer Concentration-vs.-time curves to estimate their common underlining AIF, together with the kinetic parameters of the two tissues. In practice, the measured Concentration-vs.-time curves have noise, and the AIFs of the two tissues are not exactly the same due to different dispersion effects. These factors will produce errors in the AIF estimate. Simulation studies show that despite the two error sources, the double-reference-tissue method provides reliable estimates of the AIF.

  • estimating the arterial input function using two reference tissues in dynamic contrast enhanced mri studies fundamental concepts and simulations
    Magnetic Resonance in Medicine, 2004
    Co-Authors: Cheng Yang, Gregory S Karczmar, Milica Medved, Walter M Stadler
    Abstract:

    In dynamic contrast-enhanced MRI (DCE-MRI) studies, an accurate knowledge of the arterial contrast agent Concentration as a function of time is crucial for the estimation of kinetic parameters. In this work, a novel method for estimating the arterial input function (AIF) based on the contrast agent Concentration-vs.-time curves in two different reference tissues is described. It is assumed that the AIFs of the two tissues have the same shape, and that simple models with two or more compartments, and unknown kinetic parameters, can describe their Tracer Concentration-vs.-time curves. Based on the principle of self-consistency, one can relate the two Tracer Concentration-vs.-time curves to estimate their common underlining AIF, together with the kinetic parameters of the two tissues. In practice, the measured Concentration-vs.-time curves have noise, and the AIFs of the two tissues are not exactly the same due to different dispersion effects. These factors will produce errors in the AIF estimate. Simulation studies show that despite the two error sources, the double-reference-tissue method provides reliable estimates of the AIF. Magn Reson Med 52:1110–1117, 2004. © 2004 Wiley-Liss, Inc.