The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Maxim Zaitsev - One of the best experts on this subject based on the ideXlab platform.

  • Optical Tracking with two markers for robust prospective motion correction for brain imaging
    Magnetic Resonance Materials in Physics Biology and Medicine, 2015
    Co-Authors: Aditya Singh, Benjamin Zahneisen, Michael Herbst, Maxim Zaitsev, Linda Chang, Brian Keating, Thomas Ernst
    Abstract:

    ObjectiveProspective motion correction (PMC) during brain imaging using camera-based Tracking of a skin-attached marker may suffer from problems including loss of marker visibility due to the coil and false correction due to non-rigid-body facial motion, such as frowning or squinting. A modified PMC system is introduced to mitigate these problems and increase the robustness of motion correction.Materials and methodsThe method relies on simultaneously Tracking two markers, each providing six degrees of freedom, that are placed on the forehead. This allows us to track head motion when one marker is obscured and detect skin movements to prevent false corrections. Experiments were performed to compare the performance of the two-marker motion correction technique to the previous single-marker approach.ResultsExperiments validate the theory developed for adaptive marker Tracking and skin movement detection, and demonstrate improved image quality during obstruction of the line-of-sight of one marker when subjects squint or when subjects squint and move simultaneously.ConclusionThe proposed methods eliminate two common failure modes of PMC and substantially improve the robustness of PMC, and they can be applied to other Optical Tracking systems capable of Tracking multiple markers. The methods presented can be adapted to the use of more than two markers.

  • An embedded Optical Tracking system for motion-corrected magnetic resonance imaging at 7T
    Magnetic Resonance Materials in Physics Biology and Medicine, 2012
    Co-Authors: Jessica Schulz, Michael Herbst, Maxim Zaitsev, Thomas Siegert, Enrico Reimer, Christian Labadie, Julian Maclaren, Robert Turner
    Abstract:

    ObjectProspective motion correction using data from Optical Tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel Optical embedded Tracking system.Materials and methodsThe home-built Optical embedded Tracking system performs image processing within a 7T scanner bore, enabling high speed Tracking. Corrected and uncorrected in vivo MR volumes are acquired interleaved using a modified 3D FLASH sequence, and their image quality is assessed and compared.ResultsThe latency between motion and correction of the slice position was measured to be (19 ± 5) ms, and the Tracking noise has a standard deviation no greater than 10 μm/0.005° during conventional MR scanning. Prospective motion correction improved the edge strength by 16 % on average, even though the volunteers were asked to remain motionless during the acquisitions.ConclusionUsing a novel method for validating the effectiveness of in vivo prospective motion correction, we have demonstrated that prospective motion correction using motion data from the embedded Tracking system considerably improved image quality.

  • an embedded Optical Tracking system for motion corrected magnetic resonance imaging at 7t
    Magnetic Resonance Materials in Physics Biology and Medicine, 2012
    Co-Authors: Jessica Schulz, Michael Herbst, Maxim Zaitsev, Thomas Siegert, Enrico Reimer, Christian Labadie, Julian Maclaren, Robert Turner
    Abstract:

    Object Prospective motion correction using data from Optical Tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel Optical embedded Tracking system.

  • prospective motion correction for magnetic resonance spectroscopy using single camera retro grate reflector Optical Tracking
    Journal of Magnetic Resonance Imaging, 2011
    Co-Authors: Brian C Andrewsshigaki, Maxim Zaitsev, Brian S R Armstrong, Thomas Ernst
    Abstract:

    Purpose: To introduce and evaluate a method of prospective motion correction for localized proton magnetic resonance spectroscopy (1H-MRS) using a single-camera Optical Tracking system. Materials and Methods: Five healthy participants were scanned at 3T using a point-resolved spectroscopic sequence (PRESS) with a motion-Tracking module and phase navigator. Head motion in six degrees was tracked with a Retro-Grate Reflector (RGR) Tracking system and target via a mirror mounted inside the bore. Participants performed a series of three predetermined motion patterns during scanning. Results: Left–right rotation (Rz) (average 12°) resulted in an increase in the total choline to total creatine ratio (Cho/Cr) of +14.6 ± 1.5% (P = 0.0009) for scans without correction, but no change for scans with correction (+1.1 ± 1.5%; P = 0.76). Spectra with uncorrected Z-translations showed large lipid peaks (skull) with changes in Cho/Cr of −13.2 ± 1.6% (P = 0.02, no motion correction) and −2.2 ± 2.4% (P = 0.51) with correction enabled. There were no significant changes in the ratios of N-acetylaspartate, glutamate+glutamine, or myo-inositol to creatine compared to baseline scans for all experiments. Conclusion: Prospective motion correction for 1H-MRS, using single-camera RGR Tracking, can reduce spectral artifacts and quantitation errors in Cho/Cr ratios due to head motion and promises improved spectral quality and reproducibility. J. Magn. Reson. Imaging 2011. © 2011 Wiley-Liss, Inc.

Thomas Ernst - One of the best experts on this subject based on the ideXlab platform.

  • Optical Tracking with two markers for robust prospective motion correction for brain imaging
    Magnetic Resonance Materials in Physics Biology and Medicine, 2015
    Co-Authors: Aditya Singh, Benjamin Zahneisen, Michael Herbst, Maxim Zaitsev, Linda Chang, Brian Keating, Thomas Ernst
    Abstract:

    ObjectiveProspective motion correction (PMC) during brain imaging using camera-based Tracking of a skin-attached marker may suffer from problems including loss of marker visibility due to the coil and false correction due to non-rigid-body facial motion, such as frowning or squinting. A modified PMC system is introduced to mitigate these problems and increase the robustness of motion correction.Materials and methodsThe method relies on simultaneously Tracking two markers, each providing six degrees of freedom, that are placed on the forehead. This allows us to track head motion when one marker is obscured and detect skin movements to prevent false corrections. Experiments were performed to compare the performance of the two-marker motion correction technique to the previous single-marker approach.ResultsExperiments validate the theory developed for adaptive marker Tracking and skin movement detection, and demonstrate improved image quality during obstruction of the line-of-sight of one marker when subjects squint or when subjects squint and move simultaneously.ConclusionThe proposed methods eliminate two common failure modes of PMC and substantially improve the robustness of PMC, and they can be applied to other Optical Tracking systems capable of Tracking multiple markers. The methods presented can be adapted to the use of more than two markers.

  • prospective motion correction for magnetic resonance spectroscopy using single camera retro grate reflector Optical Tracking
    Journal of Magnetic Resonance Imaging, 2011
    Co-Authors: Brian C Andrewsshigaki, Maxim Zaitsev, Brian S R Armstrong, Thomas Ernst
    Abstract:

    Purpose: To introduce and evaluate a method of prospective motion correction for localized proton magnetic resonance spectroscopy (1H-MRS) using a single-camera Optical Tracking system. Materials and Methods: Five healthy participants were scanned at 3T using a point-resolved spectroscopic sequence (PRESS) with a motion-Tracking module and phase navigator. Head motion in six degrees was tracked with a Retro-Grate Reflector (RGR) Tracking system and target via a mirror mounted inside the bore. Participants performed a series of three predetermined motion patterns during scanning. Results: Left–right rotation (Rz) (average 12°) resulted in an increase in the total choline to total creatine ratio (Cho/Cr) of +14.6 ± 1.5% (P = 0.0009) for scans without correction, but no change for scans with correction (+1.1 ± 1.5%; P = 0.76). Spectra with uncorrected Z-translations showed large lipid peaks (skull) with changes in Cho/Cr of −13.2 ± 1.6% (P = 0.02, no motion correction) and −2.2 ± 2.4% (P = 0.51) with correction enabled. There were no significant changes in the ratios of N-acetylaspartate, glutamate+glutamine, or myo-inositol to creatine compared to baseline scans for all experiments. Conclusion: Prospective motion correction for 1H-MRS, using single-camera RGR Tracking, can reduce spectral artifacts and quantitation errors in Cho/Cr ratios due to head motion and promises improved spectral quality and reproducibility. J. Magn. Reson. Imaging 2011. © 2011 Wiley-Liss, Inc.

Robert Turner - One of the best experts on this subject based on the ideXlab platform.

  • An embedded Optical Tracking system for motion-corrected magnetic resonance imaging at 7T
    Magnetic Resonance Materials in Physics Biology and Medicine, 2012
    Co-Authors: Jessica Schulz, Michael Herbst, Maxim Zaitsev, Thomas Siegert, Enrico Reimer, Christian Labadie, Julian Maclaren, Robert Turner
    Abstract:

    ObjectProspective motion correction using data from Optical Tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel Optical embedded Tracking system.Materials and methodsThe home-built Optical embedded Tracking system performs image processing within a 7T scanner bore, enabling high speed Tracking. Corrected and uncorrected in vivo MR volumes are acquired interleaved using a modified 3D FLASH sequence, and their image quality is assessed and compared.ResultsThe latency between motion and correction of the slice position was measured to be (19 ± 5) ms, and the Tracking noise has a standard deviation no greater than 10 μm/0.005° during conventional MR scanning. Prospective motion correction improved the edge strength by 16 % on average, even though the volunteers were asked to remain motionless during the acquisitions.ConclusionUsing a novel method for validating the effectiveness of in vivo prospective motion correction, we have demonstrated that prospective motion correction using motion data from the embedded Tracking system considerably improved image quality.

  • an embedded Optical Tracking system for motion corrected magnetic resonance imaging at 7t
    Magnetic Resonance Materials in Physics Biology and Medicine, 2012
    Co-Authors: Jessica Schulz, Michael Herbst, Maxim Zaitsev, Thomas Siegert, Enrico Reimer, Christian Labadie, Julian Maclaren, Robert Turner
    Abstract:

    Object Prospective motion correction using data from Optical Tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel Optical embedded Tracking system.

Michael Herbst - One of the best experts on this subject based on the ideXlab platform.

  • Optical Tracking with two markers for robust prospective motion correction for brain imaging
    Magnetic Resonance Materials in Physics Biology and Medicine, 2015
    Co-Authors: Aditya Singh, Benjamin Zahneisen, Michael Herbst, Maxim Zaitsev, Linda Chang, Brian Keating, Thomas Ernst
    Abstract:

    ObjectiveProspective motion correction (PMC) during brain imaging using camera-based Tracking of a skin-attached marker may suffer from problems including loss of marker visibility due to the coil and false correction due to non-rigid-body facial motion, such as frowning or squinting. A modified PMC system is introduced to mitigate these problems and increase the robustness of motion correction.Materials and methodsThe method relies on simultaneously Tracking two markers, each providing six degrees of freedom, that are placed on the forehead. This allows us to track head motion when one marker is obscured and detect skin movements to prevent false corrections. Experiments were performed to compare the performance of the two-marker motion correction technique to the previous single-marker approach.ResultsExperiments validate the theory developed for adaptive marker Tracking and skin movement detection, and demonstrate improved image quality during obstruction of the line-of-sight of one marker when subjects squint or when subjects squint and move simultaneously.ConclusionThe proposed methods eliminate two common failure modes of PMC and substantially improve the robustness of PMC, and they can be applied to other Optical Tracking systems capable of Tracking multiple markers. The methods presented can be adapted to the use of more than two markers.

  • An embedded Optical Tracking system for motion-corrected magnetic resonance imaging at 7T
    Magnetic Resonance Materials in Physics Biology and Medicine, 2012
    Co-Authors: Jessica Schulz, Michael Herbst, Maxim Zaitsev, Thomas Siegert, Enrico Reimer, Christian Labadie, Julian Maclaren, Robert Turner
    Abstract:

    ObjectProspective motion correction using data from Optical Tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel Optical embedded Tracking system.Materials and methodsThe home-built Optical embedded Tracking system performs image processing within a 7T scanner bore, enabling high speed Tracking. Corrected and uncorrected in vivo MR volumes are acquired interleaved using a modified 3D FLASH sequence, and their image quality is assessed and compared.ResultsThe latency between motion and correction of the slice position was measured to be (19 ± 5) ms, and the Tracking noise has a standard deviation no greater than 10 μm/0.005° during conventional MR scanning. Prospective motion correction improved the edge strength by 16 % on average, even though the volunteers were asked to remain motionless during the acquisitions.ConclusionUsing a novel method for validating the effectiveness of in vivo prospective motion correction, we have demonstrated that prospective motion correction using motion data from the embedded Tracking system considerably improved image quality.

  • an embedded Optical Tracking system for motion corrected magnetic resonance imaging at 7t
    Magnetic Resonance Materials in Physics Biology and Medicine, 2012
    Co-Authors: Jessica Schulz, Michael Herbst, Maxim Zaitsev, Thomas Siegert, Enrico Reimer, Christian Labadie, Julian Maclaren, Robert Turner
    Abstract:

    Object Prospective motion correction using data from Optical Tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel Optical embedded Tracking system.

Jessica Schulz - One of the best experts on this subject based on the ideXlab platform.

  • An embedded Optical Tracking system for motion-corrected magnetic resonance imaging at 7T
    Magnetic Resonance Materials in Physics Biology and Medicine, 2012
    Co-Authors: Jessica Schulz, Michael Herbst, Maxim Zaitsev, Thomas Siegert, Enrico Reimer, Christian Labadie, Julian Maclaren, Robert Turner
    Abstract:

    ObjectProspective motion correction using data from Optical Tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel Optical embedded Tracking system.Materials and methodsThe home-built Optical embedded Tracking system performs image processing within a 7T scanner bore, enabling high speed Tracking. Corrected and uncorrected in vivo MR volumes are acquired interleaved using a modified 3D FLASH sequence, and their image quality is assessed and compared.ResultsThe latency between motion and correction of the slice position was measured to be (19 ± 5) ms, and the Tracking noise has a standard deviation no greater than 10 μm/0.005° during conventional MR scanning. Prospective motion correction improved the edge strength by 16 % on average, even though the volunteers were asked to remain motionless during the acquisitions.ConclusionUsing a novel method for validating the effectiveness of in vivo prospective motion correction, we have demonstrated that prospective motion correction using motion data from the embedded Tracking system considerably improved image quality.

  • an embedded Optical Tracking system for motion corrected magnetic resonance imaging at 7t
    Magnetic Resonance Materials in Physics Biology and Medicine, 2012
    Co-Authors: Jessica Schulz, Michael Herbst, Maxim Zaitsev, Thomas Siegert, Enrico Reimer, Christian Labadie, Julian Maclaren, Robert Turner
    Abstract:

    Object Prospective motion correction using data from Optical Tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel Optical embedded Tracking system.