Publications by authors named "Torsten Schlumm"

Gilles de la Tourette syndrome (GTS) is a neuropsychiatric movement disorder with reported abnormalities in various neurotransmitter systems. Considering the integral role of iron in neurotransmitter synthesis and transport, it is hypothesized that iron exhibits a role in GTS pathophysiology. As a surrogate measure of brain iron, quantitative susceptibility mapping (QSM) was performed in 28 patients with GTS and 26 matched controls.

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Gilles de la Tourette syndrome (GTS) is a neuropsychiatric movement disorder with reported abnormalities in various neurotransmitter systems. Considering the integral role of iron in neurotransmitter synthesis and transport, it is hypothesized that iron exhibits a role in GTS pathophysiology. As a surrogate measure of brain iron, quantitative susceptibility mapping (QSM) was performed in 28 patients with GTS and 26 matched controls.

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Uncovering brain-tissue microstructure including axonal characteristics is a major neuroimaging research focus. Within this scope, anisotropic properties of magnetic susceptibility in white matter have been successfully employed to estimate primary axonal trajectories using mono-tensorial models. However, anisotropic susceptibility has not yet been considered for modeling more complex fiber structures within a voxel, such as intersecting bundles, or an estimation of orientation distribution functions (ODFs).

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Article Synopsis
  • The study investigates the mechanisms behind negative BOLD responses (NBR) in the brain, particularly in the human visual cortex, contrasting them with typical positive BOLD responses (PBR).
  • Researchers employed advanced imaging techniques to improve the measurement of cerebral blood flow (CBF) and its dynamics during visual stimulation, aiming to understand how these signals relate to brain activation and deactivation.
  • Findings indicate that NBR exhibits quicker responses and different flow-metabolism coupling compared to PBR, suggesting varying neuronal contributions in activated and deactivated regions of the brain.
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Purpose: To develop a postprocessing algorithm that corrects geometric distortions due to spatial variations of the static magnetic field amplitude, B , and effects from relaxation during signal acquisition in EPI.

Theory And Methods: An analytic, complex point-spread function is deduced for k-space trajectories of EPI variants and applied to corresponding acquisitions in a resolution phantom and in human volunteers at 3 T. With the analytic point-spread function and experimental maps of B (and, optionally, the effective transverse relaxation time, ) as input, a point-spread function matrix operator is devised for distortion correction by a Thikonov-regularized deconvolution in image space.

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Article Synopsis
  • - The study introduces Multi Echo (ME) acquisitions to post-mortem diffusion MRI (dMRI), aiming to enhance image quality without drastically increasing scan time.
  • - ME-dMRI improves the Signal-to-Noise Ratio (SNR) significantly, resulting in about a 1.6x increase for white matter and a 1.9x increase for grey matter, while only adding 30% to the scanning time.
  • - The effectiveness of this new method was validated through simulations and applied to a wild chimpanzee's brain, achieving optimal SNR without introducing signal bias.
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  • - The study aims to analyze pseudo-continuous arterial spin labeling (pCASL) through simulations to optimize the measurement of cerebral blood flow using specific parameters.
  • - Simulations based on the Bloch equation assessed different factors affecting labeling efficiency, including RF field strength and gradient settings, to improve measurement reliability in a clinical setting.
  • - Findings suggest that optimal settings can achieve labeling efficiencies of about 90%, making pCASL effective regardless of magnetic field variations at 3T.
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Objective: Echo-planar imaging (EPI) with CYlindrical Center-out spatiaL Encoding (EPICYCLE) is introduced as a novel hybrid three-dimensional (3D) EPI technique. Its suitability for the tracking of a short bolus created by pseudo-continuous arterial spin labeling (pCASL) through the cerebral vasculature is demonstrated.

Materials And Methods: EPICYCLE acquires two-dimensional planes of k-space along center-out trajectories.

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In this work we present a new open source software package offering a unified framework for the real-time adaptation of fMRI stimulation procedures. The software provides a straightforward setup and highly flexible approach to adapt fMRI paradigms while the experiment is running. The general framework comprises the inclusion of parameters from subject's compliance, such as directing gaze to visually presented stimuli and physiological fluctuations, like blood pressure or pulse.

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