Simon Konstandin

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Conventional 2D radial projections suffer from losses in signal-to-noise ratio efficiency because of the nonuniform k-space sampling. In this study, a 2D projection reconstruction method with variable gradient amplitudes is presented to cover the k-space uniformly. The gradient is designed to keep the average sampling density constant. By this,(More)
OBJECT Sodium accumulation is involved in neuronal injury occurring in multiple sclerosis (MS). We aimed to assess sodium accumulation in progressive MS, known to suffer from severe neuronal injury. MATERIALS AND METHODS 3D-(23)Na-MRI was obtained on a 3T-MR-scanner in 20 progressive MS patients [11 primary-progressive (PPMS) and nine(More)
PURPOSE To quantify brain sodium accumulations and characterize for the first time the spatial location of sodium abnormalities at different stages of relapsing-remitting (RR) multiple sclerosis (MS) by using sodium 23 ((23)Na) magnetic resonance (MR) imaging. MATERIALS AND METHODS This study was approved by the local committee on ethics, and written(More)
Sampling density-weighted apodization projection reconstruction sequences are evaluated for three-dimensional radial imaging. The readout gradients of the sampling density-weighted apodization sequence are designed such that the locally averaged sampling density matches a Hamming filter function. This technique is compared with density-adapted projection(More)
Tissue sodium content (TSC) is a sensitive measure of pathological changes and can be detected non-invasively by MRI. For the absolute quantification of TSC, B1 inhomogeneities must be corrected, which is not well established beyond research applications. An in-depth analysis of B1 mapping methods which are suitable for application in TSC quantification is(More)
filters to 23 Na MR images. a) Original image, b) Gaussian filtered image, c) Hamming filtered image, d) Fermi filtered image, and e) T1-weighted morphological image as reference. Colors refer to intensity values of 23 Na, high signals are depicted in red. Fig. 1: 1D filter function windows at optimal parameters. Fig. 3: Plot of SNR at different window(More)
INTRODUCTION We report the first case of an intraoperative radiotherapy (IORT) in a patient with recurrent glioblastoma multiforme (GBM) who was followed up with a novel magnetic resonance imaging (MRI) method-(23)Na-MRI-in comparison to a standard contrast-enhanced (1)H-MRI and (18)F-FET-PET. METHODS A 56-year-old female patient with diagnosed GBM in(More)
A method for uniform k-space sampling of 3D ultra-short echo time (UTE) techniques with anisotropic resolution in one direction is introduced to increase signal-to-noise ratio (SNR). State-of-the-art acquisition schemes for sodium MRI with radial (projection reconstruction) and twisting (twisted projection imaging (TPI)) trajectories are investigated(More)
PURPOSE Two-dimensional projection reconstruction methods provide advantages over three-dimensional techniques because of higher flexibility regarding the resolution and shorter scan time needed. To optimize a two-dimensional radial sequence with respect to signal-to-noise ratio, variable-rate selective excitation and retrospective electrocardiogram gating(More)
Linear filters like Gaussian, Fermi or Hanning filter are used in sodium MRI post-processing to increase the signal-to-noise ratio, even though they smooth structures as well as noise and thereby cause a loss of information. To tackle that problem, we propose to use anisotropic diffusion filters (AND) instead. With 2D- and 3D-AND we have been able to(More)
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